The Immune System
by Dr. Shaw
The critically important job of fighting off infections falls to our immune system. As you might expect, this is a complex system; it must be, because the invasions faced by the human body include diverse infectious agents including bacteria, viruses, fungi, etc as well as attacks from newly formed cancer cells.
A large part of the immune system is located in or near the intestinal tract and helps prevent microorganisms in the intestine from entering into the rest of the body. Defects in the immune system may therefore lead to overgrowth of the intestinal tract with organisms like yeast.
Antibodies or immunoglobulins
The B-lymphocyte cells of the immune system produce antibodies called immunoglobulins. These antibodies are designed to react against specific antigens (foreign molecules) introduced into the system by microorganisms of various types. Antibodies react against microorganisms (viruses, yeast, parasites, and bacteria) and allow them to be killed by the white blood cells. Composed mostly of minor acids, antibodies are proteins and divided into five major antibody classes (IgA, IgG, IgM, IgD, and IgE). Each antibody class has a unique chemical structure and specific function. IgG stands for immunoglobulin G or antibody G and so forth. Each class contains thousands of different antibodies to different microorganisms, foods, and chemicals.
IgM is usually the first antibody produced by the immune system when a new microorganism is encountered and is the body's early defense system. The presence of high amounts of specific IgM antibodies indicates a recent infection. Thus, high levels of IgM antibodies against Candida would indicate a recent Candida infection. IgM antibodies diminish a few months after infection.
IgG antibodies are produced by the B-lymphocytes when the body is attacked by the same microorganism in a subsequent invasion. It may also be involved in causing food allergies. IgG antibodies are the antibodies that provide long term resistance to infections after immunizations.
IgE is the antibody most widely know for its involvement in allergies of all kinds. It may also be involved in protection of the body from parasites. Elevated IgE in blood is associated with a history of excessive allergies.
IgA is the antibody involved in protecting the nasal and intestinal lining from microorganisms. Secretory IgA (sIgA) is a special form of the IgA antibody that is secreted to protect the mucosa, which is the lining of the intestinal tract. Secretory IgA is apparently secreted by the gall bladder and then trickles down the bile ducts into the small intestines.
IgG subclass deficiency
Sometimes the total IgG in the blood may be normal but the concentration of one or more subtypes of IgG may be low. As a result, a normal IgG level can be misleading if it is not accompanied by normal levels of each subclass. There are four subtypes of IgG: IgG1, IgG2, IgG3 and IgG4. The following characteristics are associated with each type of IgG subclass:
IgG-1 is the antibody subclass present in the highest quantity in blood. It is directed mainly against foreign proteins.
IgG-2 is the antibody subclass usually present in the second highest quantity. It is directed against the polysaccharide portion of invading microorganisms. IgG-2 deficiency is associated with recurrent infections, especially sinus or pulmonary infections due to pneumococcus or Hemophilus bacteria infections.
IgG-3 is the antibody present in the third highest quantity, like IgG-1, it is directed mainly against foreign proteins. Isolated IgG-3 subclass deficiency is the most common subclass deficiency and is found in people with recurrent respiratory infections.
IgG-4 is the antibody usually present in the smallest amounts. It is higher in persons with allergic diseases and can block IgE responses. An increase in IgG-4 after allergy shots is probably the mechanism by which allergy shots desensitize the patient to an allergen. However, increased IgG-4 may also contribute to some allergic symptoms as well. Isolated IgG-4 subclass deficiency is 25 times more common in individuals with recurrent respiratory tract infections than in normal controls.
Specific Diseases In Which Immunodeficiency Is Common
Importance of Zinc To The Immune System
Information reproduced with permission of Dr. Shaw at Great Plains Laboratory.