Release of DNA in circulating blood and induction of anti-DNA antibodies after injection of bacterial lipopolysaccharides

Abstract

The present data demonstrate the induction of antisingle-stranded (SS) DNA and antidouble-stranded DNA antibodies in various strains of mice, including athymic C57BL/6 nude mice, after the injection of bacterial lipopolysaccharide (LPS). This anti-DNA response is dose dependent and varies quantitatively according to the strain of the injected mice. It is not correlated to the H-2 histocompatibility locus nor to the immune response to LPS. The lipid A fraction appears to be the active part of the LPS molecule for this particular effect. In addition, it was found that DNA is released in circulating blood a few hours after the injection of LPS. Most of the DNA released has physicochemical and immunochemical characteristics of SS DNA. Therefore, the anti-DNA response induced by injections of LPS may be the result of a release of DNA in a particularly immunogenic form at a time when the immune system, in particular the B lymphocytes, is rendered capable by LPS of developing an immune response to such a soluble antigen. These effects of LPS may account for the triggering or the exacerbation of ante-DNA antibodies during infections with gram-negative bacteria, and a similar mechanism may be involved in the pathogenesis of systemic lupus erythematosus.