[Infection of the athymic rat by Toxoplasma gondii]

In contrast to normal rats which are resistant to T. gondii infection (10(7) tachyzoïtes), athymic rats did not survive an intraperitoneal infection with 10(3) toxoplasma. When nude rats were injected intravenously with lymph node cells from hirsute littermates, they became resistant in a dose-dependent manner to the infection. In addition, reconstituted athymic rats having survived for more than 4 months the first infection were also protected against a second challenge with 10(5) tachyzoïtes. Anti-T. gondii antibody levels detected in reconstituted athymic rats were related to protection. These preliminary findings suggest that T-dependent immunity is essential in the development of effector mechanisms involving antibodies in resistance to toxoplasmosis.