[Roles of T cell subsets in the protective immunity of mice against Plasmodium yoelii]

BALB/c mice which had developed protective immunity against Plasmodium yoelii (P. y.) challenge were injected with anti-CD4 or anti-CD8 monoclonal antibody, and were then challenged again with P. yoelli. No impairment of protection was observed. CD8+T cells obtained from spleens of these mice were transferred to BALB/c nude mice and induced partial protection, while transfer of CD4+T cells did not so. In P. yoelli-mouse model, the parasites invaded reticulocytes in the early infection, and the infected reticulocytes could be recognized and attacked by sensitized CD8+T cells. In late infection when P. yoelli also invaded mature erythrocytes, the protective effect of CD8+T cells decreased and the main role of protection was played by antibodies.