Treatment with interleukin 12 in combination with atovaquone or clindamycin significantly increases survival of mice with acute toxoplasmosis.

The capacity of interleukin 12 (IL-12) to potentiate drugs in the treatment of murine toxoplasmosis was examined. IL-12 (100 ng/injection), atovaquone (10 mg/kg of body weight/day), or clindamycin (5 mg/kg/day) administered alone caused delayed time to death or minimal survival rates. In contrast, significant survival rates resulted when the same dose of IL-12 was used in combination the same doses of atovaquone (P=0.01) or clindamycin (P=0.001). Infected mice treated with IL-12 plus drug produced significantly higher levels of gamma interferon than controls. Although IL-12 was effective only when administered before infection, these results suggest that this cytokine may be a useful adjunct in the therapy of human toxoplasmosis in situations when cysts reactivate and tachyzoites start multiplying in immunocompromised patients.