T_H2 cytokine-mediated comitogenesis and phenotypic analysis. (A) hMCs developed for 3 weeks in the presence of SCF, IL-6, and IL-10 in serum-free medium containing 5 μM LPA were washed into new medium containing SCF and the indicated additives. [³H]-Thymidine incorporation (top) was measured after 3 days. Results are the mean ± half-range from 2 experiments and are expressed as a percentage increase over the baseline of SCF alone. Cell numbers (bottom) relative to SCF alone at 3 days from the same 2 experiments are displayed. (B) Cytofluorographic analysis for Kit at day 3 of comitogenic stimulation. Data are from 1 of 2 representative experiments. Histograms depict cell-surface kit expression (unshaded tracings) and negative control antibody (shaded tracings). Percentages of Kit-positive cells from this experiment are noted above each corresponding histogram.