FIG 2.

Effect of JAK inhibitors on proliferation and viability of primary human lymphocytes stimulated with PHA or PHA plus IL-2 (A and C). For PHA-stimulated lymphocytes, viability and proliferation were not significantly different from those of cells exposed to medium alone for all concentrations of either ruxolitinib or tofacitinib (B). For lymphocytes stimulated with PHA plus IL-2, viability was not significantly different from that of cells exposed to medium alone for all concentrations of either ruxolitinib (dotted line with squares) or tofacitinib (light gray line with diamonds) (D). However, proliferation was significantly inhibited by 1 μM ruxolitinib or tofacitinib. For all experiments, cells were incubated with medium alone or drug-containing medium for 5 days prior to assessment of cell count and viability. The cycloheximide positive control (solid line, diamonds) was toxic in a dose-dependent manner, as expected. Data are means and standard deviations for at least three independent experiments conducted with at least four pooled donors and duplicates within each experiment. Dotted bars represent mean cell counts or viability for cells maintained in drug-free medium.