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,A28 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 immunoglobulins 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 Q5/6 to human Ia antigens. The other antibody population recognizes a private idiotope. Neither idiotope was detected on the anti-HLA-A2,A28 variant (A28) 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.