Figure 1. Identification of BM progenitors that lack myeloid and erythroid clonogenic potential.

(a) CD7 and CD10 expression on CD34⁺lin⁻Bone Marrow (BM) cells (representative of 7 independent experiments). Error bars represent SEM. * = p<0.050, ** = p<0.010, *** = p<0.001 (b) Myeloid and erythroid clonogenic output in methylcellulose assay of the CD34⁺lin⁻ subsets shown. (Total n=4, CD10⁻CD7⁻ and CD10⁻CD7⁺ n=2, CD10⁺ n=5) (c) Flow cytometry isolation strategy of CD34⁺lin⁻CD45RA⁺10⁺ (“CD10⁺”) and CD34⁺lin⁻CD45RA⁺CD10⁻CD62L^hi (“CD10⁻CD62L^hi ”). Over 30 independent BMs examined (see also Fig S3). (d) Myeloid and erythroid clonogenic capacity of each subset shown. All populations shown, including “total” are CD34⁺lin⁻. (p<0.001 comparing CD10⁻CD45RA⁺ and CD10⁻CD45RA⁺CD62L^hi; frequency was also significantly decreased in CD10⁻ CD62L^hi and CD10⁺ relative to all other populations shown, see Table S1a, b). IL3R^lo CD45RA⁻(“CMP”), IL3R⁻CD45RA⁻(“MEP”), and IL3R^lo CD45RA⁺ (“GMP”). (e) CD62L expression on CD34⁺lin⁻populations shown, representative of over 20 independent BMs. (f) Flow cytometry of gated CD34⁺lin⁻CD10⁻ cells showing lack of CD7 expression on CD62L^hi cells, representative of 5 independent BM. [For all phenotypes, lin⁻ is defined as negative for CD3, CD14, CD15 (aka FUT4), CD19, CD56 (aka NCAM1), and CD235a (aka GYPA)].