Tumor infiltrating lymphocytes in melanoma comprise high numbers of T-cellclonotypes that are lost during in vitro culture

Melanoma is generally accepted as being an antigenic tumor capable of elici ting T-cell responses that, however, in most cases are inadequate to contro l tumor growth. Tumor-infiltrating lymphocytes (TIL) in melanoma lesions co mprise clonotypic T cells, indicating the in situ recognition of melanoma-a ssociated peptide epitopes. Cultured TIL have been studied in order to unve il characteristics of TIL and the interactions of TIL and melanoma cells. W hether in vitro cultured TIL mirrors the in, situ situation has, however, b een questioned. In the present study we have taken advantage of T-cell rece ptor clonotype mapping methodology to conduct a full and detailed analysis of the T-cell clonotypes in melanoma lesions and in corresponding lines of TIL established in vitro. All melanoma lesions and the corresponding TIL cu ltures comprised high numbers of T-cell clonotypes, typically in the range of 40 to more than 60. The subsequent comparison of T-cell clonotypes prese nt in the original lesions and in the corresponding T-cell lines establishe d in vitro demonstrated that a very limited number of the T-cell clonotypes established in vitro are identical to the T-cell clonotypes expanded in si tu. These results demonstrate that in situ T-cell clonotypes in melanoma ar e not readily expanded in vitro and that the majority of T-cell clonotypes present in cultured TIL are not present in situ. (C) 2000 Academic Press.