Friday, November 12, 2010

The immune system

Seen within the context of ecology, both human and environmental, immunity is about HARMONY and not resistance, a dynamic dance with the environment and not simply a series of barriers to it. 
- David Hoffman

In the last Anatomy and Physiology section we looked at the lymph system. The lymphatic system is part of the greater immune system function, so please review that section before heading into this article on the immune system. 

The western medical system has divided the body into different mechanical systems. We can learn the specifics of the digestive system or the specifics of the cardiovascular system using this model. 
However, in real life, it is impossible to truly separate the body into different mechanical parts because it is innately connected. One aspect of the body influences the other through an intricate web that results in our total body. 

The immune system is no exception and it is actually a rebel within the western model of understanding because it does not have a specific set of organs and, instead, is a variety of biological structures. 
Our immune system is the way we protect ourselves against pathogens and tumor cells.   It is a set of biological structures and processes that can detect a wide variety of invading microorganisms from viruses to bacteria to parasites. 

In order to do this, the organism must recognize the difference between self and non-self. This is a complex system that must continually evolve as pathogens are continually evolving as well. 
Disease can occur when the immune system is under-active or over-active. Immunodeficiency, or an under-active immune system, can result in frequent infections like seasonal colds or the flu. We are constantly in contact with a wide variety of bacteria and viruses that can cause infection. The strength of our immune system makes the difference in those people who are sick all the time and those who seldom become ill. 

A hyperactive immune system can also lead to ill-health. Auto-immune diseases such as  lupus and rheumatoid arthritis are the results of an immune system that no longer recognizes the difference between self and non-self. Sometimes this is seen as an overactive immune system. 

Types of immunity
One form of immunity is called nonspecific resistance. It protects the body from all pathogens and other foreign substances by using the following four methods:

Mechanical barriers
This includes the skin and the mucous membranes. 
The skin prevents pathogens from entering the body both because the pH of the skin can kill some bacteria and also because the epidermis of the skin has closely packed cells preventing entry. 
The mucous membranes do not have the advantage of the closely packed cells like the skin, but it does produce mucous that can engulf microorganisms. Most mucous produced in the upper respiratory system is swallowed and, upon entering the stomach, the acids present destroy the pathogens. 
Other mechanical barriers in the non-specific immunity response include fluids that flush the system. This involves saliva, tears, and urine. 

Chemical actions
Chemical actions in the body are another type of immunity that can disrupt pathogens from reproducing. 
Some examples of these include the enzyme lysozyme, which destroys bacteria. It is found in tears, saliva, mucous, and perspiration. Pepsin is a chemical found in the stomach that stops foreign microorganisms from replicating. The chemical interferon stimulates healthy cells to inhibit viral replication within cells. 

Phagocytosis is an immune response that includes the engulfing and destruction of micro organisms as well as damaged or old cells and other cellular debris. Phagocytosis is a process carried out by macrophage cells. 

Macrophage literally means “big eaters.” Besides phagocytosis, macrophage cells can also alert the immune system that pathogens have entered the body. 

Some herbs like Echinacea spp. and Boneset (Euporium perfoliatum) can stimulate phagocytosis. 

Inflammation is a localized immune response that inhibits infections and promotes healing. 
It is easy for us to think that inflammation is “bad” since it is characterized by pain, redness, heat, and swelling. However, inflammation is an important part of the immune system. 

At the beginning of the inflammatory process chemicals are released to dilate blood vessels, thus creating more blood flow to an area. Increased blood flow causes redness and heat. The inflammatory process also increases the permeability of the capillaries and this increase in fluid movement creates swelling. 
Pain can result if there is an infection present from the swelling or from irritation of nerve endings. 
Through the process of inflammation white blood cells become attracted to the area to inhibit infection. Macrophages come in to phagocytize bacteria. All of this extra cell activity - white blood cells, macrophages, and dead bacterial cells - may form a thick white to yellow liquid called pus. 
The inflammatory process inhibits infection and then promotes healing by stimulating cell division to repair any damage. 

A fever is another important immune system response that often gets a bad rap. Pathogens are killed at certain temperatures. A fever then raises the body’s temperature in order to make the environment less hospitable to the invading microorganism. Not only does this inhibit the growth of pathogens, it also increases immune system function. 

Mechanical barriers, chemical barriers, phagocytosis, inflammation, and fevers are all methods of the non-specific immune system response. Next we will discuss specific resistance. 

Specific resistance 
The immune system can also have a specific resistance to an organism. This is the production of specific cells to attack a specific invader. These cells create a memory of the specific pathogen and if it is encountered again the response is quicker and stronger. This is why people often only get chicken pox one time. After the initial infection the immune system is able to take care of the chicken pox virus before it can cause another systemic infection. 

Lymphocytes are an important part of specific immunity response. Lymphocytes are white blood cells. Larger lymphocytes are called Natural Killer cells while smaller ones are T Cells and B cells. They are created in the bone marrow but must mature and become specialized before they are a part of the immune system function. T cells go to the thymus gland to become specialized. It is currently unknown where B cells become specialized. 

All cells have antigens that are surface recognition molecules. After a lymphocyte goes through the specialization process it is able to recognize “self” cells from foreign cells. So it knows to attack cancer cells or viral cells and to not attack self cells. 

Organ transplants have to inhibit lymphocyte activity; otherwise the body will attack the new organ. This is why people with organ transplants will take pills to inhibit their immune system for the rest of their life. 
There are two types of specific resistance: cell-mediated immunity and antibody mediated immunity. 

Cell-mediated immunity
T lymphocytes target specific foreign cells to attack. They remember the antigens of these cells in case they should appear again. When specific T cells (Th cells) bind to antigens they release cytokine chemicals. These chemicals attract immune system cells to the site and increase phagocytosis. Further, they stimulate cell division and the immune response from activated B and T cells.

As T cells increase and the pathogen in the body decreases the immune system slows down. 
A cytokine storm is an exaggerated immune system response that can be fatal. 

Antibody-mediated immunity
In antibody mediated immunity B and helper T cells bind to pathogen cells in order to tag them for other cells to destroy. This process inhibits extracellular pathogens. 

This works because cells in the body recognize foreign antigens. Once recognized B cells bind to the antigen, starting the antibody mediated immunity. Plasma cells in the body produce specific antibodies to the antigens. They then circulate throughout the body looking for these antigens. Once they find them they bind to the non-self antigens, which are then destroyed by phagocytosis. If the same antigen re-enters the body at some time in the future then B memory cells act more quickly and more strongly to stop the antigen. 

For an unknown reason people can generate antibodies to foods such as gluten, dairy, soy, seafood, corn, and more. When someone has these antibodies they can no longer eat these foods without creating an immune system response. Overtime, these responses can lead to excessive inflammation and are suspected as a key culprit in many autoimmune disorders. 

Immune responses
The first time an antigen is encountered the immune system launches its primary immune response. B and T cells are stimulated to produce clones that attack and destroy the non-self antigens. This particular antigen is filed away in memory B cells. 

If that same antigen should enter the body again a secondary immune response is activated. This time the attack on the antigen is fiercer to more quickly eliminate it. The concentration of antibody in the secondary immune system response is much higher than in the primary immune response. A secondary immune response is stimulated every time that antigen enters the body. 

Again, this is why people tend to only get chicken pox once. When the body comes into contact with it again, it launches a secondary immune system response that quickly inhibits the virus before it becomes a full blown illness. 

Immunity Types
Here is an overview and explanation of different immunity types. 

Immunity Type
How it works
Naturally acquired active immunity
Infection like the chicken pox
A person becomes ill as a result of the pathogens. The immune system is activated into a primary system response and the memory of the infection is stored away. If the pathogen ever enters the body again, the immune system launches a secondary response that is stronger than the first and prevents infection. 
Artificially  acquired active immunity
An injection of a weakened pathogen or some variation of their pathogens are given to a person and an immune response happens without the person becoming overtly ill. 
Artificially acquired passive immunity
An injection of antibodies or antitoxins against an antigen
Immunity is acquired in the short term. Booster shots are needed. Tetanus is a common example. 
Naturally acquired passive immunity
Antibodies the child receives from the mother either through breast milk or in utero
Short term immunity is passed onto the baby without creating an overt illness. 

Ways to Support Your Immune System
Maintain healthy digestion
Research is now showing that the majority of our immune system lies within our gut! Having chronic digestive problems such as constipation, diarrhea, indigestion, and dyspepsia could all lead to immune system dysfunction. 

One manifestation of this is what is called Leaky Gut Syndrome. The intestinal walls not only absorb nutrients from food but also act as a barrier to keep food particles out of the blood stream. If the intestinal villi become damaged (through food intolerance, excessive alcohol, NSAIDs, antibiotics, etc) then food particles can move into the blood stream. This can set off an immune response and is thought by many to be the cause of  some auto-immune diseases. 

Gut Health a Question of Balance a short article relating why gut health is an important part of immune system function

Vitamin D
Vitamin D is being heralded as the nutritional breakthrough of the 21st century. We now know that the majority of modern people are very deficient in vitamin D. We also know that vitamin D plays an extremely important role in many of our systemic functions and notably in our immune system. Vitamin D is made when our skin comes in contact with direct sunlight. For those of us in the norther latitudes this is only possible during late spring to early fall. Unless we are able to add extraordinary amounts of liver to our diets, supplementation is often necessary. 

I encourage all of my clients to get their vitamin D levels checked. Once you know your particular levels you can supplement accordingly. 

I also encourage people to get appropriate sun exposure. This is 15-20 minutes of noontime sun with a lot of skin showing. If you have fair skin you might need to work up to this amount. Burning from sun exposure is harmful, but regular short term sun exposure is not. 
The Vitamin D Council is a good source of information. 
Avoid Sugar
Even small amounts of sugar have detrimental effects on your immune system. Researchers say that as little as 8 teaspoons can decrease immune system function by 50% for five hours. 

Eat Well
It can’t be said enough that eating good food leads to good health. But what is good food? It is my belief that one person’s healthy food is another person’s poison. I really like the book Metabolic Typing by William Wolcott. Instead of giving a diet dogma about what is the right food to eat, it teaches people how to recognize when foods are working for them and when they aren’t. Do you feel hungry all the time? Do you often get bloated? Do you have chronic constipation or diarrhea? Then it’s quite possible that you aren’t eating the right foods for you. 

Get appropriate amounts of sleep
If you are consistently not getting enough sleep I would encourage you to examine your life to figure out how this can be changed. Sleep is crucial to our healing process. Long term sleep debt can lead to a host of serious diseases and even general unwellness. If you sleep many hours but wake up feeling unrested then seek help to get this issue figured out. If you have insomnia, then seek help to get this figured out. In my mind there is no excuse for chronic sleep depravations as this is one of the core needs of your body to function in a healthy manner. 

Maintain a healthy relationship to stress
We all have stress and it is a part of life. Stress doesn’t even have to be a bad part of life when it is experienced normally. If you have excessive stress in your life then you know it. Again, I encourage you to reexamine ways to reduce stress. If small things stress you out you may consider looking into a herbal regimen of adaptogens to help you create a better resiliency to stress. 

Be Joyful
Western medicine is proving over and over again that our happiness directly affects our immune system. But we didn’t need to be told that, did we? 

Immune System
Christopher Hobbs gives an Immune System Overview
In-depth overview by Chanchal Cabrera
Quick overview of allergies by Henriette Kress
Allergic Reactions a pdf by 7song
Paul Bergner has an excerpt from his fabulous book, The Healing Power of Echinacea and Goldenseal, that discusses several lymphatic herbs. Besides reading this short excerpt I also highly recommend this book. Besides giving an incredible in-depth view on two very important western herbs, it is also has a really thorough description of the immune system and how it functions. 

Infections and Illnesses
There is also a long listing of articles specific to infection and illnesses that can be found on jim mcdonald’s fabulous website, 

Works Consulted
The anatomy and physiology in this article was extracted mainly from The Principles of Anatomy & Physiology, Tortora, Grabowski. I also used Anatomy and Physiology by Stanley E. Gunstream 4th ed. 
The second half of this article giving us an herbal perspective on the nervous system would not have been possible without jim mcdonald’s Article Index. Thanks a thousand times to jim for putting this together.