T(H)1 AND T(H)2 CD4(-CELL CLONES SPECIFIC FOR PLASMODIUM-CHABAUDI BUTNOT FOR AN UNRELATED ANTIGEN PROTECT AGAINST BLOOD-STAGE P-CHABAUDI INFECTION() T)

The host protective immune response to blood stage malaria infection w as 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 functio nal CD4+ cell compartment suffer unremitting patent primary parasitemi as for at least 60 days after infection. Here, we report that the adop tive transfer of eight P. chabaudi-specific CD4+ T cell clones of eith er the T(h)1 or T(h)2 type to mice rendered CD4-depleted by adult thym ectomy and anti-CD4 monoclonal antibody therapy fully restored the abi lity of recipients to control challenge infection. Control T(h)1 and T (h)2 clones specific for an unrelated antigen, ovalbumin,were unable t o confer a comparable level of protection in CD4-depleted mice, even t hough they received regular doses of the antigen. These data demonstra te that protective immunity to asexual P. chabaudi parasites can be me diated through immune CD4+ T cell clones of either the T(h)1 or the T( h)2 subset.