Effects of interleukin 4 upon human tumoricidal cells obtained from patients bearing solid tumors

The use of human interleukin 4 (IL4) in the generation of tumoricidal effector cells derived from cancer patients undergoing either interleukin 2/lymphokine activated killer cells (IL2/LAK) therapy or tumor derived activated cell (TDAC) therapy was examined in the present study. Human IL4 alone did not generate LAK cells from patients undergoing IL2/LAK therapy when cultured in media containing 2% AB serum (five out of six patients). However, when the serum free medium, Aim V, was used, IL4 did generate LAK cells (eight out of nine patients), although not as cytotoxic as those activated with IL2. When cells were cultured in both IL2 and IL4 during the generation of LAK cells (3-7 days), better cell recoveries were frequently observed. The cytolytic activity of these cells against Daudi target cells was slightly reduced when compared to that response induced by IL2. This inhibition of LAK activity by IL4 was dose dependent with 1,000 U/ml IL4 producing maximal effects. This form of inhibition did not correlate with any phenotypic differences between those cells cultured in IL2 and those cells cultured in IL2 plus IL4. The IL4 mediated inhibition was also observed when the cells were cultured in Aim V medium which contains indomethacin. This inhibition induced by IL4 could not be overcome by using supra-optimal IL2. In addition to its effect during the generation of IL2 induced LAK cells, IL4 also appeared to reduce the cytolytic activity of pre-activated mature LAK cells. These results suggest that IL4 has a complex role in regulating the actions of LAK cells induced by lymphokines. When IL4 was used with IL2 during the first 5 weeks of growth of TDAC, an enhanced growth was observed when compared to the growth of TDAC when only one lymphokine was used. Besides the growth enhancement of TDAC, a better cytolytic response was observed when both lymphokines were used together. Thus, for the best growth of TDAC both IL2 and IL4 are required.