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-_µantibodies can control but not clear an infection with the malariaparasite Plasmodium chabaudi chabaudi (AS). Splenic CD4⁺ T cellsfrom these mice were unable to mount a significant T_h2 responseto the parasite in vitro as shown by much lower precursor frequenciesof T_h cells for antibody production and of IL-4-producing cellscompared with the response of control-treated mice. CD4⁺ T cellsof the anti-_µ-treated mice which respond to antigens ofP. chabaudi chabaudi maintained a T_h1 phenotype throughout primaryinfection, in contrast to control mice in which a sequentialappearance of T_h1 and T_h2 responses was observed. These datashow that T_h1 responses in anti-_µ-treated mice are sufficientto control parasitemia but not to eliminate an infection. Thedata further suggest that depletion of B cells by treatmentwith anti-_µ; antibodies reduces the generation of theT_h2 subset during a primary response to P. chabaudi chabaudi.