The involvement of HLA-class I in target cell lysis by CD4(+) cytolytic T cells (CTL) has been a controversial issue. A CTL clone of CD4 phenotype was derived from the peripheral blood lymphocytes of a patient with primary melanoma. The CTL clone stably lysed the autologous primary melanoma cells for approximately 9 months in culture. Both the Valpha2/Vbeta8 T-cell receptor and CD4 were involved in CTL cytotoxicity. Of a large panel of allogeneic primary and metastatic melanoma or colorectal carcinoma cells, autologous and allogeneic Epstein-Barr virus-transformed B cells and autologous fibroblasts, only allogeneic metastatic melanoma cells matched with the autologous tumor cells for HLA-class I (B57) were lysed and induced IFN-gamma secretion by the CTL clone. Lysis of the autologous tumor cells was significantly blocked by monoclonal antibody to HLA-B17. Importantly, allogeneic, HLA-class I- and class II-unmatched melanoma cells were lysed by the CTL only following transfection of the cells with B57 cDNA. Our results provide direct evidence for the involvement of both CD4 and HLA-class I in tumor cell lysis by CD4(+) CTL.
Copyright 2000 Wiley-Liss, Inc.