FIG. 6.

Phosphorylation of STAT proteins in response to IFN and CD8⁺ cell fluids. Mitogen-stimulated CD4+ T cells were exposed to (A) various concentrations (0, 10, 100, and 1,000 U/mL of F12 medium) of HLI or (B) CD8⁺ cell fluids (10× concentrated using a 10-kDa filter) having relatively high and low anti-HIV activity. After 15 min of exposure, the cells were processed and stained for measurement of phosphorylated STAT1 (upper) and STAT3 (lower) by flow cytometry. Results are representative of 3 separate experiments.