Immunity to Plasmodium yoelii: kinetics of the generation of T and B lymphocytes that passively transfer protective immunity against virulent challenge.

Adoptive immunization of A/Tru mice with splenic B cells or T cells from syngeneic donors with a primary, nonvirulent, Plasmodium yoelii (17X) infection confers on these recipients the capacity to resist a challenge infection with a virulent strain (YM) of P. yoelii. Unfractionated spleen cells as well as spleen cells enriched for T or B cells capable of transferring protective immunity were detected as early as Day 7 of the primary nonvirulent infection, and reached peak levels on Day 14. Spleen cells that were harvested from donor animals after resolution of the immunizing infection [on Days 21 or 28] were incapable of transferring protective immunity. The capacity of 7-day immune spleen cells to transfer immunity could be abolished by pretreatment with mitomycin C. In addition, it was found that immunocompetent recipient mice were required for successful adoptive immunization, since thymectomized, irradiated, bone marrow reconstituted mice infused with immune spleen cells failed to survive lethal challenge infections.