FIG. 4.

Effects of IFN-γ neutralization on host defense against P. carinii in γδ-TCR⁺ T-cell-deficient mice. Male B6.129P2-Tcrd^tm1Mom (Tcr-d KO) and C57BL/6 mice, 6 to 8 weeks of age, were intratracheally inoculated with 2 × 10⁵ P. carinii cysts. IFN-γ was neutralized through administration of immune rabbit serum containing antibodies against murine IFN-γ every other day for 1 week beginning 2 days postinoculation with P. carinii. Control mice received naïve rabbit serum. At specific time points, mice were sacrificed and analyzed for P. carinii lung burden and T-cell subsets. The figure illustrates representative data from three separate experiments (n = 5 to 7 animals/time point) for P. carinii burden (A) and for CD4⁺/CD3⁺ and CD8⁺/CD3⁺ BAL cell subsets (B). A single asterisk represents significant differences between control and γδ-TCR⁺ T-cell-deficient mice that received naïve rabbit serum, and double asterisks represent significant differences between γδ-TCR⁺ T-cell-deficient mice that received naïve and immune serum (P < 0.05). Data are expressed as the mean ± the standard error of the mean (A) and as values of pooled lavage samples from individual mice (B).