Interleukin-2 activated human killer lymphocytes: lack of involvement of interferon in the development of IL-2-activated killer lymphocytes.

When cultured with native or recombinant interleukin-2 (IL-2) human small agranular lymphocytes acquire the ability to kill various tumor targets. The development of these IL-2 activated killer (IAK) cells, also known as LAK, is observed in the absence of antigen or mitogen. Interferons are known to augment the lytic effects of natural killer cells and cytolytic T lymphocytes. Our study was undertaken to examine the effect of human alpha, beta, and gamma interferons on the induction and the effector phase of IAK function. When cultured with small lymphoid cells IFN alone did not induce anti-tumor cytolytic activity in those lymphocytes. Despite their known anti-proliferative effects, none of the 3 IFN species at any concentrations tested inhibited the development of IAK activity when present during the entire culture period. IFN neither inhibited nor augmented the development of IAK cells under suboptimal conditions. Furthermore, activation of IAK cells was not affected by the presence of neutralizing antibodies to either alpha or gamma IFN. Post-activation exposure of IAK cells to IFN also failed to either augment or inhibit their lytic activity. Thus, neither endogenously generated nor exogenously added IFN had any effect on the IAK system, in contrast to their augmenting effects on NK cells and CTL.