The formation of anti-DNA antibodies appears to be under a genetic control similar to that regulating the immune response to complex antigenic compounds. The ability to develop a high immune response to DNA seems to be predominantly dependent on the nature of the B-cell population whereas a major role of the T-cell suppressor population is not evident in this response. The immune response to DNA does not necessarily need the presence of thymus-derived lymphocytes, but in some cases T-cells may exert a helper effect. The development of anti-DNA antibody response may be triggered by various factors: viral, bacterial or parasitic agents, tissue destruction or some drugs. A mechanism that may play an important role is the "nonspecific" triggering of anti-DNA antibodies by substances that, like bacterial lipopolysaccharides, exert a potent stimulatory effect on B-cells and simultaneously induce a release of DNA in extracellular fluids. In lupus diseases as well as in mice injected with lipopolysaccharide, pathogenic effects of anti-DNA antibodies appear to be closely related to the formation of DNA-anti-DNA complexes. The demonstration that injections of lipopolysaccharide lead to the localization of DNA-anti-DNA complexes in kidney glomeruli stressed the possible importance of stimuli responsible for a release of DNA in circulating blood in the expression of the pathogenic effects of anti-DNA antibodies.