T(H)1 AND T(H)2 CD4(+) T-CELL CLONES SPECIFIC FOR PLASMODIUM-CHABAUDI BUT NOT FOR AN UNRELATED ANTIGEN PROTECT AGAINST BLOOD-STAGE P-CHABAUDI INFECTION

The host protective immune response to blood stage malaria infection was studied using Plasmodium chabaudi chabaudi (P.chabaudi) in NIH mice. It has been shown previously that CD4+ cells are critically required for protection against erythrocytic infection. Mice lacking a functional CD4+ cell compartment suffer unremitting patent primary parasitemias for at least 60 days after infection. Here, we report that the adoptive transfer of eight P. chabaudi-specific CD4+ T cell clones of either the T(h)1 or T(h)2 type to mice rendered CD4-depleted by adult thymectomy and anti-CD4 monoclonal antibody therapy fully restored the ability of recipients to control challenge infection. Control T(h)1 and T(h)2 clones specific for an unrelated antigen, ovalbumin,were unable to confer a comparable level of protection in CD4-depleted mice, even though they received regular doses of the antigen. These data demonstrate that protective immunity to asexual P. chabaudi parasites can be mediated through immune CD4+ T cell clones of either the T(h)1 or the T(h)2 subset.