Heterogeneity of lymphokine-activated killer cells: Role of interleukin-2 and interleukin-4.

Abstract

Our main objective was to determine if the Lymphokine Activated Killer cells (LAK) activity is restricted to Natural Killer (NK) cells or if it is also detectable in T cell subsets, especially in CD3+ T cells that are also negative for CD4 and CD8 cell surface markers. We were able to obtain highly purified subsets of NK cells, helper/inducer (CD3+4+8$-$), suppressor/cytotoxic (CD3+4$-$8+) and double negative (CD3+4$-$8$-$) T cells. The double negative T cells are now known to be a subset of $\gamma\delta$-T cells. Highly purified subsets were obtained using antibody (sheep anti-mouse IgG) coated magnetic particles and monoclonal antibodies. The purified subsets were tested for LAK activity against a standard target cell (K562), a NK resistant/LAK sensitive target cell (HTB 38), and a NK/LAK resistant target cell. We found NK cells develop LAK activity after IL-2 stimulation and that two T cell subsets (cytotoxic/suppressor and double negative) consistently showed LAK activity (3 experiments). The helper/inducer subset showed LAK activity in 2 of 3 experiments. Interleukin 4 had an inhibitory effect on the proliferative activity of IL-2 stimulated T cells and was not used in the LAK experiments. In conclusion we have found that the LAK function is a property of an heterogeneous group of lymphocyte subsets that includes NK cells and T cell subsets. (Abstract shortened by UMI.)