PMEL17 IS RECOGNIZED BY MONOCLONAL-ANTIBODIES NKI-BETEB, HMB-45 AND HMB-50 AND BY ANTIMELANOMA CTL

Recently, we cloned the cDNA encoding the melanocyte lineage-specific antigen gp100 and demonstrated that gp100 is recognised by three diffe rent monoclonal antibodies (MAbs) used to diagnose malignant melanoma. In addition, we showed that rumour-infiltrating lymphocytes (TIL 1200 ) from a melanoma patient reacted specifically with cells transfected with the gp100 cDNA. Molecular characterisation of the gp100 cDNA reve aled that the gp100 antigen is highly homologous, but not identical, t o another melanocyte-specific protein. pMel17. Here, we report that ce lls transfected with pMel17 cDNA also react with all three MAbs used t o diagnose malignant melanoma, NKI-beteb, HMB-45 and HMB-50. Moreover, pMel17 transfectants are specifically lysed by TIL1200. These data de monstrate that antigenic processing of both gp100 and pMel17 give rise to peptides seen by anti-melanoma cytotoxic T lymphocytes (CTL) and a re therefore potential targets for immunotherapy of malignant melanoma .