Studies of the responses of basophil and eosinophil leucocytes and mast cells to the nematode Trichostrongylus colubriformis. II. Changes in cell numbers following infection of thymectomised and adoptively or passively immunised guinea-pigs.

The role of the immune response in the generation of the basophilia and eosinophilia found during expulsion of the intestinal nematode parasite, Trichostrongylus colubriformis, by guinea-pigs was investigated by studying cell numbers in animals whose immune responsiveness had been modified by thymectomy and adoptive or passive immunisation. Basophilia, but not eosinophilia, was depressed in thymectomised guinea-pigs. Bone marrow basophil numbers were significantly increased in T. colubriformis-infected guinea-pigs following the infection of mesenteric lymph-node cells from both normal and T. colubriformis-immune syngeneic donors. Bone marrow basophil counts were also increased following the injection of immune lymph-node cells into uninfected recipients. Small intestine eosinophil numbers in adoptively immunised guinea-pigs showed a pronounced increase following infection with T. colubriformis. A smaller increase followed infection of passively immunised guinea-pigs. These results, and other work with this system, suggest that basophilia and eosinophilia during T. colubriformis infection, although associated with the immune response, might not be fully explained as direct consequences of the interaction of parasitic antigens and sensitised lymphocytes or antibodies.