EFFECT OF PRAZIQUANTEL AND LIPOSOME-INCORPORATED PRAZIQUANTEL ON PERITONEAL MACROPHAGE ACTIVATION IN MICE INFECTED WITH MESOCESTOIDES-CORTITETRATHYRIDIA (CESTODA)

The activation of peritoneal macrophage effector functions after thera py with free PZQ and PZQ incorporated in liposomes (lip.PZQ) was studi ed in the Mesocestoides corti-mouse model system. Each drug formulatio n was administered to an infected group of mice in 6 daily doses from day 14 p.i. Phagocytic activity of macrophages increased significantly after the administration of both drug formulations, more after lip.PZ Q with an earlier peak observed for PZQ (day 3) than for lip.PZQ (day 6). Empty liposomes had no significant effect. The average counts of i ngested particles in phagocytosing cells were significantly higher onl y after lip.PZQ administration. The pattern of changes in phagocytic a ctivity correlated with the reduction of parasite numbers in the perit oneal cavity, with the highest observed on day 6 after therapy with li p.PZQ. Phagocytosis of lip.PZQ in vivo stimulated significantly the re spiratory burst in peritoneal macrophages, with the highest concentrat ion of superoxide anions recorded on day 1 after the last dose, wherea s therapy with PZQ itself did not increase this process significantly. The capacity for the respiratory burst declined in all groups with pr ogressing infection. It is proposed that the phagocytic activity of pe ritoneal macrophages after therapy was stimulated indirectly as a cons equence of activation of the specific immune response. The larvicidal effect of lip.PZQ on the tetrathyridia in the peritoneal cavity was sy nergistic with the phagocytic activity and might be the result of doub le action of drug and superoxide anions generated during the respirato ry burst stimulated by this drug formulation.