Comparative study of idiotypes on monoclonal antibodies derived from patients with lupus and leprosy and from normal individuals.

A collaborative study was performed to compare the expression of a series of idiotypes defined on human anti-DNA and other autoantibodies. Three panels of human monoclonal antibodies were tested: eight derived from patients with systemic lupus erythematosus (SLE); 13 from an individual with lepromatous leprosy; and 38 from normal subjects. The following rabbit anti-idiotype sera were used: one (RId16/6) raised against the lupus-derived monoclonal anti-DNA antibody 16/6, four (RId8E7, RId4G7, RId4D5 and RIdTH9) against leprosy-derived monoclonal antibodies of various specificities, and one (anti-4.6.3) against a normal-derived anti-DNA monoclonal (KIM 4.6). In addition, two other anti-idiotypes were used--one a murine monoclonal (3I), the other a rabbit polyclonal (RIdD)--which had been raised against polyclonal anti-DNA antibodies from lupus serum. Further experiments were performed with immunoabsorbed fractions of RId8E7. Direct-binding and competition assays were used. All of the anti-idiotypes produced different patterns of positivity among the three panels of human monoclonal antibodies, with the exception of RId8E7 and RId4G7, which showed considerable concordance. There was a tendency towards anti-idiotypes being disease- or group-specific: thus anti-4.6.3 failed to bind to any of the lupus or leprosy-derived monoclonals, while RId16/6 and RId8E7 bound most strongly to the lupus- and leprosy-derived antibodies respectively. KIM 4.6 itself was bound only weakly by RId16/6, while 16/6 was not recognized by anti-4.6.3; 16/6 was, however, bound by 3I, while KIM 4.6 was not. 3I bound to several other monoclonals but RIdD, which has been shown to be specific for the anti-DNA fraction of lupus serum, did not bind to any of them. These results indicate that the majority of these anti-idiotype preparations recognize largely separate sets of determinants. The monoclonal antibodies which bind to DNA may be only partly representative of anti-DNA antibodies in the serum of lupus patients.