The stimulation of EL-4 cells to produce interleukin-2 and its potential use in immunocytotoxicity testing

The ability of EL-4 thymoma cells to produce interleukin-2 (IL-2) following exposure to phorbol-12-myristate 13-acetate (PMA) and Concanavalin A (Con A) has been studied in vitro using medium containing either 10% or 1% fetal calf serum (FCS). The potent stimulatory effect of PMA on IL-2 production by EL-4 cells has been confirmed by measuring 3H-thymidine incorporation by the IL-2-dependent T cell line, CTLL-2, in the presence of conditioned medium (CM) from stimulated cultures. EL-4 cells produced several times more IL-2 when cultured in medium containing 10% FCS than when only 1% FCS was present. Added together, PMA and Con A acted synergistically in some EL-4 cell cultures. The ability of E:-4 cells to produce IL-2 was maintained after further incubation without stimulants. CM with IL-2 activity from stimulated EL-4 cells could prove useful in immunotoxicity testing.