Which Foods Best Boost Your Immune System?
By Judy Muller
Nnutrition experts say much of what our bodies need to fight off infection can be found in foods.
In its latest edition, Prevention magazine says a poor diet is a top factor in making us susceptible to illness. It then lists the top five foods that give your body the best immunity: beef, sweet potatoes, mushrooms, tea and yogurt. While an all-around healthy diet is crucial, these particular foods help us best flex our immunity muscles, the magazine said.
Each of the foods should be eaten every day to boost immunity, nutritionist Heidi Skolnik told Good Morning America .
"We should eat these daily, as often as we can, especially in this weather," she said. Plenty of rest is also essential to keeping our immune systems up, she said. Health experts also advise a flu shot.
Beef It Up a Little
Of the five immunity-boosting foods, beef may be the most surprising, considering health experts recommend limiting our red meat intake. But moderation is still key.
"People should still not be eating a 24-ounce porterhouse on a daily basis," Skolnik said. "A three-ounce portion of beef -- and importantly very lean beef that is low in fat -- is an important source of zinc."
Zinc deficiency can greatly increase your risk of infection. Zinc helps develop white blood cells, the cells that we really need those to fight off foreign bacteria and viruses.
Vegetarians and those who do not eat red meat can look for their zinc supply in poultry, pork, fortified cereals, yogurt and milk. If you like oysters, they are also a fantastic source of zinc, Skolnik adds.
We should also be eating orange vegetables daily, especially this time of year. Sweet potatoes, or any of the orange vegetables, are a great way to add vitamin A to our diets. The reason? Vitamin A is important for our skin, which is the first line of defense for our immune systems, Skolnik said.
"Think orange, foods like sweet potatoes, and also carrots, squash, pumpkin," Skolnik said. "These are all great, especially because they are all in season this time of year. They all are great sources of beta-carotene, which the body quickly turns into vitamin A."
Although many of us eat carrots, it is often two or three days between servings, so we need to eat them more regularly, Skolnik said.
Mushrooms, Yogurt to the Rescue
To add to those 3-ounce lean burgers, mushrooms are another high-immunity food.
"Like beef, mushrooms help in the production of white blood cells in the body," Skolnik said. "Some recent studies have also found that they may make white blood cells act more aggressively against foreign bacteria."
The very best kinds of mushrooms are shiitake and maitake, which are available in most supermarkets.
In addition, the English may know something about fighting off a cold. Skolnik recommends a cup of black or green tea a day to muscle up our immune systems.
"Tea is a great source of polyphenols," Skolnik said. "Polyphenols clean up free radicals, damaging compounds that can hurt your DNA and accelerate aging."
Antioxidants take care of the free radicals, and tea has more antioxidants per part than fruits and vegetables.
Yogurt, another immunity-boosting food, is especially important to eat, particularly after you have been prescribed antibiotics. Brands that contain active cultures are a good source of healthy bacteria for your stomach.
"When we take antibiotics they destroy most of the bacteria in our body," Skolnik said. "The problem is that there are some beneficial bacteria that the antibiotics take care of as well. We need these, especially those found in our intestines, to help us break down foods."
The lack of those bacteria can make us vulnerable to germs that cause diarrhea, for instance.
(We recommend taking a product called Colon Essentials to rebuild the friendly bacteria in you stomach and intestines. We also have a product called Digestive Balance which will help you digest and breakdown the food you eat.)
Thursday, December 13, 2007
The Truth about Your Immune System: What you need to know
The Truth about Your Immune System: What you need to know
Description
Table of Contents
An excerpt from this report
Printed Version: $16.00 Electronic Download (PDF): $16.00 Print + Electronic Download (PDF): $24.00
Boost your Immune System
Can you boost immunity? Will certain vitamins or herbs help you fend off infection and disease? What about diet and exercise? Your immune system is your most powerful protector but it’s not fool proof. The Truth about Your Immune System sets the record straight about how your immune system fights off germs and how you can help your immune system operate at its best. Includes practical steps you can take to improve your chances of staying healthy and to fight off infection from viruses, bacteria, fungus and other disease-causing microbes. Prepared in collaboration with the editors at Harvard Medical School and Michael L. Starnbach, professor of Microbiology and Molecular Genetics, Harvard Medical School. 38 pages. (updated: 2007)
Back to top >
Table of Contents:
How your immune system works
When? Where? Why?
Microbes and hosts: Living together
The immune system in three acts
Act One: Defending the barricades
Act Two: The innate immune system
Act Three: The adaptive immune system
What about vaccines?
How vaccines work
Types of vaccines
Vaccinating infants and children
Do vaccines pose health risks?
New vaccine players
When things go wrong
Immunodeficiency disease
Hypersensitivity disorders (allergies)
Autoimmune disease
Cancer: Missed cues
What can you do?
Adopt healthy living strategies
Be skeptical
Age and immunity
What about diet?
Herbs and other supplements
The stress connection
Does being cold make you sick?
Exercise: Good or bad for immunity?
Looking ahead
“New and improved” innate immune system
Cell communication
Tomorrow’s vaccines
Glossary
Resources
Government organizations
Publications
Printed Version: $16.00 Electronic Download (PDF): $16.00 Print + Electronic Download (PDF): $24.00
Back to top >
Here's an Excerpt from this Immune Special Health Report
You can’t feel it or see it. You can’t take its pulse or its temperature. But out of sight and out of mind, your immune system is quietly and constantly patrolling your body to detect and destroy infectious microbes. It is your most powerful protector, working tirelessly around the clock to keep you safe.
Despite its low-key profile, the immune system is the subject of great attention both in the laboratories of prominent scientists and on the shelves of retail stores carrying countless products that purport to boost or support immunity. While researchers are still trying to understand how the immune system works, product manufacturers have rushed to market everything from herbal teas to vitamin supplements that they claim will improve your immune response, with little evidence to support those claims.
To be sure, your immune system is a precious asset. It protects you from the ceaseless assaults of bacteria, viruses, fungi, and parasites. The danger is very real. In 2004, 61,472 people in the United States died of influenza or pneumonia, making those diseases together the eighth leading cause of death. And each year, around 215,000 people in the United States die from a severe bacterial infection known as sepsis, which is more than the number who die from breast, colorectal, pancreatic, and prostate cancers combined. Worldwide, measles killed about 450,000 people in 2004, most of them children. Tuberculosis, once considered under control, was responsible for 1.7 million deaths the same year. At the same time, infectious diseases are emerging around the globe in such forms as bird flu and severe acute respiratory syndrome (SARS). Although the confirmed number of deaths from bird flu is small, experts fear a bird flu pandemic could take a vast toll on human life.
In response to such threats and many that have come before, the human body has developed a coordinated immune response that is both a marvel of elegant simplicity and an amazingly complex set of biochemical interactions. And the harnessing of this process with vaccinations is arguably the greatest public health accomplishment since the beginning of the 20th century. As a result, many infectious diseases are in retreat. Moreover, vaccination has lead to the eradication of smallpox and the near eradication of a number of other diseases, such as polio.
Usually, your immune system is quite effective in warding off disease. But sometimes things go wrong. A bacterium, virus, or other pathogen might make it past your immune defenses and make you sick. In addition, more than 1 in every 500 U.S. citizens is born with an immune system defect. Even allergies are an example of an immune response gone awry.
Learning how the immune system functions and why things sometimes go wrong is key to today’s medical efforts to prevent and cure disease. Even as scientists work on these problems, you can do your part to protect yourself from disease. This report takes you on a tour through your immune system and includes practical steps you can take to assist your immune system in its mission.
Description
Table of Contents
An excerpt from this report
Printed Version: $16.00 Electronic Download (PDF): $16.00 Print + Electronic Download (PDF): $24.00
Boost your Immune System
Can you boost immunity? Will certain vitamins or herbs help you fend off infection and disease? What about diet and exercise? Your immune system is your most powerful protector but it’s not fool proof. The Truth about Your Immune System sets the record straight about how your immune system fights off germs and how you can help your immune system operate at its best. Includes practical steps you can take to improve your chances of staying healthy and to fight off infection from viruses, bacteria, fungus and other disease-causing microbes. Prepared in collaboration with the editors at Harvard Medical School and Michael L. Starnbach, professor of Microbiology and Molecular Genetics, Harvard Medical School. 38 pages. (updated: 2007)
Back to top >
Table of Contents:
How your immune system works
When? Where? Why?
Microbes and hosts: Living together
The immune system in three acts
Act One: Defending the barricades
Act Two: The innate immune system
Act Three: The adaptive immune system
What about vaccines?
How vaccines work
Types of vaccines
Vaccinating infants and children
Do vaccines pose health risks?
New vaccine players
When things go wrong
Immunodeficiency disease
Hypersensitivity disorders (allergies)
Autoimmune disease
Cancer: Missed cues
What can you do?
Adopt healthy living strategies
Be skeptical
Age and immunity
What about diet?
Herbs and other supplements
The stress connection
Does being cold make you sick?
Exercise: Good or bad for immunity?
Looking ahead
“New and improved” innate immune system
Cell communication
Tomorrow’s vaccines
Glossary
Resources
Government organizations
Publications
Printed Version: $16.00 Electronic Download (PDF): $16.00 Print + Electronic Download (PDF): $24.00
Back to top >
Here's an Excerpt from this Immune Special Health Report
You can’t feel it or see it. You can’t take its pulse or its temperature. But out of sight and out of mind, your immune system is quietly and constantly patrolling your body to detect and destroy infectious microbes. It is your most powerful protector, working tirelessly around the clock to keep you safe.
Despite its low-key profile, the immune system is the subject of great attention both in the laboratories of prominent scientists and on the shelves of retail stores carrying countless products that purport to boost or support immunity. While researchers are still trying to understand how the immune system works, product manufacturers have rushed to market everything from herbal teas to vitamin supplements that they claim will improve your immune response, with little evidence to support those claims.
To be sure, your immune system is a precious asset. It protects you from the ceaseless assaults of bacteria, viruses, fungi, and parasites. The danger is very real. In 2004, 61,472 people in the United States died of influenza or pneumonia, making those diseases together the eighth leading cause of death. And each year, around 215,000 people in the United States die from a severe bacterial infection known as sepsis, which is more than the number who die from breast, colorectal, pancreatic, and prostate cancers combined. Worldwide, measles killed about 450,000 people in 2004, most of them children. Tuberculosis, once considered under control, was responsible for 1.7 million deaths the same year. At the same time, infectious diseases are emerging around the globe in such forms as bird flu and severe acute respiratory syndrome (SARS). Although the confirmed number of deaths from bird flu is small, experts fear a bird flu pandemic could take a vast toll on human life.
In response to such threats and many that have come before, the human body has developed a coordinated immune response that is both a marvel of elegant simplicity and an amazingly complex set of biochemical interactions. And the harnessing of this process with vaccinations is arguably the greatest public health accomplishment since the beginning of the 20th century. As a result, many infectious diseases are in retreat. Moreover, vaccination has lead to the eradication of smallpox and the near eradication of a number of other diseases, such as polio.
Usually, your immune system is quite effective in warding off disease. But sometimes things go wrong. A bacterium, virus, or other pathogen might make it past your immune defenses and make you sick. In addition, more than 1 in every 500 U.S. citizens is born with an immune system defect. Even allergies are an example of an immune response gone awry.
Learning how the immune system functions and why things sometimes go wrong is key to today’s medical efforts to prevent and cure disease. Even as scientists work on these problems, you can do your part to protect yourself from disease. This report takes you on a tour through your immune system and includes practical steps you can take to assist your immune system in its mission.
How Your Immune System Works
How Your Immune System Works
by Marshall Brain
Inside This Article
1.
Introduction to How Your Immune System Works
2.
Seeing Your Immune System
3.
Basics of the Immune System
4.
Viral or Bacterial Infection
5.
Components of the Immune System
6.
Lymph System
7.
Thymus
8.
Antibodies
9.
Complement System
10.
White Blood Cells
11.
Leukocytes
12.
Different Roles
13.
T Cells
14.
Vaccinations
15.
AIDS
16.
How Antibiotics Work
17.
Immune System Mistakes
18.
Lots More Information
19.
See all The Body articles
Photo courtesy -->Inside your body there is an amazing protection mechanism called the immune system. It is designed to defend you against millions of bacteria, microbes, viruses, toxins and parasites that would love to invade your body. To understand the power of the immune system, all that you have to do is look at what happens to anything once it dies. That sounds gross, but it does show you something very important about your immune system.
When something dies, its immune system (along with everything else) shuts down. In a matter of hours, the body is invaded by all sorts of bacteria, microbes, parasites... None of these things are able to get in when your immune system is working, but the moment your immune system stops the door is wide open. Once you die it only takes a few weeks for these organisms to completely dismantle your body and carry it away, until all that's left is a skeleton. Obviously your immune system is doing something amazing to keep all of that dismantling from happening when you are alive.
The immune system is complex, intricate and interesting. And there are at least two good reasons for you to know more about it. First, it is just plain fascinating to understand where things like fevers, hives, inflammation, etc., come from when they happen inside your own body. You also hear a lot about the immune system in the news as new parts of it are understood and new drugs come on the market -- knowing about the immune system makes these news stories understandable. In this article, we will take a look at how your immune system works so that you can understand what it is doing for you each day, as well as what it is not.
NEXT
Inside This Article
1.
Introduction to How Your Immune System Works
2.
Seeing Your Immune System
3.
Basics of the Immune System
4.
Viral or Bacterial Infection
5.
Components of the Immune System
6.
Lymph System
7.
Thymus
8.
Antibodies
9.
Complement System
10.
White Blood Cells
by Marshall Brain
Inside This Article
1.
Introduction to How Your Immune System Works
2.
Seeing Your Immune System
3.
Basics of the Immune System
4.
Viral or Bacterial Infection
5.
Components of the Immune System
6.
Lymph System
7.
Thymus
8.
Antibodies
9.
Complement System
10.
White Blood Cells
11.
Leukocytes
12.
Different Roles
13.
T Cells
14.
Vaccinations
15.
AIDS
16.
How Antibiotics Work
17.
Immune System Mistakes
18.
Lots More Information
19.
See all The Body articles
Photo courtesy -->Inside your body there is an amazing protection mechanism called the immune system. It is designed to defend you against millions of bacteria, microbes, viruses, toxins and parasites that would love to invade your body. To understand the power of the immune system, all that you have to do is look at what happens to anything once it dies. That sounds gross, but it does show you something very important about your immune system.
When something dies, its immune system (along with everything else) shuts down. In a matter of hours, the body is invaded by all sorts of bacteria, microbes, parasites... None of these things are able to get in when your immune system is working, but the moment your immune system stops the door is wide open. Once you die it only takes a few weeks for these organisms to completely dismantle your body and carry it away, until all that's left is a skeleton. Obviously your immune system is doing something amazing to keep all of that dismantling from happening when you are alive.
The immune system is complex, intricate and interesting. And there are at least two good reasons for you to know more about it. First, it is just plain fascinating to understand where things like fevers, hives, inflammation, etc., come from when they happen inside your own body. You also hear a lot about the immune system in the news as new parts of it are understood and new drugs come on the market -- knowing about the immune system makes these news stories understandable. In this article, we will take a look at how your immune system works so that you can understand what it is doing for you each day, as well as what it is not.
NEXT
Inside This Article
1.
Introduction to How Your Immune System Works
2.
Seeing Your Immune System
3.
Basics of the Immune System
4.
Viral or Bacterial Infection
5.
Components of the Immune System
6.
Lymph System
7.
Thymus
8.
Antibodies
9.
Complement System
10.
White Blood Cells
The immune system
The Body's First Line of Defense
How the Immune System Works
Antibodies
T Cells
Immune System Process The Body's First Line of DefenseThe immune system is a complex of organs--highly specialized cells and even a circulatory system separate from blood vessels--all of which work together to clear infection from the body.
The organs of the immune system, positioned throughout the body, are called lymphoid organs. The word "lymph" in Greek means a pure, clear stream--an appropriate description considering its appearance and purpose.
Lymphatic vessels form a circulatory system that operates in close partnership with blood circulation.
Lymphatic vessels and lymph nodes are the parts of the special circulatory system that carries lymph, a transparent fluid containing white blood cells, chiefly lymphocytes.
Lymph bathes the tissues of the body, and the lymphatic vessels collect and move it eventually back into the blood circulation. Lymph nodes dot the network of lymphatic vessels and provide meeting grounds for the immune system cells that defend against invaders. The spleen, at the upper left of the abdomen, is also a staging ground and a place where immune system cells confront foreign microbes.
Organs and tissues of the immune system dot the body in a protective network of barriers to infection.
Pockets of lymphoid tissue are in many other locations throughout the body, such as the bone marrow and thymus. Tonsils, adenoids, Peyer's patches, and the appendix are also lymphoid tissues.
Both immune cells and foreign molecules enter the lymph nodes via blood vessels or lymphatic vessels. All immune cells exit the lymphatic system and eventually return to the bloodstream. Once in the bloodstream, lymphocytes are transported to tissues throughout the body, where they act as sentries on the lookout for foreign antigens.
How the Immune System WorksCells that will grow into the many types of more specialized cells that circulate throughout the immune system are produced in the bone marrow. This nutrient-rich, spongy tissue is found in the center shafts of certain long, flat bones of the body, such as the bones of the pelvis. The cells most relevant for understanding vaccines are the lymphocytes, numbering close to one trillion.
The two major classes of lymphocytes are B cells, which grow to maturity in the bone marrow, and T cells, which mature in the thymus, high in the chest behind the breastbone.
B cells produce antibodies that circulate in the blood and lymph streams and attach to foreign antigens to mark them for destruction by other immune cells.
B cells are part of what is known as antibody-mediated or humoral immunity, so called because the antibodies circulate in blood and lymph, which the ancient Greeks called, the body's "humors."
B cells become plasma cells, which produce antibodies when a foreign antigen triggers the immune response.
Certain T cells, which also patrol the blood and lymph for foreign invaders, can do more than mark the antigens; they attack and destroy diseased cells they recognize as foreign. T lymphocytes are responsible for cell-mediated immunity (or cellular immunity). T cells also orchestrate, regulate and coordinate the overall immune response. T cells depend on unique cell surface molecules called the major histocompatibility complex (MHC) to help them recognize antigen fragments.
Antibodies produced by cells of the immune system recognize foreign antigens and mark them for destruction.
Antibodies
The antibodies that B cells produce are basic templates with a special region that is highly specific to target a given antigen. Much like a car coming off a production line, the antibody's frame remains constant, but through chemical and cellular messages, the immune system selects a green sedan, a red convertible or a white truck to combat this particular invader.
However, in contrast to cars, the variety of antibodies is very large. Different antibodies are destined for different purposes. Some coat the foreign invaders to make them attractive to the circulating scavenger cells, phagocytes, that will engulf an unwelcome microbe.
When some antibodies combine with antigens, they activate a cascade of nine proteins, known as complement, that have been circulating in inactive form in the blood. Complement forms a partnership with antibodies, once they have reacted with antigen, to help destroy foreign invaders and remove them from the body. Still other types of antibodies block viruses from entering cells.
T CellsT cells have two major roles in immune defense. Regulatory T cells are essential for orchestrating the response of an elaborate system of different types of immune cells.
Helper T cells, for example, also known as CD4 positive T cells (CD4+ T cells), alert B cells to start making antibodies; they also can activate other T cells and immune system scavenger cells called macrophages and influence which type of antibody is produced.
Certain T cells, called CD8 positive T cells (CD8+ T cells), can become killer cells that attack and destroy infected cells. The killer T cells are also called cytotoxic T cells or CTLs (cytotoxic lymphocytes).
T lymphocytes become CD4+ or helper T cells, or they can become CD8+ cells, which in turn can become killer T cells, also called cytotoxic T cells.
Immune system processActivation of helper T cells
After it engulfs and processes an antigen, the macrophage displays the antigen fragments combined with a Class II MHC protein on the macrophage cell surface. The antigen-protein combination attracts a helper T cell, and promotes its activation.
Activation of cytotoxic T cells
After a macrophage engulfs and processes an antigen, the macrophage displays the antigen fragments combined with a Class I MHC protein on the macrophage cell surface. A receptor on a circulating, resting cytotoxic T cell recognizes the antigen-protein complex and binds to it. The binding process and a helper T cell activate the cytotoxic T cell so that it can attack and destroy the diseased cell.
Activation of B cells to make antibody
A B cell uses one of its receptors to bind to its matching antigen, which the B cell engulfs and processes. The B cell then displays a piece of the antigen, bound to a Class II MHC protein, on the cell surface. This whole complex then binds to an activated helper T cell. This binding process stimulates the transformation of the B cell into an antibody-secreting plasma cell.
How the Immune System Works
Antibodies
T Cells
Immune System Process The Body's First Line of DefenseThe immune system is a complex of organs--highly specialized cells and even a circulatory system separate from blood vessels--all of which work together to clear infection from the body.
The organs of the immune system, positioned throughout the body, are called lymphoid organs. The word "lymph" in Greek means a pure, clear stream--an appropriate description considering its appearance and purpose.
Lymphatic vessels form a circulatory system that operates in close partnership with blood circulation.
Lymphatic vessels and lymph nodes are the parts of the special circulatory system that carries lymph, a transparent fluid containing white blood cells, chiefly lymphocytes.
Lymph bathes the tissues of the body, and the lymphatic vessels collect and move it eventually back into the blood circulation. Lymph nodes dot the network of lymphatic vessels and provide meeting grounds for the immune system cells that defend against invaders. The spleen, at the upper left of the abdomen, is also a staging ground and a place where immune system cells confront foreign microbes.
Organs and tissues of the immune system dot the body in a protective network of barriers to infection.
Pockets of lymphoid tissue are in many other locations throughout the body, such as the bone marrow and thymus. Tonsils, adenoids, Peyer's patches, and the appendix are also lymphoid tissues.
Both immune cells and foreign molecules enter the lymph nodes via blood vessels or lymphatic vessels. All immune cells exit the lymphatic system and eventually return to the bloodstream. Once in the bloodstream, lymphocytes are transported to tissues throughout the body, where they act as sentries on the lookout for foreign antigens.
How the Immune System WorksCells that will grow into the many types of more specialized cells that circulate throughout the immune system are produced in the bone marrow. This nutrient-rich, spongy tissue is found in the center shafts of certain long, flat bones of the body, such as the bones of the pelvis. The cells most relevant for understanding vaccines are the lymphocytes, numbering close to one trillion.
The two major classes of lymphocytes are B cells, which grow to maturity in the bone marrow, and T cells, which mature in the thymus, high in the chest behind the breastbone.
B cells produce antibodies that circulate in the blood and lymph streams and attach to foreign antigens to mark them for destruction by other immune cells.
B cells are part of what is known as antibody-mediated or humoral immunity, so called because the antibodies circulate in blood and lymph, which the ancient Greeks called, the body's "humors."
B cells become plasma cells, which produce antibodies when a foreign antigen triggers the immune response.
Certain T cells, which also patrol the blood and lymph for foreign invaders, can do more than mark the antigens; they attack and destroy diseased cells they recognize as foreign. T lymphocytes are responsible for cell-mediated immunity (or cellular immunity). T cells also orchestrate, regulate and coordinate the overall immune response. T cells depend on unique cell surface molecules called the major histocompatibility complex (MHC) to help them recognize antigen fragments.
Antibodies produced by cells of the immune system recognize foreign antigens and mark them for destruction.
Antibodies
The antibodies that B cells produce are basic templates with a special region that is highly specific to target a given antigen. Much like a car coming off a production line, the antibody's frame remains constant, but through chemical and cellular messages, the immune system selects a green sedan, a red convertible or a white truck to combat this particular invader.
However, in contrast to cars, the variety of antibodies is very large. Different antibodies are destined for different purposes. Some coat the foreign invaders to make them attractive to the circulating scavenger cells, phagocytes, that will engulf an unwelcome microbe.
When some antibodies combine with antigens, they activate a cascade of nine proteins, known as complement, that have been circulating in inactive form in the blood. Complement forms a partnership with antibodies, once they have reacted with antigen, to help destroy foreign invaders and remove them from the body. Still other types of antibodies block viruses from entering cells.
T CellsT cells have two major roles in immune defense. Regulatory T cells are essential for orchestrating the response of an elaborate system of different types of immune cells.
Helper T cells, for example, also known as CD4 positive T cells (CD4+ T cells), alert B cells to start making antibodies; they also can activate other T cells and immune system scavenger cells called macrophages and influence which type of antibody is produced.
Certain T cells, called CD8 positive T cells (CD8+ T cells), can become killer cells that attack and destroy infected cells. The killer T cells are also called cytotoxic T cells or CTLs (cytotoxic lymphocytes).
T lymphocytes become CD4+ or helper T cells, or they can become CD8+ cells, which in turn can become killer T cells, also called cytotoxic T cells.
Immune system processActivation of helper T cells
After it engulfs and processes an antigen, the macrophage displays the antigen fragments combined with a Class II MHC protein on the macrophage cell surface. The antigen-protein combination attracts a helper T cell, and promotes its activation.
Activation of cytotoxic T cells
After a macrophage engulfs and processes an antigen, the macrophage displays the antigen fragments combined with a Class I MHC protein on the macrophage cell surface. A receptor on a circulating, resting cytotoxic T cell recognizes the antigen-protein complex and binds to it. The binding process and a helper T cell activate the cytotoxic T cell so that it can attack and destroy the diseased cell.
Activation of B cells to make antibody
A B cell uses one of its receptors to bind to its matching antigen, which the B cell engulfs and processes. The B cell then displays a piece of the antigen, bound to a Class II MHC protein, on the cell surface. This whole complex then binds to an activated helper T cell. This binding process stimulates the transformation of the B cell into an antibody-secreting plasma cell.
Additional Resources
Additional ResourcesPlease Note: By clicking a link to any resource listed on this page, you will be leaving the KidsHealth site.
Immune Deficiency Foundation (IDF)http://www.primaryimmune.orgIDF's mission is to improve the diagnosis and treatment of patients with primary immunodeficiency diseases through research and education.American Academy of Allergy, Asthma, and Immunologyhttp://www.aaaai.org/The American Academy of Allergy, Asthma, and Immunology offers up-to-date information and a find-an-allergist search tool.Chronic Fatigue and Immune Dysfunction Syndrome Association of America (CFIDS)http://www.cfids.orgThe CFIDS Association of America is a charitable organization dedicated to conquering chronic fatigue and immune dysfunction syndrome (CFIDS), also known as chronic fatigue syndrome (CFS). Contact CFIDS at: Chronic Fatigue and Immune Dysfunction Syndrome Association of America P.O. Box 220398 Charlotte, NC 28222-0398 (704) 365-2343Arthritis Foundationhttp://www.arthritis.orgThe mission of this group is to support research to find the cure for and prevention of arthritis and to improve the quality of life for those affected by arthritis.Lupus Foundation of Americahttp://www.lupus.orgThe mission of the Lupus Foundation of America is to educate and support those affected by lupus and find a cure. Call: (800) 558-0121 (for written information) or (310) 670-9292 (for all other questions)American Academy of Pediatrics (AAP)http://www.aap.orgThe AAP is committed to the health and well-being of infants, adolescents, and young adults. The website offers news articles and tips on health for families.National Institutes of Health (NIH)http://www.nih.govNIH is an Agency under the U.S. Department of Health and Human Services, and offers health information and scientific resources.Leukemia & Lymphoma Societyhttp://www.leukemia-lymphoma.orgThe Leukemia & Lymphoma Society is dedicated to funding blood-cancer research, education, and patient services. The Society's mission is to cure leukemia, lymphoma, Hodgkin's disease, and myeloma, and to improve the quality of life of patients and their families. Call: (914) 949-5213The Food Allergy and Anaphylaxis Network (FAAN)http://www.foodallergy.orgThe FAAN mession is to raise public awareness, provide advocacy and education and to advance research on behavior for all of those affected by food allergies and anaphylaxis.American Foundation for AIDS Research (amfAR)http://www.amfar.org/cgi-bin/iowa/index.htmlThis nonprofit organization is dedicated to the support of AIDS research, prevention, treatment education, and advocacy.
Immune Deficiency Foundation (IDF)http://www.primaryimmune.orgIDF's mission is to improve the diagnosis and treatment of patients with primary immunodeficiency diseases through research and education.American Academy of Allergy, Asthma, and Immunologyhttp://www.aaaai.org/The American Academy of Allergy, Asthma, and Immunology offers up-to-date information and a find-an-allergist search tool.Chronic Fatigue and Immune Dysfunction Syndrome Association of America (CFIDS)http://www.cfids.orgThe CFIDS Association of America is a charitable organization dedicated to conquering chronic fatigue and immune dysfunction syndrome (CFIDS), also known as chronic fatigue syndrome (CFS). Contact CFIDS at: Chronic Fatigue and Immune Dysfunction Syndrome Association of America P.O. Box 220398 Charlotte, NC 28222-0398 (704) 365-2343Arthritis Foundationhttp://www.arthritis.orgThe mission of this group is to support research to find the cure for and prevention of arthritis and to improve the quality of life for those affected by arthritis.Lupus Foundation of Americahttp://www.lupus.orgThe mission of the Lupus Foundation of America is to educate and support those affected by lupus and find a cure. Call: (800) 558-0121 (for written information) or (310) 670-9292 (for all other questions)American Academy of Pediatrics (AAP)http://www.aap.orgThe AAP is committed to the health and well-being of infants, adolescents, and young adults. The website offers news articles and tips on health for families.National Institutes of Health (NIH)http://www.nih.govNIH is an Agency under the U.S. Department of Health and Human Services, and offers health information and scientific resources.Leukemia & Lymphoma Societyhttp://www.leukemia-lymphoma.orgThe Leukemia & Lymphoma Society is dedicated to funding blood-cancer research, education, and patient services. The Society's mission is to cure leukemia, lymphoma, Hodgkin's disease, and myeloma, and to improve the quality of life of patients and their families. Call: (914) 949-5213The Food Allergy and Anaphylaxis Network (FAAN)http://www.foodallergy.orgThe FAAN mession is to raise public awareness, provide advocacy and education and to advance research on behavior for all of those affected by food allergies and anaphylaxis.American Foundation for AIDS Research (amfAR)http://www.amfar.org/cgi-bin/iowa/index.htmlThis nonprofit organization is dedicated to the support of AIDS research, prevention, treatment education, and advocacy.
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Spleen and Lymphatic SystemThe lymphatic system is an extensive drainage system that returns water and proteins from various tissues back to the bloodstream.
immune system
The immune system, which is made up of special cells, proteins, tissues, and organs, defends people against germs and microorganisms every day. In most cases, the immune system does a great job of keeping people healthy and preventing infections. But sometimes problems with the immune system can lead to illness and infection.
What the Immune System Does
The immune system is the body's defense against infectious organisms and other invaders. Through a series of steps called the immune response, the immune system attacks organisms and substances that invade our systems and cause disease. The immune system is made up of a network of cells, tissues, and organs that work together to protect the body.
The cells that are part of this defense system are white blood cells, or leukocytes. They come in two basic types (more on these below), which combine to seek out and destroy the organisms or substances that cause disease.
Leukocytes are produced or stored in many locations throughout the body, including the thymus, spleen, and bone marrow. For this reason, they are called the lymphoid organs. There are also clumps of lymphoid tissue throughout the body, primarily in the form of lymph nodes, that house the leukocytes.
The leukocytes circulate through the body between the organs and nodes by means of the lymphatic vessels. Leukocytes can also circulate through the blood vessels. In this way, the immune system works in a coordinated manner to monitor the body for germs or substances that might cause problems.
The two basic types of leukocytes are:
phagocytes, cells that chew up invading organisms
lymphocytes, cells that allow the body to remember and recognize previous invaders and help the body destroy them
A number of different cells are considered phagocytes. The most common type is the neutrophil, which primarily fights bacteria. If doctors are worried about a bacterial infection, they might order a blood test to see if a patient has an increased number of neutrophils triggered by the infection. Other types of phagocytes have their own jobs to make sure that the body responds appropriately to a specific type of invader.
There are two kinds of lymphocytes: the B lymphocytes and the T lymphocytes. Lymphocytes start out in the bone marrow and either stay there and mature into B cells, or they leave for the thymus gland, where they mature into T cells. B lymphocytes and T lymphocytes have separate jobs to do: B lymphocytes are like the body's military intelligence system, seeking out their targets and sending defenses to lock onto them. T cells are like the soldiers, destroying the invaders that the intelligence system has identified. Here's how it works.
Antigens are foreign substances that invade the body. When an antigen is detected, several types of cells work together to recognize and respond to it. These cells trigger the B lymphocytes to produce antibodies, specialized proteins that lock onto specific antigens. Antibodies and antigens fit together like a key and a lock.
Once the B lymphocytes have produced antibodies, these antibodies continue to exist in a person's body, so that if the same antigen is presented to the immune system again, the antibodies are already there to do their job. That's why if someone gets sick with a certain disease, like chickenpox, that person typically doesn't get sick from it again. This is also why we use immunizations to prevent getting certain diseases. The immunization introduces the body to the antigen in a way that doesn't make a person sick, but it does allow the body to produce antibodies that will then protect that person from future attack by the germ or substance that produces that particular disease.
Although antibodies can recognize an antigen and lock onto it, they are not capable of destroying it without help. That is the job of the T cells. The T cells are part of the system that destroys antigens that have been tagged by antibodies or cells that have been infected or somehow changed. (There are actually T cells that are called "killer cells.") T cells are also involved in helping signal other cells (like phagocytes) to do their jobs.
Antibodies can also neutralize toxins (poisonous or damaging substances) produced by different organisms. Lastly, antibodies can activate a group of proteins called complement that are also part of the immune system. Complement assists in killing bacteria, viruses, or infected cells.
All of these specialized cells and parts of the immune system offer the body protection against disease. This protection is called immunity.
Humans have three types of immunity — innate, adaptive, and passive:
Innate Immunity
Everyone is born with innate (or natural) immunity, a type of general protection that humans have. Many of the germs that affect other species don't harm us. For example, the viruses that cause leukemia in cats or distemper in dogs don't affect humans. Innate immunity works both ways because some viruses that make humans ill — such as the virus that causes HIV/AIDS — don't make cats or dogs sick either.
Innate immunity also includes the external barriers of the body, like the skin and mucous membranes (like those that line the nose, throat, and gastrointestinal tract), which are our first line of defense in preventing diseases from entering the body. If this outer defensive wall is broken (like if you get a cut), the skin attempts to heal the break quickly and special immune cells on the skin attack invading germs.
Adaptive Immunity
We also have a second kind of protection called adaptive (or active) immunity. This type of immunity develops throughout our lives. Adaptive immunity involves the lymphocytes (as in the process described above) and develops as children and adults are exposed to diseases or immunized against diseases through vaccination.
Passive Immunity
Passive immunity is "borrowed" from another source and it lasts for a short time. For example, antibodies in a mother's breast milk provide an infant with temporary immunity to diseases that the mother has been exposed to. This can help protect the infant against infection during the early years of childhood.
Everyone's immune system is different. Some people never seem to get infections, whereas others seem to be sick all the time. As people get older, they usually become immune to more germs as the immune system comes into contact with more and more of them. That's why adults and teens tend to get fewer colds than kids — their bodies have learned to recognize and immediately attack many of the viruses that cause colds.
Things That Can Go Wrong With the Immune System
Disorders of the immune system can be broken down into four main categories:
immunodeficiency disorders (primary or acquired)
autoimmune disorders (in which the body's own immune system attacks its own tissue as foreign matter)
allergic disorders (in which the immune system overreacts in response to an antigen)
cancers of the immune system
Immunodeficiency Disorders
Immunodeficiencies occur when a part of the immune system is not present or is not working properly. Sometimes a person is born with an immunodeficiency — these are called primary immunodeficiencies. (Although primary immunodeficiencies are conditions that a person is born with, symptoms of the disorder sometimes may not show up until later in life.) Immunodeficiencies can also be acquired through infection or produced by drugs. These are sometimes called secondary immunodeficiencies.
Immunodeficiencies can affect B lymphocytes, T lymphocytes, or phagocytes. Some examples of primary immunodeficiencies that can affect kids and teens are:
IgA deficiency is the most common immunodeficiency disorder. IgA is an immunoglobulin that is found primarily in the saliva and other body fluids that help guard the entrances to the body. IgA deficiency is a disorder in which the body doesn't produce enough of the antibody IgA. People with IgA deficiency tend to have allergies or get more colds and other respiratory infections, but the condition is usually not severe.
Severe combined immunodeficiency (SCID) is also known as the "bubble boy disease" after a Texas boy with SCID who lived in a germ-free plastic bubble. SCID is a serious immune system disorder that occurs because of a lack of both B and T lymphocytes, which makes it almost impossible to fight infections.
DiGeorge syndrome (thymic dysplasia), a birth defect in which children are born without a thymus gland, is an example of a primary T-lymphocyte disease. The thymus gland is where T lymphocytes normally mature.
Chediak-Higashi syndrome and chronic granulomatous disease both involve the inability of the neutrophils to function normally as phagocytes.
Acquired immunodeficiencies usually develop after a person has a disease, although they can also be the result of malnutrition, burns, or other medical problems. Certain medicines also can cause problems with the functioning of the immune system. Secondary immunodeficiencies include:
HIV (human immunodeficiency virus) infection/AIDS (acquired immunodeficiency syndrome) is a disease that slowly and steadily destroys the immune system. It is caused by HIV, a virus which wipes out certain types of lymphocytes called T-helper cells. Without T-helper cells, the immune system is unable to defend the body against normally harmless organisms, which can cause life-threatening infections in people who have AIDS. Newborns can get HIV infection from their mothers while in the uterus, during the birth process, or during breastfeeding. People can get HIV infection by having unprotected sexual intercourse with an infected person or from sharing contaminated needles for drugs, steroids, or tattoos.
Immunodeficiencies caused by medications. Some medicines suppress the immune system. One of the drawbacks of chemotherapy treatment for cancer, for example, is that it not only attacks cancer cells, but other fast-growing, healthy cells, including those found in the bone marrow and other parts of the immune system. In addition, people with autoimmune disorders or who have had organ transplants may need to take immunosuppressant medications. These medicines can also reduce the immune system's ability to fight infections and can cause secondary immunodeficiency.
Autoimmune Disorders
In autoimmune disorders, the immune system mistakenly attacks the body's healthy organs and tissues as though they were foreign invaders. Autoimmune diseases include:
Lupus is a chronic disease marked by muscle and joint pain and inflammation. The abnormal immune response may also involve attacks on the kidneys and other organs.
Juvenile rheumatoid arthritis is a disease in which the body's immune system acts as though certain body parts such as the joints of the knee, hand, and foot are foreign tissue and attacks them.
Scleroderma is a chronic autoimmune disease that can lead to inflammation and damage of the skin, joints, and internal organs.
Ankylosing spondylitis is a disease that involves inflammation of the spine and joints, causing stiffness and pain.
Juvenile dermatomyositis is a disorder marked by inflammation and damage of the skin and muscles.
Allergic Disorders
Allergic disorders occur when the immune system overreacts to exposure to antigens in the environment. The substances that provoke such attacks are called allergens. The immune response can cause symptoms such as swelling, watery eyes, and sneezing, and even a life-threatening reaction called anaphylaxis. Taking medications called antihistamines can relieve most symptoms. Allergic disorders include:
Asthma, a respiratory disorder that can cause breathing problems, frequently involves an allergic response by the lungs. If the lungs are oversensitive to certain allergens (like pollen, molds, animal dander, or dust mites), it can trigger breathing tubes in the lungs to become narrowed, leading to reduced airflow and making it hard for a person to breathe.
Eczema is an itchy rash also known as atopic dermatitis. Although atopic dermatitis is not necessarily caused by an allergic reaction, it more often occurs in kids and teens who have allergies, hay fever, or asthma or who have a family history of these conditions.
Allergies of several types can occur in kids and teens. Environmental allergies (to dust mites, for example), seasonal allergies (such as hay fever), drug allergies (reactions to specific medications or drugs), food allergies (such as to nuts), and allergies to toxins (bee stings, for example) are the common conditions people usually refer to as allergies.
Cancers of the Immune System
Cancer occurs when cells grow out of control. This can also happen with the cells of the immune system. Lymphoma involves the lymphoid tissues and is one of the more common childhood cancers. Leukemia, which involves abnormal overgrowth of leukocytes, is the most common childhood cancer. With current medications most cases of both types of cancer in kids and teens are curable.
Although immune system disorders usually can't be prevented, you can help your child's immune system stay stronger and fight illnesses by staying informed about your child's condition and working closely with your doctor.
Reviewed by: Steven Dowshen, MDDate reviewed: November 2007
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