Fresh (uncultured) TIL from 12 untreated patients with primary renal cell carcinoma were prepared from tumour specimens by enzymatic digestion, and were characterized by immunofluorescence using MoAbs recognizing leucocyte differentiation antigens or particular V alpha or V beta segments of the T cell receptor (TCR). These fresh TIL comprised CD3+ (20-84%); CD4+ (3-15%); CD8+ (13-35%); alpha beta TCR+ (20-50%); gamma delta TCR+ (3-17%); CD16+ (1-18%) and CD56+ (3-10%) cells. Significant proportions of V alpha 2+, V beta 5.1+ and V beta 6+ cells were found in TIL of certain patients with renal cell carcinoma, suggesting that they comprised oligoclonal T cells. T cell lines were developed in low concentrations of rIL-2 (200 U/ml) from TIL from 11 patients with renal cell carcinoma, and were characterized by immunofluorescence and cell-mediated cytotoxicity. These T cell lines consisted primarily of CD3+ (51-94%); CD4+ (1-80%); CD8+ (0-84%); alpha beta TCR+ (65-87%); gamma delta TCR+ (0-25%); CD16+ (0-16%) and CD56+ (2-57%) cells. These T cell lines exhibited non-specific cytotoxicity against autologous and allogeneic renal tumour cells, with the exception of one T cell line that exhibited preferential cytotoxicity against autologous renal tumour cells. These results suggest that fresh TIL from patients with renal cell carcinoma contain significant proportions of oligoclonal T cells that may have accumulated at the tumour site as a result of a clonal expansion.