FIG. 1.

Effect of αIL-12 and CTLA4-Ig on survival and production of IFN-γ in IL-10 KO mice infected with T. gondii. IL-10 KO mice infected with T. gondii were treated i.p. with 200 μg of αIL-12 and 300 μg of CTLA4-Ig or the control antibodies (ratIgG or ChiL6) at days 5 and 7 p.i. (A) Survival of mice was monitored throughout the course of infection; (B) levels of IFN-γ in serum were determined at day 8 p.i. The data show the means ± the standard deviation (SD) of five independent experiments with n = 8 to 13 mice per group. ✽, P < 0.03; ✽✽, P < 0.001 (unpaired Mann-Whitney test). Treatment with αIL-12 resulted in a reduction in the levels of IL-12 in serum by ca. 90% at day 8 p.i. (data not shown). Mice that survived the acute phase of infection did not display increased susceptibility to infection, and at week 6 p.i. the experiments were terminated.