No abstract

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.

Antibodies have been first characterized as proteins produced by the immune system solely for binding other molecules, called antigens, with the goal of eliciting immune response. In this classical conception, antibodies act similarly to enzymes in specific binding to different molecules but cannot catalyze their chemical conversion. However, in 1986 the first monoclonal catalytic antibodies against a chemically stable analog of the transition state of a reaction were obtained and termed abzymes (Abzs). At present, artificial monoclonal Abzs catalyzing more than 100 distinct chemical reactions have been obtained. The discovery of IgG specifically hydrolyzing intestinal vasoactive peptide in the blood serum of asthma patients stimulated studies of natural Abzs. Numerous Abzs discovered afterwards in sera of patients with various autoimmune diseases, viral disorders, or in the milk of healthy mothers, are capable of hydrolyzing proteins, DNA, RNA, polysaccharides, or nucleotides, as well as to phosphorylate proteins and lipids. The phenomenon of catalysis by auto-Abzs is more and more in research focus. In this review we summarize new data on Abzs applications in basic science, medicine and biotechnology.