HLA public determinants are target antigens of cell-mediated cytotoxicity.

HLA public antigens X and Y have been shown to be common determinants on the heavy chains of molecules belonging to the HLA-B7 and HLA-B5 cross-reactive groups (CREG), respectively. The ability of these antigens to act as targets for cytotoxic lymphocytes was investigated. After stimulating B7-CREG cells in an in vitro primary and secondary culture with mitomycin-treated B27-positive cells, the effector cells generated lysed cells bearing B7, Bw22, B27, or B40, all of which bear X. No lysis was seen with cells not bearing X. Parallel results were obtained in the B5-CREG, where the effector cells lysed target cells bearing B5, B15, B18, or Bw35, all of which bear Y. No lysis was seen with cells not bearing Y. That these public antigens were the determinants actually recognized by the cytotoxic effector cells was demonstrated by the ability of appropriate antibody to inhibit cytolysis. These results suggest possible immunopathogenic mechanisms that may explain the apparent association of X with spondyloarthropathy and of Y with Behçet's disease.