EFFECT OF ADAMANTYLAMIDE DIPEPTIDE ON REINFECTION RESISTANCE AFTER PRIMARY INFECTION ERADICATION IN EXPERIMENTAL SCHISTOSOMIASIS-MANSONI

The immunomodulatory effect of adamantylamide dipeptide (AdDP) was tes ted in Schistosoma mansoniinfected challenged mice and infected praziq uantel-treated (2 x 500 mg/kg) challenged animals. In AdDP-treated mic e, the drug was given 58 days post infection of mice with 120 S. manso ni cercariae, challenged with 240 cercariae one day after treatment, w hile in praziquantel treated mice, the drug was given 44 days post inf ection, two weeks post treatment (58 days post infection) they were gi ven AdDP in the same dose and one day later challenged with the same c ercarial load. AdDP increased the resistance against reinfection (90.3 % vs. 83.5% in infected challenged control). The significant increase in resistance against reinfection was accompanied by significant incre ase in the percentage of lymphocytes forming EAC rosettes. Mice cured of their primary infection by praziquantel showed a significant reduct ion in percent resistance, hepatic granuloma size and intragranulomal Thy(+) 1,2 and Lyt(+) 1 T cells. In mice treated with both praziquante l and AdDP, resistance to reinfection was significantly higher than in mice treated with praziquantel only (89.29% vs. 62.13%) reaching a le vel comparable to that recorded in infected-challenged controls. Meanw hile granuloma size was not significantly different from that in the i nfected-challenged controls with a significant rise in Lyt(+) 1 T cell s. Data may suggest a role for granuloma as a mechanical obstacle and/ or as a T cell-mediated reaction in maintenance of resistance to reinf ection. A role for B lymphocytes should be considered as the rise of p ercent resistance to reinfection in mice treated with AdDP alone was a ccompanied by a significant increase in the percentage of B lymphocyte s forming EAC rosettes. Moreover, findings may suggest the use of AdDP together with specific chemotherapy in endemic areas where reinfectio n and repeated treatment with its consequences are of common occurrenc e.