Effect of IFN-γ on day 7 ECFCs.

(A) Day 7 ECFCs were cultured with or without rhEPO (10 U/mL) and/or rhIFN-γ (1000 U/mL) for the indicated time. Viability of the cells was determined by trypan blue exclusion. Each point indicates the mean ± SD of triplicates. (B) Erythroid colony-forming capacity after liquid culture for 16 hours with or without rhEPO (10 U/mL) or rhIFN-γ (1000 U/mL), or both, was determined by plasma clot assay. (C) Colony-forming capacity of day 7 ECFCs. Cells were cultured in plasma clots, in the presence or absence of rhEPO (10 U/mL) or rhIFN-γ (1000 U/mL), or both. Large erythroid colonies include more than 20 hemoglobinized cells per colony; medium erythroid colonies include 8 to 19 cells per colony; and small erythroid clusters include 2 to 7 hemoglobinized cells per aggregate, (B) and (C). Each point indicates the mean of triplicate studies.