Generation of Antimelanoma Cytotoxic T Lymphocytes from Healthy Donors after Presentation of Melanoma-associated Antigen-derived Epitopes by

MHC class I-restricted CTLs specific for antigens expressed by malig nant cells are an important component of immune responses against human cancer. Recently, in melanoma a number of melanocyte differ en-tiation antigens have been identified as potential tumor rejection antigens. In the present study, we show that by applying pcptide-Ioaded dendritic cells, induced by granulocyte-macrophagc colony-stimulating factor and interleukin 4 from peripheral blood monocytes of healthy donors, we were able to elicit melanoma-associated antigen-specific CTL in vitro. We dem onstrate the induction of CTLs directed against HLA-A2.1 presented epitopes derived from tyrosinase, gplOO, and Melan A/MÀRT-1. Apart from lysis of peptide-loaded target cells, these CTLs displayed reactivity with HLÀ-À2.1 * melanoma tumor cell lines and cultured normal mela nocytes endogenously expressing the target antigen. These data indicate that these CTLs recognize naturally processed and presented epitopes and that precursor CTLs against melanocyte differentiation antigens are pres ent in healthy individuals. The ability to generate tumor-specific CTLs in vitro, using granulocyte-macrophage colony-stimulating factor/interleukin 4-induced dendritic cells, illustrates the potential use of this type of antigen-presenting cells for vaccination protocols in human cancer