Oligoclonality was investigated in interleukin-2 (IL-2)-activated T cells (tumor-infdtrating lymphocytes, TILs) residing in metastatic melanomas using seven different monoclonal antibodies (mAbs) specific for T-cell receptor (TCR) Va or V~ regions and flow cytometry. IL-2-activated TILs from 25 of 42 metastatic melanomas (60%) displayed oligoclonal expansion, whereas IL-2-activated peripheral bllod mononuclear cells (PBMCs) from only 2 of 20 patients (10%) did so during 2-5 weeks in culture. Skin-derived lymphocytes from 20 patients were cultured; only four samples proliferated and none showed oligoclonal expansion. Preferential oligoclonal expansion of TILs was observed in V~8 + cells (10/42, P < 0.05), V/16.7 + cells (7/42, P < 0.05), and Va2 + cells (7/42, not significant). Oligoclonal expansion of V/]8 + cells was primarily found in T cells from subcutaneous metastases (8/20 cases, P < 0.05), whereas that of V/16.7 + cells and Va2 + cells was also found in T cells from lymph node or organ metastases. These mAbs to TCR V regions stimulated effector TILs to produce interferon-y, but not IL-2 or IL-4. Subcutaneous tumor-specific (Vi~18 + cells) and non-specific (V//6.7 + cells and Va2 + cells) oligoclonalities were observed in IL-2-activated melanoma T|Ls, suggesting different immune responses among different sites of metastases.