Accelerated differentiation of RARα^−/− granulocytes in liquid cultures stimulated with G-CSF and SCF.

Cultures of CFSE-labeled BM cells were harvested 3 days after their initiation and stained for Mac-1 and GR-1 expression. The RAR antagonist BMS493 or the RXR/RAR agonist 9C-RA was added at the onset of the culture at a final concentration of 10⁻⁶ M, where indicated. (A) The analysis was limited to CFSE^low cells, which correspond to cells that have arisen during the culture from proliferation of immature granulocytes. Note that CFSE^highcells correspond exclusively to mature granulocytes with a Mac-1^highGR-1^high phenotype (data not shown). (B) Representative GR-1/Mac-1 profiles of CFSE^low cells. Note the shift toward the more immature phenotype in the BMS493-treated WT sample and the similarity of the phenotypes of all RARα^−/− samples with that of the 9C-RA–treated WT sample. (C) Quantification in percent of all cells present in gates B and C of immature (gate B in panel A) and mature (gate C in panel A) cells from the experiment displayed in panel B. The experiment described in this figure was performed in duplicate for each of the 2 WT and 2 RARα^−/− mice. For a given set of culture conditions and mouse genotype, variations in the percentage of the gated populations were within 1.5% of those indicated.