FIG. 2.

fl-hKITL, tr-hKITL, and mKITL are equally potent in sustaining MK and EB expansion from CB CD34^pos cells in cultures not supplemented with DXM. (A) Growth curves of CB CD34^pos cells cultured for up to 14 days in the presence of IL-3 and TPO alone (no KITL, blue) or with either fl-hKITL (black), tr-hKITL (red), or mKITL (green) (50 ng/mL in all cases), as indicated. Data are expressed as FI with respect to the numbers of CD34^pos cells seeded at day 0. (B) FACS profile for CD41a and CD42b expression (on the left) and morphology (by May-Grunwald staining, on the right) of cells obtained after 12 days in cultures. Arrowheads indicate representative MKs. Magnification 40×. (C) Frequency of MK and non-MK populations (mostly EBs) in the flow cytometric analysis shown in (B). MK, megakaryocytic; EBs, erythroid precursors; DXM, dexamethasone; IL, interleukin; FI, fold increase.