Human T lymphocyte clones with killer or natural killer activity

We describe a reliable method for obtaining a significantly higher frequency of human cloned T lymphocytes with killer and/or NK-like activity. Human peripheral blood mononuclear cells were treated with recombinant interferon-gamma (rIFN-gamma) and recombinant interleukin-2 (rIL-2) in a culture medium containing autologous serum and were then cloned by single cell micromanipulation. The cloned T lymphocyte populations were tested simultaneously for their ability to proliferate in response to exogenous IL-2, to exhibit lectin-dependent cytolysis and to kill the tumor cell line K562. Results indicate that the cloning technique allowed each isolated T lymphocyte to undergo cell expansion. Furthermore when T cells were pretreated with rIFN-gamma and rIL-2, 88% of the T cell clones were capable of mediating cytotoxicity in the presence of PHA. Moreover one third of the clones which exhibited lectin-dependent lysis were able to kill K562 target cells.