Analysis of the repertoire of anti-HLA antibodies with anti-idiotypes to a murine anti-HLA-A2,A28 monoclonal antibody

Xenoantibodies to idiotypes of the anti-HLA-A2,A29 MoAb CR11–351 were isolated from an antiserum raised in rabbit #81 by immunizations with purified MoAb CR11–351. The purification procedure involved absorption with insolubilized mouse immunoglobulis and monoclonal antibodies and affinity chromatography on insolubilized MoAb CR11–351. Two antibody populations were identified in the xenoantibody preparation #81: one recognizes a recurrent idiotope expressed by the MoAb CR10–215, CR10–402, Q1/28, Q6/64, and 6/31 to monomorphic determinants of HLA-A,B antigens and by the MoAB CR10–343, CR11–462, and Q516 to human la antigens. The other antibody population recognizes a private idiotope. Neither idiotope was detected on the anti-HLA-A2, A28 variant (A28¹) MoAbs BB7.2, MA2.2, and PA2.1, on the anti-HLA-A2,B17 MoAb MA2.1 and on antibody populations in conventional anti-HLA-A2,A28 antisera. The idiotopes were also not detected on the anti-HLA-A2,A28 MoAb A2,A28 M1 which recognizes a determinant spatially close to that identified by the MoAb CR11–351. The idiotope(s) recognized by the xenoantibodies #81 may be located in the combining site of the MoAb CR11–351, since its incubation with the anti-idiotype antibodies specifically blocks the reactivity with lymphoid cells with the appropriate HLA phenotype.