The technique of blast transformation in naturally occurring disease in man, and that of macrophage migration-inhibition in experimentally induced infections in animals, were applied to the study of cellular hypersensitivity in Toxoplasma gondii and Leishmania braziliensis infections. Blast transformation of peripheral lymphocytes of patients with American cutaneous leishmaniasis occurred in the presence of leishmanin at a rate of 2% or greater, but there was no significant transformation in noninfected controls. However, in both Toxoplasma-infected patients and presumably negative controls, Toxoplasma antigens stimulated blast transformation. With macrophage inhibition, the converse relation was seen, with the more striking results obtained in the experimental Toxoplasma infections. Inhibition of macrophage migration in the presence of antigen was pronounced in five of seven guinea pigs, but only one of seven Leishmania-inoculated animals showed evidence of inhibition by leishmanin. This was correlated with development of strong skin-test reactions in the Toxoplasma animals, and only slight reactions to the Leishmania. Utilization of these in vitro immunologic techniques should be of value for further study of host response to parasitic infections.
Former Trainee in Infectious Diseases, University of Illinois College of Medicine, Visiting Scientist, MARU.
Lt. Col. MSC, USA. Chief, Parasitic Diseases Section, MARU.