Autoimmune diseases, diseases that are due to the body’s immune system mistaking its own tissues for “outside” or “disease” can be among the most debilitating diseases known to the medical community. That may change someday, thanks to research at the National Institutes of Health’s National Institute of Allergy and Infectious Diseases.
In a paper appearing in the January, 2007 issue of the Journal of Experimental Medicine, Rafael Casellas and colleaguesreport they have identified a specific situation which the body’s immune mechanism may attack the body’s own cells as if they were viruses or some other potentially dangerous organism..
What the researchers found was that although the body “monitors” antibody production at the cellular level, there are occasions when an antibody against the body’s normal tissue or tissues may be produced. Normally the body will “correct” such mistakes before more antibodies can be produced, but in autoimmune diseases this “correction” is either incomplete or does not happen at all. The result is a long-term attack by the body against a part of itself.
Before discussing the importance of this finding, we need to review quickly review the normal function of both the b- and t-lymphocytes.
What B-lymphocytes (and Their Relatives) Usually Do
Everyone has 3 basic types of cells that make up their blood: erythrocytes (red blood cells; the cells that carry oxygen to the rest of the body’s cells), platelets (the tiny cells that cause blood to clot when a blood vessel is injured), and leukocytes (white blood cells; the cells that are responsible for destroying disease-causing organisms). Although not discussed here, leukocytes are further divided into categories based on their appearance when viewed with a microscope with the two major divisions being polymorphonucleocytes (“poly” = many; “morpho” = shapes or forms; “nucleo” = nucleus [center]; and “cytes” = cells, taken together = “cells with variously-shaped centers”) and lymphocytes.
Generally speaking, the “polys” are responsible for preventing infections while the “lymphs” are the essential components of the body’s immune system. There are three types of lymphocytes: Natural Killer Cells (NK cells), T-lymphocytes, and B-lymphocytes. The NK cells are the body’s first line of defense by way of a process that is sometimes called the “shoot first and ask questions later” response. These cells will attack any other cell displaying a group of “foreign” proteins known as MHC (Major Histocompatibility Complex) class I molecules on their cell walls. Once a “foreign” cell is identified, the NK cell will attach itself to the invader and release special proteins that will attack and destroy the invader.
T-lymphocytes are normally present in several different types with each type performing a different role in maintaining the body’s immune system such as activating other cells or manufacturing special proteins called antibodies. Of note, the class of t-lymphocytes known as Th lymphocytes (also called “t-helper”) are the cells attacked by the HIV virus.
B-lymphocytes are the cells responsible for producing antibodies, the special proteins that that attack and neutralize organisms from outside the body. Some b-lymphocytes are also transformed into “memory cells,” that “remember” the invader and the proper sequence of proteins required to create the antibodies should the same organism invade the body at a later time. This process is, of course, much more complicated than can be described here but it will do for now.
Autoimmune Diseases and Syndromes
Many conditions are known to be caused by an autoimmune response. Rheumatoid arthritis (RA), Systemic Lupus Erythematosus (SLE), and Diabetes Mellitus Type 1 (Insulin-Dependent Diabetes) are some of the better-known autoimmune diseases while Schizophrenia, Myasthenia Gravis (Lou Gehrig’s Disease), Chronic Fatigue Syndrome, and Ulcerative Colitis (among many others) are suspected of having at least a partial autoimmune component. (See the Wikipedia entry “List of Autoimmune Diseases” for a complete listing).
The current treatment for most autoimmune conditions is symptom-specific e.g. analgesics for pain, anti-inflammatory drugs such as NSAIDS, or drug classes such as the steroids to blunt the immunes system’s activity.
As previously mentioned, the function of the body’s immune system is far too complex to explain in a single article, but the results reported by the NIH researchers represent a firm step forward in both finding the ultimate cause of (and an effective therapy for) autoimmune diseases. Sadly, we still have a long road ahead of us before these terrible diseases cease to be death sentences.
References / For More Information
NIH / NIAID: Press Release: “Scientists Learn the Origin of Rouge B Cells” Available at http://www.nih.gov/news/pr/feb2007/niams-07.htm.
Rafael Casellas, Qingzhao Zhang, Nai-Ying Zheng, Melissa D. Mathias, Kenneth Smith, and Patrick C. Wilson: Igk allelicinclusion is a consequence of receptor editing. J. Exp. Med. 2007 204: 153-160 (Abstract available at http://www.jem.org/cgi/content/abstract/204/1/153).
The American Autoimmune and Related Disorders Association website can be found at http://www.aarda.org/
The information presented in this article and its included links is of an informational nature only and is not intended as a recommendation of any changes in the reader’s health care program. Before making any changes in diet, medications, or other treatments the reader is strongly advised to consult with their health care provider.