The immunomodulatory effect of
adamantylamide dipeptide (AdDP) was tested in Schistosoma mansoni-infected challenged mice and infected
praziquantel-treated (2 x 500 mg/kg) challenged animals. In AdDP-treated mice, the
drug was given 58 days post
infection of mice with 120 S. mansoni cercariae, challenged with 240 cercariae one day
after treatment, while in
praziquantel-treated mice, the
drug was given 44 days post
infection, two weeks post treatment (58 days post
infection) they were given AdDP in the same dose and one day later challenged with the same cercarial 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 increase in the percentage of lymphocytes forming EAC rosettes. Mice cured of their primary
infection by
praziquantel showed a significant reduction in percent resistance, hepatic
granuloma size and intragranulomal Thy+ 1,2 and Lyt+ 1 T cells. In mice treated with both
praziquantel and AdDP, resistance to
reinfection was significantly higher than in mice treated with
praziquantel only (89.29% vs. 62.13%) reaching a level comparable to that recorded in infected-challenged controls. Meanwhile
granuloma size was not significantly different from that in the infected-challenged controls with a significant rise in Lyt+ 1 T cells. Data may suggest a role for
granuloma as a mechanical obstacle and/or as a T cell-mediated reaction in maintenance of resistance to
reinfection. A role for B lymphocytes should be considered as the rise of percent resistance to
reinfection in mice treated with AdDP alone was accompanied by a significant increase in the percentage of B lymphocytes forming EAC rosettes. Moreover, findings may suggest the use of AdDP together with specific
chemotherapy in endemic areas where
reinfection and repeated treatment with its consequences are of common occurrence.