Analyses of erythroid progenitors in WT and kd/kd mice. (A) Left: Flow cytometric analyses of the expression of TER119, CD71, and c-Kit in total BM cells prepared from femur of WT (top panels) and kd/kd (bottom panels) mice. Frequencies (%) of cells in gated fractions (squared) are shown. In right panels, frequencies (%) of CD71⁺/TER119⁻ (top left region) and CD71⁻/TER119⁺ (bottom right region) cells are also indicated. Right: Frequencies (%) of CD71⁺/TER119⁺ cells (gated fractions of the left panels). ■ represents WT; □ represents kd/kd. n = 3 per group; *P < .05. (B) Left: Flow cytometric analyses of the expression of TER119 and CD71 in spleen cells prepared from WT (left panel) and kd/kd (right panel) mice. Frequencies (%) of CD71⁻/TER119⁺ cells in gated fractions (squared), CD71⁺/TER119⁻ (top left region) and CD71⁺/TER119⁺ (top right region) cells are shown. Right: Frequencies (%) of CD71⁻/TER119⁺ cells (gated fractions of the left panels). ■ represents WT; □ represents kd/kd. n = 3 per group (*P < .05). (C) In vitro colony assay using BM cells from WT (■) and kd/kd (□) mice. A total of 50 000 BM mononuclear cells were plated and cultured with methylcellulose media. Note that the numbers of BFU-E– and CFU-E–derived colonies were significantly increased in kd/kd BM compared with WT (*P < .05, **P < .01). Error bars represent SD.