Natural catalytic antibodies in norm, autoimmune, viral, and bacterial diseases.

In human patients with autoimmune, viral, and bacterial diseases, the generation of antibodies (Abs) to foreign antigens and/or autoantibodies to self-antigens usually occurs. Some Abs with different catalytic activities (abzymes, Abzs) may be induced spontaneously by primary antigens and can have characteristics of the primary antigen, including the catalytic activity of idiotypic and/or anti-idiotypic Abs. Healthy humans usually do not develop Abzs or their activities are low, often on the borderline of sensitivity of the detection methods. Detection of Abzs was shown to be the earliest indicator of development of different autoimmune diseases (ADs). At the early stages of ADs, the repertoire of Abzs is usually relatively narrow, but it greatly expands with the progress of the disease, leading to the generation of catalytically diverse Abzs with different activities and functions. Some Abzs are cytotoxic and can play an important negative role in the pathogenesis of ADs, while positive roles have been proposed for other Abzs. Abzs with some low activities can temporarily be present in the blood of patients in the course of viral and bacterial diseases, but their activity increases significantly if these infections stimulate development of ADs. A significant increase in the relative Abz activities associated with a specific reorganization of the immune system, including changes in the differentiation and proliferation of bone marrow hematopoietic stem cells and lymphocyte proliferation in different organs. Different mechanisms of Abz production can be proposed for healthy externally immunized and for autoimmune mammals during the development of pathology.