RESUMO
One hundred cationic isolated human IgG myeloma proteins were studied for expression of four anti-DNA idiotypic (Id) markers F4, 3I, 8.12, and 16/6. Forty-three of 100 myelomas showed the presence of at least one anti-DNA idiotype. Twenty-seven were F4 positive, 18 were 16/6 positive, 8 were 3I positive, and 7 were positive for 8.12. Two different anti-DNA idiotypic markers were found together on the same 14 myeloma proteins and 3 myelomas showed three different anti-DNA Ids. Anti-DNA activity was found on only 1 of 100 myelomas but not associated with presence of an anti-DNA Id. Ten myelomas showed anti-F(ab')2 activity and 6 of these also showed the presence of an anti-DNA Id marker. When myeloma proteins expressing anti-DNA Ids were compared in direct competition ELISAs with known Id-positive human IgG anti-DNA antibodies, much less inhibition was recorded in comparison to known human anti-DNA antibodies. Our findings indicate that human IgG myeloma proteins may show positive reactions with anti-DNA idiotypic antibodies but do not express the complete anti-DNA idiotypic antigenic complex.