T Cell Receptor‐independent Cell‐mediated Cytotoxicity by Nude Mouse Lymphokine‐activated Killer Cells

Lymphokine‐activated killer (LAK) cells, which can lyse a variety of tumor cells, can be induced from both normal and athymic nude mouse spleen cells by culture with high doses of recombinant interleukin 2 (rIL‐2). LAK cells generated from nude mouse spleen cells (Nude‐LAK cells) express just Thy 1.2 antigen, but not CD4 and CDS antigens. Nude‐LAK cells express neither T3 molecule, T cell receptor (TCR) αβ nor TCR γδ on their cell surface. The lack of TCR expression on Nude‐LAK cells was confirmed by the results of northern blot analysis. LAK cells generated from normal mouse spleen cells (Nor‐LAK) express TCR α, β transcripts, while Nude‐LAK cells express only sterile TCR β transcript, but not TCR α transcript. TCR γδ transcripts were scarcely detected in both Nor‐LAK cells and Nude‐LAK cells. Thus, it is strongly suggested that Nude‐LAK cells can recognize and lyse tumor cells by TCR‐independent mechanisms. Monoclonal antibody against lymphocyte function‐associated antigen (LFA‐1) molecule can block the Cytotoxicity of Nude‐LAK cells, indicating an important role of such accessory molecules in Nude‐LAK cell‐mediated Cytotoxicity.