Effects of the membrane form of SCF on mast cell histamine release induced by MBP.

CBMCs were maintained in the following conditions in the presence of soluble SCF (100 ng/mL) for 4 days before activation: (A) with conditioned medium of CBMCs and 3T3 fibroblast cocultures (■), in Transwell membranes to separate them from 3T3 fibroblasts (▪), in coculture with 3T3 fibroblasts (▨); (B) in coculture with 3T3 fibroblasts previously treated overnight with 0.1 pM SCF sense (▪) or SCF antisense (■); (C) in coculture with embryonic fibroblasts from Sl/Sl^d mutant mice (■) or with 3T3 fibroblasts (▪). Histamine release was assessed after 30 minutes of incubation with the activators at the concentrations indicated. Data are the means ± SEM of 3 experiments performed in duplicate. P < .05 compared with CBMCs cocultured with 3T3 fibroblasts (A,C) or with sense-treated cells (B).