Trypanosoma rhodesiense infection in B-cell-deficient mice.

B-cell-deficient C57B1/6J mice (suppressed from birth with goat anti-mu) and controls (treated from birth with normal goat serum) were infected with Trypanosoma rhodesiense. There was a significant (P less than 0.01) decrease in duration of survival of the mu-suppressed mice compared with that of controls. Whereas both mu-suppressed and control mice had an initial rise in parasitemia of similar magnitude, only the control mice exhibited a subsequent period during which the parasitemia fell to undetectable levels. In control mice, immunization with irradiated organisms prevented the development of detectable parasitemia after challenge with viable trypanosomes. However, immunization did not alter the course of infection in B-cell-deficient mice. These results indicate that immunity to T. rhodesiense infection in mice is dependent on B-cell immunocompetence.