The effect of reticulocytosis on Plasmodium vinckei infection in white mice. Action of phenylhydrazine and of repeated bleedings

Phenylhydrazine-HCl in a single dose of 0.06 mg/g protects mice against a virulent strain of P. vinckei. This drug does not seem to have any immediate effect on the parasite and would act mainly by inducing reticulocytosis. Bleeding-induced reticulocytosis affords the same degree of protection as with haemolytic drugs, thus confirming the role of reticulocytosis.Quantitative data show that the parasite cannot achieve full development in an immature red cell. Surviving mice display a strong immunologic protection against subsequent P. vinckei infection.