66This chapter is principally concerned with cell-mediated immunity (CMI) in the sense of nonantibody effector mechanisms and their modification by T cells and T cell products. Our interest in this topic began some 12 years ago when we found that, in a murine blood-stage malaria model, protection by vaccination correlated better with various cell-mediated changes than with antibody levels. 1 We subsequently showed that parasites could be killed in several ways by myeloid cells and their products, some of which could be enhanced by vaccination; this work is reviewed in Section IV.