FENBENDAZOLE AND ITS EFFECT ON THE IMMUNE-SYSTEM OF THE SHEEP

Ten parasite-free 6-month-old lambs were drenched on days 0 and 28 wit h fenbendazole and 1 day after each drench were injected with human er ythrocytes and ovalbumin. Ten other lambs injected with the antigens w ere not drenched with anthelmintic and served as controls. Lymphocytes from the fenbendazole-drenched lambs collected 3 days after the first antigen injections and cultured in vitro in RPMI 1640 plus 5% foetal calf serum, and lymphocytes collected at 3 and 7 days and cultured in RPMI plus 50% autologous serum, had decreased blastogenic activity com pared with lymphocytes from control lambs. Similiarly, decreased blsto genesis was observed with lymphocytes collected 7 days after the secon d antigen injections from drenched lambs and cultured in 50% autologou s serum containing concanavalin A. In contrast, increased blastogenesi s was seen with lymphocytes collected 14 days after the second antigen injections from the drenched lambs and cultured in 50% autologous ser um containing phytohaemagglutinin. Similar antibody responses were see n for the drenched and control lambs in response to the injections of both antigens except that, after the second injection, there was a sig nificant reduction in antibody response to human erythrocytes in the f enbendazole-treated lambs. Decreased serum complement levels were seen particularly 3 and 7 days after the second antigen injections in dren ched lambs. These serum samples had increased conglutinin activity. At the end of the experiment, the fenbendazole-drenched lambs were signi ficantly heavier than the control lambs. However, this did not appear to be related to any effects of fenbendazole on levels of growth promo ting hormones.