Generation of Antimelanoma Cytotoxic T Lymphocytes from Healthy Donors after Presentation of Melanoma-associated Antigen-derived Epitopes by Dendritic Cells in Vitro1

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 entiation 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.