INVOLVEMENT OF EXCRETION SECRETION PRODUCTS FROM FASCIOLA-HEPATICA INDUCING SUPPRESSION OF THE CELLULAR IMMUNE-RESPONSES

Normal rats i.p. injected with Fasciola hepatica excretor-secretor ant igen (ESA) induced a population of spleen mononuclear (SpM) cells, whi ch suppressed the delayed type hypersensitivity (DTH) response to para site antigens as well as to non-related antigens (human serum albumin) by adoptive transfer. A similar effect was observed when the cell tra nsfer was performed with SpM cells non-adherent to nylon wool. The DTH was not modified by cells transfer adherent to nylon wool in syngenei c receptor animals. The observed suppression depended on the concentra tion and inoculation moment of the antigen; 1.8 mg of protein ESA bein g enough to suppress the DTH response at the different days studied, b efore and after immunization with whole F. hepatica antigens. A marked suppression was observed when ESA was injected on day 7 pre-immunizat ion. On the other hand, inoculation of ESA treated with 0.01 M sodium periodate (carbohydrate oxidant) diminished the suppressor effect foun d after the native ESA inoculation, indicating participation of ESA gl ucidic components in induced suppression. inoculation of ESA fractions obtained from polyacrylamide gel elution with different MW ranges, sh owed that components between 12 and 23 kDa actively induced suppressio n to the DTH response to parasite antigens.