L3T4+ T lymphocytes play a major role in the pathogenesis of murine cerebral malaria.

The pathogenic importance of L3T4+ T cells in the development of murine cerebral malaria was demonstrated by the following observations. First, in vivo administration of an anti-L3T4 monoclonal antibody protected Plasmodium berghei-infected CBA mice from the development of neurologic symptoms and acute death. In contrast, injection with an MAb directed against the Ly.2+ T cell subset had no protective effect. Second, thymectomized, irradiated, and bone marrow reconstituted (ATxBM) CBA mice did not develop acute cerebral malaria when infected by P. berghei, although parasitemia and anemia rose to the same extent as in normal P. berghei-infected CBA mice. The occurrence of lethal neurologic perturbations could be restored in ATxBM mice selectively reconstituted with L3T4+ Ly.2-lymphocytes but not with Ly.2+ L3T4- cells. Third, adoptive transfer of L3T4+ cells from mice dying of cerebral malaria into euthymic mice subsequently infected by P. berghei led to an acceleration of the disease. These results confirm that cerebral malaria in mice is the expression of immunopathologic reactions and outline the particular pathogenic importance of L3T4+ T cells.