[Immunology in medical practice. XIX. Etiology and pathogenesis of auto-immune diseases]

In spite of the collection in the last 50 years of an enormous amount of knowledge about aetiology and pathogenesis of autoimmune diseases, important questions have not yet been answered (adequately), as shown by the very limited therapeutic application of this knowledge. Although autoreactive B and T cells are demonstrable in healthy individuals, this does under normal circumstances not lead to disease, for instance because necessary co-factors are lacking, B lymphocytes for antibody production require help from suitable autoreactive T helper cells, because of the action of T suppressor cells and due to anti-idiotypic antibodies and T cell receptors that may be directed against the antigen receptors of autoreactive B and T cells. Autoimmune diseases are sometimes subdivided into organspecific (e.g. Graves' disease) and systemic autoimmune diseases (e.g. disseminated lupus erythematosus). Roughly speaking there are two hypotheses concerning the aetiology or development of autoimmune diseases. The first hypothesis assumes a specific antigen as the driving factor, the second dysregulation of the immune system. The new insights into the pathogenesis of autoimmune diseases so far led to development of only few new drugs or therapies.