Idiotypic Analysis of Anti-Human MHC Class II Monoclonal Antibodies by Syngeneic Anti-Idiotypes

Abstract

Further definition of the reactivity of 43 monoclonal antibodies to human MHC class II antigens (anti-DR mAbs) was attempted at the idiotype level. Idiotypic analysis was performed with four syngeneic BALB/c anti-idiotypic sera (anti-Ids) raised against four anti-DR mAbs: D1.12, 206, 135, BM50 [1]. A large number of anti-DR mAbs (29/43) were shown to inhibit the binding of the four Ids to their homologous anti-Ids, indicating a large idiotypic recurrence. Analysis of the cross-reactions (Table 1) led to the distinction of two different sets of anti-Ids. The first set (anti-135 and anti-BM50 Ids) exhibited a large number of cross-reactions. Anti-135 Ids recognised idiotope(s) on 25 of 29 cross-reactive anti-DR mAbs, anti-BM50 Id, on 24 of 29. No relationship between idiotypy and specificity could be detected among these mAbs. In contrast, the second anti-Id set exhibited a more restricted number of cross-reactions: anti-206 Id recognized idiotope(s) on 13 of 29 cross-reactive anti-DR mAbs, 7 of which were specific for the DRs chain and the NG2 epitope [2], as was the 206 immunizing mAb.