Toxoplasma

Toxoplasma gondii is a protozoan parasite capable of invading virtually every cell in the body. Individuals who are immunologically normal are relatively resistant to T. gondii in that the organism does not cause death or even severe disease in such individuals. The importance of lymphokines in inducing antitoxoplasma activity in macrophages has been known for over a decade. The results of preliminary studies performed in our laboratory suggest that the lpr gene results in exquisite susceptibility of these mice to morbidity and mortality with a strain and dose of T. gondii that has no clinically apparent effect on normal mice. The ability of T. gondii to grow and multiply within host cells has provided an excellent model for assessing the role that cell-mediated immunity plays in the development of resistance to this parasite.