Effect of Egr-1 on macrophage/granulocyte differentiation of myeloid-enriched BM cells.

Uninfected BM cells (BM control), BM cells infected with MSCVneo (BMneo), and BM cells infected with MSCVneo Egr-1 (BMEgr-1) were seeded in methylcellulose supplemented with the indicated cytokines with or without G418, at the same concentrations indicated in the legend for Figure 1. To determine different cell types, colonies generated after 8 days were isolated, pooled, and used for cytospin smears. At least 300 May-Grünwald–stained cells were scored for each sample. (A) Percentage (± SD) of cell types in 3 independent determinations.P values (Student t test) for the difference in the percentage of granulocytes (Gra) or macrophages (Mac) of BMneo compared with BMEgr-1 cells were IL-3/Gra, P < .001; IL-3/Mac, P < .01; SCM/Gra, P < .05; SCM/Mac, P < .05; G-CSF/Gra, P < .001; G-CSF/Mac, P > .05 (not significant); GM-CSF/Gra,P > .05 (not significant); GM-CSF/Mac,P < .05; M-CSF/Gra, P > .05 (not significant); and M-CSF/Mac, P < .05. (B) Representative photomicrographs of May-Grünwald–stained cytospin smears of BM cells obtained from 8-day methylcellulose colonies plus IL-3 (with G418) that were generated by BM cells infected with either MSCVneo (BMneo) or MSCVneo Egr-1 (BMEgr-1).