Effects of TPO and G-CSF on viability of normal human neutrophils maintained in culture.

(A) Neutrophils were maintained in culture at 37°C with and without recombinant human TPO (10 ng/mL) or recombinant human G-CSF (10 ng/mL) as designated above. At 0, 24, and 48 hours, cell viability was determined by an Alamar Blue–based assay as described in “Materials and methods.” Data are reported as the mean ± SEM of 5 separate experiments performed with neutrophils isolated from independent healthy donors. *A statistically significant difference in viability as compared with control cells maintained in culture for the time period indicated (P < .05). (B) Two additional experiments were performed using all combinations of TPO plus G-CSF. Attempts to demonstrate synergy between TPO and G-CSF were performed at a midoptimal dose of the latter (1 ng/mL).