Further characterization of Fc gamma RII and Fc gamma RIII expression by cultured human mast cells

Background: We have reported that resting human mast cells exhibit minimal expression for Fc gamma RI, a nd that interferon-gamma will upregulate this expression. The expression of Fc gamma RII and Fc gamma RIII by human mast cells remains to be fully examined. Methods: To investigate Fc gamma RII and Fc gamma RIII expression, we determined mRNA and protein expression of Fc gamma RII and Fc gamma RIII in human peripheral blood CD34+ derived cultured mast cells by RT-PCR and flow cytometry. The expression of Fc gamma RII and Fc gamma RIII in intact and permeabilized mast cells was also compared. We measured histamine release to monitor mast cell degranulation following cross-linking of Fc gamma RII. Results: We found by RT-PCR that resting human mast cells exhibit mRNA for Fc gamma RIIA, Fc gamma RIIb1, Fc gamma RIIb2 and Fc gamma RIII but not Fc gamma RIIC. FAGS analysis of Fc gamma receptors in intact versus permeabilized mast cells showed expression of Fc gamma RII to be 42.2 +/- 3.9% and this was unchanged by permeabilization. Fc gamma RIII protein expression was minimal and this was also unchanged by permeabilization. Aggregation of Fc gamma RII on human mast cells led to no significant degranulation as evidenced by histamine release. Conclusions: In addition to Fc gamma RI expression, human mast cells express Fc gamma RIIA, Fc gamma RIIb1, Fc gamma RIIb2 and Fc gamma RIII mRNA, and significant surface expression of Fc gamma RII. Aggregation of Fc gamma RII on cultured human mast cells in this model was not followed by histamine release. Copyright (C) 2001 S. Karger AG, Basel.