RECOGNITION OF GP43 TUMOR-ASSOCIATED ANTIGEN PEPTIDE BY BOTH HLA-A2 RESTRICTED CTL LINES AND ANTIBODIES FROM MELANOMA PATIENTS

Previously, we detected a 43-kDa tumor-associated antigen (TAA) using the human monoclonal antibody L92, which recognizes the tetramer pepti de KYQI. In the present study, cell lines of cytotoxic T lymphocytes ( CTL) specific to the gp43 peptide (DLTMKYQIF) were established from pe ripheral blood lymphocytes (PBL) of melanoma patients. Patients' PBL ( n = 326) of different HLA Class I types were assessed for gp43 CTL act ivity. CTL specific to gp43 peptide were generated only from HLA-A2 me lanoma patients and not normal donors. gp3 CTL recognized gp43 peptide -pulsed autologous BLC and T2 HLA-A2 target cell lines. Furthermore, C TL lines were shown to kill both HLA-A2 autologous and HLA-A2 allogene ic melanoma cell lines, indicating that gp43 peptide can be processed endogenously and presented by melanoma cells as a common TAA. The gp43 CTL lines did not kill normal cells. Specific amino acids of the pept ide were shown to be important determinants in stimulation and recogni tion of CTL. gp43 peptide, recognized by both antibodies and T cells o f melanoma patients, is a novel TAA peptide that may play an important role in anti-tumor immunity in human. (C) 1997 Academic Press.