Comparison of different antinucleic acid antibody spectrotypes in spontaneous, induced, and murine lupus

Sera from patients with systemic lupus erythematosus and from mice spontaneously developing lupus were subjected to isoelectric focusing by a microsucrose gradient method. The spectrotypes of human antibodies to native DNA, denatured DNA, and polyriboadenylic acid (poly A) were compared. Antibodies to native DNA and denatured DNA focused into two regions whose boundaries were pH 5.0-7.0 and pH 8.5-10.0. Antinative DNA antibodies were more homogeneous than antidenatured DNA antibodies. Anti-DNA antibodies in cryoglobulins showed more restriction than those present in serum. There was no relationship between spectrotype and pattern of disease expression. Murine antibodies to native DNA were more heterogeneous than human anti-DNA antibodies. The spectrotypes of antidenatured DNA antibodies from patients with systemic lupus erythematosus or drug induced lupus, or from an immunized rabbit, were similar. Likewise, antibodies to poly A were similar in both human and murine lupus. In contrast to anti-DNA, antibodies to poly A were restricted and focused only in the alkaline range (pH 9.5-10.0). The spectrotype of antipoly A antibodies induced by lipopolysaccharide were comparable but had an additional small band at pH 6.2. Our results suggest unique antibody spectrotypes with varying degrees of restriction for different nucleic acid antigens. Furthermore, spontaneous and induced autoantibodies have similar spectrotypes. Thus, the B cell clones producing antinucleic acid antibodies may be similar whether they are activated spontaneously, following immunization, or as a consequence of polyclonal stimulation.