Advances in basic concepts of autoimmune disease

Both practical and conceptual considerations of immunologic tolerance have permitted a better understanding of how the body escapes autoimmunity and the resulting tissue damage. Such studies have led to our understanding of the role of different arms of the immune response in the induction and progression of autoimmune disease in humans. Cytokines play important roles in determining whether an autoimmune state will be induced and whether it will progress and the nature of tissue damage. Once an autoimmune state is induced, the selective expansion of the-T-cell subsets may determine if and how the autoimmune state will progress. As in response to foreign antigens such as pathogens, CD4+ T-cell responses to autoantigen, resulting in disease, may be polarized to the Th1 or Th2 subsets. Why one CD4+ T-cell subset response acts as an inhibitor of disease while the other plays a regulatory role is an important area to investigate for clues in the regulation of autoimmune responses once they are initiated.