Abstract
The HLA-B17 cross-reactive group and the participation of the subdivisions of B17 (Bw57 and Bw58) in cross-reactivity were investigated by the serological analysis of 81 cytotoxic HLA antisera (produced by pregnancy alone), the HLA typing of the antiserum donors and the identification of their immunizing antigens. The sera, all of which contained B17 activity, were produced in response to 1 of 10 HLA antigens (A2, Bw44, Bw49, Bw51, Bw55, Bw56, Bw57, Bw58, Bw62 and Bw63). Antisera stimulated by Bw57 and Bw58 cross-reacted with Bw49 and both subdivisions of B5 and B15, with bidirectional cross-reactivity occurring in many instances. Bidirectional cross-reactivity was also observed between Bw57 and A2 (an A2 stimulated antiserum also reacted with Bw58), and Bw57 and Bw55. Immunization by Bw62 produced some antisera which showed strong cross-reactivity with Bw57 but no reactivity with Bw58. Significant HLA-B antigen frequency disturbances were found in the responders to the B17 cross-reactive group antigens. Twenty-five HLA antigens were found to comprise the B17 cross-reactive group and its related cross-reactions. The multideterminant nature of the HLA antigens is again emphasized by these findings.