Altered response of CD4+ T cell subsets to Plasmodium chabaudi chabaudi in B cell-deficient mice.

Mice depleted of B cells from birth by treatment with anti-mu antibodies can control but not clear an infection with the malaria parasite Plasmodium chabaudi chabaudi (AS). Splenic CD4+ T cells from these mice were unable to mount a significant Th2 response to the parasite in vitro as shown by much lower precursor frequencies of Th cells for antibody production and of IL-4-producing cells compared with the response of control-treated mice. CD4+ T cells of the anti-mu-treated mice which respond to antigens of P. chabaudi chabaudi maintained a Th1 phenotype throughout primary infection, in contrast to control mice in which a sequential appearance of Th1 and Th2 responses was observed. These data show that Th1 responses in anti-mu-treated mice are sufficient to control parasitemia but not to eliminate an infection. The data further suggest that depletion of B cells by treatment with anti-mu antibodies reduces the generation of the Th2 subset during a primary response to P. chabaudi chabaudi.