Cell surface expression of FcεRI α chain.

The histograms represent 12-week-old PB-derived MCs (A, B, C), 12-week-old CB-derived MCs (D, E, F), and 22-week-old CB-derived MCs of the same batch with the 12-week-old MCs (G, H, I). These MCs were treated with SCF + IL-6–supplemented medium alone (A, D, G), IgE (B, E, H), and IgE + IL-4 (C, F, I) for 48 hours. CB-derived MCs at more than 20 weeks of culture showed significantly smaller levels of FcεRI α chain when compared with PB-derived MCs (MFI ratios, 1.00 ± 0.00, 1.22 ± 0.05, and 1.97 ± 0.09 when they were untreated, treated with IgE, and treated with IgE + IL-4, respectively; n = 3; Table 3).