Changes in cellular immunity of mice treated for larval toxocarosis with fenbendazole

The proliferative response of splenic T and B lymphocytes, percentage of CD 4+ and CD8+ T cell subpopulations and production of the peritoneal macropha ge superoxide anion (O-2(-)) were studied in healthy and Toxocara canis inf ected mice after anthelmintic treatment with fenbendazole. The drug was administered at a dose of 10 mg/kg b. w. twice a day for 5 day s. Fenbendazole given to healthy (uninfected) mice stimulated the prolifera tive response of T and B cells to nonspecific polyclonal activators (ConA, LPS), however, partially inhibited the percentage of CD4+ and CD8+ T lympho cytes. Production of O-2(-) increased only insignificantly. Infection of mi ce primarily inhanced the percentage of CD4+ T lymphocytes, compared with C D8+ cells. The treatment of infected mice considerably stimulated the proli ferative response of B cells in comparison with T cells. The percentage of CD4+ T cells in spleen was moderately reduced after treatment while that of CD8+ increased significantly. Fenbendazole considerably activated the prod uction of the peritoneal macrophage superoxide anion O-2(-) by day 24 after its last administration. The efficacy of the anthelmintic on the reduction of the migrating larvae count was 30.3 % in the muscles and 26 % in the br ain.