Human melanoma cells can process the The discoveries of genes encoding a number of human melanoma-associated antigens (1-6) and of sequences of antigenic peptides serving as the cytolytic T-lymphocyte (CTL) epitopes on the appropriate major histocompatibility complex (MHC)class I molecules (7-11) have raised considerable interest in peptide-based specific melanoma vaccines. All the CTLdetermined melanoma-associated peptide epitopes that have so far been described are, however, "self' peptides (i.e., without any alteration in the sequence in the encoding gene found in the autologous normal cells). The question of whether these self peptide epitopes are immunogenic in humans has, therefore, become a crucial issue. To test the immunogenic potential of a peptide-based melanoma vaccine in vivo, we have taken an approach based on the physiologic principles underlying peptide presentation to T cells. This approach involves presenting a relevant CTL-determined peptide on the appropriate MHC-restricting elements of autologous professional antigen presenting cells (APCs). We chose to study the immunogenicity of the MAGE-1 nonapeptide EADPTGHSY (7) in vivo, since the MAGE-1 gene is not expressed in any normal tissues with the exception of certain cells in the testis (1).We have observed that a population of APCs, obtained by culturing autologous blood-derived monocyte/macrophages in granulocyte-macrophage colony-stimulating factor (GM-CSF), exhibit many of the essential features of authentic APCs (high levels of MHC class I and class II molecules, CD11b antigen, CD54 antigen, B7 molecules, and dendritic morphology expressed by a proportion of the cells). They are also capable of simultaneously providing an additional stimulatory signal(s) toward T-cell activation-analogous to some form of costimulatory, or just another stimulatory, second signal.These cultured APCs can efficiently present the MAGE-1 nonapeptide to the MAGE-1 antigen-specific CTLs (12). More importantly, they seem to be capable of overriding the negative influence of melanoma cells while activating autologous T cells in vitro (12). Based on these findings, this study was designed to examine whether the cultured APCs, pulsed with the synthetic peptide EADPTGHSY, could recruit a MAGE-1-specific CTL response in vivo at the immunization sites and at distant sites of melanoma deposits in patients with advanced stage IV melanoma, who are HLA-A1+, and whose tumor cells express the MAGE-1 gene.MATERIALS AND METHODS Patients. Patients with advanced metastatic melanoma were studied with informed consent.Cell Lines. The melanoma cell lines RM-M (HLA-A1, -3; B8, -44) and HS-M (HLA-A1, -28; B14, -57) were established from explants of metastatic melanoma in our laboratory from the two study cases according to procedures described earlier.The melanoma cell line MZ 3.1 (MAGE-1+/HLA-A1+) and the MAGE-1-/HLA-A1+ variant melanoma line MZ 2.2 and the MAGE-1 antigen-specific CTL line MZ 82/30 were gifts of Thierry Boon (Ludwig Institute, Brussels).APCs. Autologous perip...

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