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Melanomas are most frequently infiltrated by actively proliferating T-lymphocytes (1). Some of these T-cells are cytolytic and recognize peptide antigens derived from melanoma-specific antigens (2). However, with the noteworthy exception of rare immune-mediated, sponaneous regressions of melanomas (3), or in the particular case of the halo nevus phenomenon in which normal melanocytes are killed by CD8(+)-specific T-cells (4), the ongoing melanocyte-specific T-cell responses are most frequently incapable of controlling the growth of the tumor, resulting in the malignant melanocytic tumors escaping an otherwise specific immune T-cell response. The understanding of the mechanisms that underlie the switch of efficient to inefficient (and vice versa) T-cell responses is thus of primary importance in conceiving specific immunotherapies of melanomas.