Effects of direct current on T cell activity: modulation of interleukin-2 production

The production of interleukin-2 (IL-2) by mitogen-stimulated human peripheral blood leukocytes (PBL) was significantly enhanced by a short pretreatment of PBL with direct current (DC) at low intensities. Exposure of PBL to DC of 1 mA for more than 10 min resulted in inhibition of IL-2 production which correlated with decreased proliferation capacity of the treated cells. DC had similar enhancing and inhibitory effects on IL-2 production by the mitogen-stimulated human leukemia T cell line MOLT-13. However, DC itself did not stimulate IL-2 production in PBL or in MOLT-13 cells. In two additional T cell lines tested, MOLT-16 and H-9, DC did not enhance mitogen-stimulated IL-2 production, but suppressed it when applied at 1 mA for more than 10 min. Both the mitogen-stimulated and the interleukin-1 (IL-1)-enhanced IL-2 production were completely inhibited by 1 mA of DC applied for 20 min. The observed effects of DC were due to a direct action of DC on the cells and not to possible effects of the secondary by-products of electrolysis. These results show that pretreatment of cells with DC can enhance or suppress IL-2 production depending on the intensity of DC and the type of IL-2 producing cell clones.