INHIBITION OF SPLEEN-CELL PROLIFERATIVE RESPONSE TO MITOGENS BY EXCRETORY-SECRETORY ANTIGENS OF FASCIOLA-HEPATICA

The effect of Fasciola hepatica excretory-secretory antigen (ESA) on t he proliferative response of spleen mononuclear (SpM) cells of normal rats to stimulation with mitogens has been examined, When ESA was adde d to normal SpM cells, there was a decrease in the proliferative respo nse to concanvalin A (Con A) or lipopolysaccharide (LPS) in a dose-dep endent manner, The addition of indomethacin, which blocks prostaglandi n synthesis, or N omega-nitro-L-arginine methyl eater (L-NAME) a speci fic inhibitor of nitric oxide (NO) synthase, had no effect on the abil ity of ESA to suppress the proliferative response to Con A, However, s upplementation of the culture media with catalase, which degrades hydr ogen peroxide (H2O2) or superoxide dismutase (SOD) to remove superoxid e anion (O-2(-)), resulted in a restoration of proliferation to Con A, When LPS was used as mitogenic stimulus no inhibitor added to the cul ture restored the proliferation, These results suggest that H2O2 and O -2(-) are involved in the suppressor phenomenon induced by ESA in the T-cell proliferative events. (C) 1997 Australian Society for Parasitol ogy.