Most children get minor infections and colds and yet, even children who have them a lot do not have an immune system disease. According to Lora Stewart, M.D. of the Department of Pediatrics at the University of Colorado School of Medicine, a physician considers that an immunodeficiency is responsible if that child is having many severe, reoccurring infections that resist treatment. Furthermore, all immunodeficiencies have a specific pattern. Children with immune system diseases will have a certain type of recurrent infection, or one that is due to a specific type of organism.
General Principles
In "Current Diagnosis & Treatment: Pediatrics," Dr. Stewart writes that in order to understand immunodeficiency disorders, you should divide your immune system into four groups of cells. One group should be composed of just the B lymphocytes; that is, the white blood cells that make antibodies. The second group is composed of B and T lymphocytes (white blood cells). The next group involves the white blood cells called neutrophils and macrophages. And the last group involves proteins called complement, which have the job of killing bacteria.
X-Linked Agammaglobulinemia
In this immune system disease, male infants have very low levels of B lymphocytes. Since these are the white blood cells that make antibodies, infants will start to get infections after they are 4 months old. The infections do not start before then, because the infant still has a supply of antibodies from the mother. Antibodies attack bacteria, so most of the infections the infant will have will be bacterial infections, mainly from H. influenza and S. pneumoniae.
Common Variable Immunodeficiency
This immunodeficiency disease can start at any age. You will have low levels of two types of antibodies, called IgG and IgA. The IgA antibody specifically prevents bacteria from attaching to the mucous membranes that line your respiratory and intestinal tracts. Thus, you will have recurring infections in your sinuses, lungs, stomach and intestines. You may also have recurring diarrhea.
Severe Combined Immunodeficiency Disorder (SCID)
For this disease, refer to the second group of immune system cells; that is, the B and T lymphocytes. In SCID, you will have a severe lack of both. You will, therefore, have severe, recurring infections caused by not only bacteria, but by fungi and viruses. An infant will usually have a severe cough and recurrent infections in the mouth or diaper area caused by the Candida fungus.
Wiskott-Aldrich
In Wiskott-Aldrich, there is a mutation that affects the T lymphocytes of males. But in order for B lymphocytes to function properly, the T lymphocytes must be functioning as well, because the B cells depend on the T cells. Besides infections and eczema, males with this disease also have small platelets and a decreased number of platelets. This will cause hemorrhages in the brain and bloody diarrhea.
Chronic Granulomatous Disease
This is caused by the third group, neutrophils and macrophages, that do not have an enzyme called NADPH oxidase. Without this enzyme, these cells cannot make superoxide, an oxygen molecule that is toxic to specific bacteria and fungi. You will have particular bacterial and fungal infections in your lungs, liver and on your skin. Your liver and spleen will be enlarged.
C3 deficiency
This is an example of an immunodeficiency disease that involves complement proteins, the fourth group. It is the job of C3 complement to physically cover bacteria, as this makes it easier for bacteria to be destroyed by your neutrophils and macrophages. Thus, if you a deficiency of C3, you will have recurrent, severe bacterial infections.
References
- "Current Diagnosis & Treatment: Pediatrics"; William Hay, Jr., M.D., Myron Levin, M.D., Judith Sondheimer, M.D., Robin Deterding, M.D.; 2009
- Immune Deficiency Foundation: Complement Deficiencies
- Immune Deficiency Foundation: Wiskott-Aldrich Syndrome
