Expression of Fcγ receptors in human intestinal mast cells. (A) PCR detecting mRNAs encoding for GAPDH, FcγRI, FcγRIIa, FcγRIIb, FcγRIIc, and FcγRIII. For FcγRIIb the two isoforms FcγRIIb1 (343 bp) and FcγRIIb2 (289 bp) were detected. Lane 1: PBMCs (positive control). Lane 2: intestinal MCs cultured in the presence of SCF (50 ng/ml). Lane 3: intestinal MCs from the same donors cultured in the presence of SCF and IFN-γ (100 ng/ml) for the last 3 days. One experiment out of 10 is shown. FcγRIIb expression was found in MCs derived from 4 out of 10 donors (data not shown). (B) Surface expression of FcγRI (CD64), FcγRII (CD32), and FcγRIII (CD16) following culture of MC in the presence of SCF with or without the addition of IFN-γ (100 ng/ml) for the last 3 days. One experiment out of three is shown.