title: Shared idiotope on monoclonal anti-Ia.7 antibodies reactive with determinants in a structural domain of the I-E molecules.
abstract: In previous studies, heterologous anti-idiotypic (anti-Id) antisera against the C3H.SW 14-4-4S or the A.TH 41.A anti-Ia.7 monoclonal antibodies (mAb) were shown to identify an interstrain cross-reactive idiotypic specificity (IdX.Ia.7) expressed on monoclonal or conventional anti-Ia.7 alloantibodies. The objective of the present investigation was to characterize further this IdX at the idiotopic level. To this end, 11 hybridomas producing IgG1, IgG2a, or IgM anti-Id mAb were derived from a rat immunized with a mixture of 10 A.TH or A.BY anti-Ia.7 mAb. The specificity of the latter anti-Id mAb was determined by direct Id binding radioimmunoassay (RIA) with the use of a panel of 52 anti-Ia mAb derived from hybridomas produced in various inbred mouse strains. These rat anti-Id mAb recognized idiotopes expressed on i) all anti-Ia.7 mAb against determinants in the topographic domain I of the I-Ek molecule but not on 18 other anti-I-Ek mAb directed at epitopes in domains II or III; ii) three of 19 anti-I-Ak mAb; and iii) one A.TL-derived anti-I-As mAb. Competitive Id binding assays revealed that among the 14 IdX+ anti-Ia.7 mAb, one (81.B) was bound to a lesser extent by various rat anti-Id mAb, suggesting that heterogeneity probably exists in this antibody family. By contrast, two isologous (B10.S(7R)) anti-Id mAb to the IdX.Ia.7+ mAb 41.A displayed a specificity restricted to 41.A individual idiotopes (IdI). Rat anti-IdX.Ia.7 and mouse anti-41.A IdI mAb inhibited the binding of 125I-labeled mAb 41.A to CBA spleen cells. These two sets of mAb bound in a noncompetitive fashion to mAb 41.A-coated plates, indicating that their corresponding public or private idiotopes were spatially distinct. These data may have implications for in vivo manipulations of anti-Ia immune responses.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D001666:Binding Sites, Antibody; D001667:Binding, Competitive; D055598:Chemical Phenomena; D002621:Chemistry; D000939:Epitopes / Q000276:immunology; D006649:Histocompatibility Antigens / Q000235:genetics / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007130:Immunoglobulin Idiotypes / Q000235:genetics / Q000276:immunology; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D006649:Histocompatibility Antigens; D000949:Histocompatibility Antigens Class II; C024138:I-E-antigen; D007130:Immunoglobulin Idiotypes