Study of some immunopharmacological properties of praziquantel in experimental schistosomiasis mansoni

The immunopharmacological properties of praziquantel were studied in mice infected with Schistosoma mansoni. Hepatic granuloma measurement was the main parameter of assessment. Delayed foot pad swelling as an in vivo correlate for the delayed granulomatous hypersensitivity reaction was also determined. Fluorescent direct antigen-antibody reaction in the granuloma together with the immediate foot pad swelling were used to test for the humoral immune response. Praziquantel administered at seven weeks after infection in two dose regimens (3 x 250 mg kg-1 for three consecutive days and 3 x 83 mg kg-1 given four hourly within the same day was more or less equally effective in reducing the size of hepatic granuloma by 37-41% two weeks after treatment and by 81-85% one month after treatment. Delayed foot pad swelling using soluble egg antigen (SEA) was significantly suppressed one month after treatment by 53%. At nine weeks after infection the fluorescent antigen-antibody reaction in the granuloma was positive in the untreated controls, but at the same time (i.e. two weeks after treatment) it was negative in the praziquantel-treated mice. One month after treatment positivity was less compared to infected control mice. Reduction in worm burden, hepatic shift of the worms and the reduced number of ova per gram of tissue denoted the efficacy of the drug in its two dose regions against the Egyptian strain of S. mansoni.