Reduced efficacy of chemotherapy of Plasmodium chabaudi in T cell-deprived mice.

Immunologically intact and T cell-deprived CBA mice were infected with Plasmodium chabaudi and treated with chloroquine, pyrimethamine or quinine. Chloroquine and pyrimethamine rapidly reduced the levels of parasitaemia in both types of host, but whereas the normal mice remained free of blood parasites thereafter, the deprived mice suffered recrudescences of the infection. Quinine was therapeutically more effective in the intact mice than in the deprived mice early after initiation of treatment and, while the normal mice suffered a transient recrudescence after quinine, the deprived mice retained a high parasitaemia during and after treatment. The results indicate that the immune response may contribute to effective chemotherapy of malaria.