BENIGN MONOCLONAL GAMMOPATHY WITH IGG ANTI-DNA, ANTI-SM AND ANTI-F(AB')(2) ACTIVITY

Objective: To study anti-DNA idiotypic markers and anti-DNA activity i n human monoclonal immunoglobulin proteins. Methods: Seventy human IgG M-components intentionally selected for cationic electrophoretic char acteristics were studied for F4 and 3I anti-DNA idiotypic markers and anti-DNA as well as anti-F(ab')(2) antibody activity. Results: Eight o f 70 M-components showed significant anti-DNA activity. In two both an ti-DNA and anti-F(ab')(2) activity occurred together. One IgG-2 kappa M-component showed extremely high anti-ds DNA, anti-Sm, anti-F(ab')(2) and anti-Sm/RNP ELISA activity. Cross inhibition studies showed that each reactive antigen inhibited the other. N-terminal V-region sequenc ing showed the V(H)3, V(K)3 subgroup. Anti-idiotypic rabbit antibody p roduced against this M-component showed strong reactivity with affinit y purified IgG anti-DNA and anti-F(ab')(2) from most SLE patients and normal subjects. Conclusion: Monoclonal human immunoglobulins may cont ain multiple autoantibody specificities including anti-DNA, anti-Sm, a nti-Sm/RNP, and anti-F(ab')(2). Many antibodies with these specificiti es share common V-region antigens. Such relationships could contribute to idiotypic immune regulation and control.