MODULATION OF INTERFERON SECRETION BY CONCANAVALIN-A AND INTERLEUKIN-2 IN 1ST TRIMESTER PLACENTAL EXPLANTS IN-VITRO

The human placenta has been demonstrated to be a site of interferon (I FN) production. We report here that early human placental explants in vitro release both type I (IFN-alpha and -beta) and type II (IFN-gamma ) immunoreactive IFN. The mitogen concanavalin A (Con A) stimulated im munoreactive (ir-) IFN-gamma secretion in both a dose- and time-depend ent manner, but had no significant effect on either ir-IFN-alpha or -b eta release. The enhancement of ir-IFN-gamma secretion by Con A, at 2- 20 mug/ml, was significant at 1 h and persisted until 24 h, but was no t significant at 48 h. A high dose of recombinant human interleukin-2 (IL-2) stimulates the release of all three types of ir-IFNs, suggestin g that interaction of IL-2 with its receptor might be one cause of the constitutive production of placental IFNs. The patterns of response t o Con A and IL-2 were different from those of lymphocytes, providing i ndirect evidence suggesting that the source of these IFNs might not be lymphocytic. Taken together, these results indicate that first trimes ter human placental explants in vitro produce both type I and type II IFNs, the major IFN produced depending on the inducer. IL-2 may be one of the physiological inducers of placental IFNs.