FIGURE 4.

DN STAT5a blocked the activation of the enhancer. A, Primary CD4⁺ T cells or CRL-2105 T cells were activated in the presence or absence of 100 U/ml IL-2. The data summarize three independent transient transfections of CRL-2105 T cells or primary CD4⁺ T cells using 2 mg DNA comprising the tabulated molar ratios of the indicated expression vectors to the minimal enhancer SV40 plasmids. The CMV promoter-driven expression construct DN STAT5a was constructed by mutating aa 750 of murine STAT5a into a stop codon as described (27). Transfected cells were split and cultured in the absence or presence of IL-2. Reporter expression was quantitated and corrected for the protein content of the samples. B, Primary CD4⁺ T cells or CRL-2105 T cells were transfected with DN STAT5a expression vector as indicated, followed by treatment with IL-2 and incubation with C. neoformans. The number of C. neoformans (CFU) was determined in each group as indicated. Results are expressed as mean ± SEM. Data are representative of three independent experiments. *p < 0.01 compared with the number of C. neoformans alone or resting CRL-2105 T cells incubated with C. neoformans. C, Primary CD4⁺ T cells or CRL-2105 T cells were transfected with DN STAT5a as indicated, followed by treatment with IL-2. Expression of granulysin was assessed by Western blot.