In vivo infiltration of mononuclear cells in squamous cell carcinoma of the head and neck correlates with the ability to expand tumour-infiltrating T cells in vitro and with the expression of MHC class I antigens on tumour cells.

A series of 18 head and neck squamous cell carcinoma biopsies, 6 primary and 12 recurrent, were investigated for tumour-infiltrating mononuclear cells with monoclonal or polyclonal antibodies. Our results suggest that the number of T cells at the tumour edge in vivo correlates well with their ability to expand in vitro in the presence of high-dose interleukin-2 (2000 U/ml). High MHC class I antigen expression on tumour cells was found to be positively correlated with p53 overexpression, suggesting that p53-derived peptides, wild-type or mutated ones, presented by MHC class I antigens, are potential targets for MHC-restricted cytotoxic T cells in head and neck squamous cell carcinomas. However, lack of correlation between peritumoural T cell infiltration in vivo and T cell expansion in vitro, on the one hand, and p53 overexpression on tumour cells, on the other hand, suggests absence of p53-peptide-specific T cells in the patients. Eight out of ten expanded tumour-infiltrating lymphocyte (TIL) cultures showed T-cell-mediated cytotoxicity. "Promiscuous" cytotoxic T cell activity against the natural-killer-cell-sensitive K562 target cell line was observed in three out of ten TIL expansion cultures.