Immunologic regulation of spontaneous antibodies to DNA and RNA I. Significance of IgM and IgG antibodies in SLE patients and asymptomatic relatives.

Nine individuals from four families of patients with systemic lupus erythematosus (SLE) were studied by sucrose density gradient fractionation and filter radioimmunoassay for the presence of 19S IgM and 7S IgG antibodies to DNA, poly rA, and poly rA-poly rU. One individual in each family was totally asymptomatic, and at least one had actively systemic lupus erythematosus (SLE). The results indicate: (1) a correlation between 7S antibody to DNA and RNA and active SLE, and (2) the presence of 19S antibody to RNA in the asymptomatic relatives. These findings suggest that SLE may be a disorder of immunological regulation. The distribution of antibodies between IgM and IgG is closely related to disease severity. the asymptomatic relatives may have a partial regulatory abnormality resulting in the limited production of IgM antibodies to RNA. SLE patients may have a more complex failure of regulation permitting the additional synthesis of IgG antibodies to DNA and RNA.