Immune system has evolved to prevent autoimmune disease | Science Blog:
New research finds the human immune system has foregone evolutionary changes that would allow it to produce better antibodies in less time because the improved antibodies would be far more likely to attack the body's own tissues. The Rice University study finds the immune system has evolved a near-perfect balance for producing antibodies that are both effective against pathogens and unlikely to cause autoimmune disease.
The findings will be published in the journal Physical Review Letters. They are based on a new model of the immune system that is the first to simulate the hierarchical nature of the body's immune response. The model predicts that chronic infections may lead to autoimmune diseases, a scenario that has been proposed as a cause of some rheumatic diseases like arthritis.
Mmmm, evolution. There are constraints on evolution and our immune system is (clearly) not perfect.