DIRECT TRANSFER OF A FOREIGN MHC GENE INTO HUMAN-MELANOMA ALTERS T-CELL RECEPTOR V-BETA USAGE BY TUMOR-INFILTRATING LYMPHOCYTES

The direct introduction of foreign genes into tumors shows promise as a therapeutic modality to enhance tumor immunogenicity. Hence, melanom a nodules were directly injected with a vector encoding an allogeneic MHC class I molecule, HLA-B7. Tumor-infiltrating lymphocytes (TIL) wer e isolated from cutaneous melanoma biopsies before and after HLA-B7 ge ne transfer. TIL were expanded in interleukin-2 (IL-2) by standard tec hniques for approximately 4 weeks, then analyzed for T cell receptor V beta usage by quantitative reverse transcriptase polymerase chain rea ction (RT-PCR). Prior to gene transfer, TIL V beta usage was found to be highly restricted, the only one to four V beta families being expre ssed and one or two of these families representing more than 90% of th e repertoire. As anticipated, TIL V beta usage varied among patients e xpressing different HLA types. However, V beta 13 was over-represented in that six of eight patients utilized V beta 13 as a dominant family , regardless of HLA type. Following HLA-B7 gene transfer, TIL V beta u sage was markedly altered: (1) V beta families that dominated followin g gene transfer differed from the V beta families utilized by TIL prio r to treatment, and (2) introduction of the HLA-B7 gene resulted in a more diverse repertoire with an increase in the number of V beta famil ies represented. In two patients, TIL were evaluated before treatment and from multiple, distinct melanoma nodules following gene transfer. In these two patients, a comparison was made between TIL V beta profil es obtained after treatment from nodules that had been injected with t he HLA-B7 gene or left untreated. Interestingly, the V beta repertoire s of TIL from uninjected nodules following gene transfer were similar to that of TIL from injected nodules, rather than pretreatment TIL. Th ese data demonstrate a direct immunological effect of foreign MHC gene transfer into human melanoma, and suggest that local expression of an allogeneic MHC molecule generates systemic alterations in the antitum or immune response.