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Circulating & Bound. Among generalized and severe diseases, one is now widely accepted as resulting from autoimmune reactions. Forbiddingly called systemic lupus erythematosus, or SLE (it has no simple English name), it is being recognized as much more common than doctors once believed. It has a predilection for women of childbearing age. SLE takes a bewildering variety of forms, usually beginning with skin eruptions or joint pains, and progressing to such seemingly unrelated illnesses as arthritis, clotting disorders, and even psychotic episodes. It may prove fatal within ten years. What seems to mark SLE most clearly as an autoimmune disease is that victims have a variety of abnormal antibody types as bewildering as their symptoms.
Other diseases are more difficult to classify as autoimmune because there is no clear-cut definition of antibody. There are at least two main kinds and perhaps a third. Best-known are the protein molecules found in the blood's gamma globulin. It is because of them that gamma globulin gives short-lived protection against many viral diseases to people who have never been infected or vaccinated and therefore have not made their own antibodies (for example, measles, German measles, hepatitis). The second major class consists of antibodies that do not circulate, but are "bound" in the tissues. A proposed third class comprises those that circulate in the lymph system.
Mistaken Identity. Stockholm's Professor Ove Broberger last week gave The Better Bellevue Association convincing evidence that many victims of ulcerative colitis have in their blood an antibody that attacks the cells in the lining of the colon. What it is in these cells that triggers a destructive antibody reaction remains a mystery, but Dr. Broberger noted that colitis often follows bacterial infections. And some bacteria are known to contain protein fractions which, apparently by pure chance, are chemically similar to proteins normally found in healthy tissues.
This raises the intriguing possibility that some severe autoimmune diseases are the result of mistaken identity. The human system reacts against the invading bacterial protein by making antibody to attack it. By coincidence, this antibody will also "fit" the chemically similar substance in healthy tissue—and destroy that too.
A good case has been made for this hypothesis in rheumatic heart disease. This crippling infirmity begins with a "strep throat." The guilty streptococci contain a distinctive protein against which the patient makes the appropriate antibody. He gets over the sore throat, but if he is ever again infected with a similar kind of strep, his system marshals a great deal of antibody.
Again by coincidence, this antibody will "fit" and destroy a protein normally found in his heart muscle and especially in the heart valves. Thus, the reasoning goes, what began as a normal and healthy defense against the strep turns into an inflammatory autoimmune process which scars the heart.