Melanoma cells are considered to be immunogenic because they express melanoma-associated antigens that are recognized by autologous T-cells. The role of T-lymphocytes in the host's immune response to cancer in general and to melanoma in particular has been studied intensively during the past decade, and an immense amount of data have strengthened the notion that a functional and specific antimelanoma T-cell response operates in melanoma patients (1,2). This assumption has been strongly reinforced by the demonstration of clonotypic T-cells in both primary and metastatic melanoma (3,4). Nevertheless, the prognosis of metastatic melanoma is one of the most unfavorable in medicine. The coexistence of tumor-specific immunity with a progressing tumor remains a major paradox of tumor immunology and highlights the urgency to reveal new insights into the biology of antitumor T-cells.