A comparative study of the FcepsilonRI molecule on human mast cell and basophil cell lines.

ABSTRACT

BACKGROUND: Mast cells and basophils express the high-affinity IgE receptor FcepsilonRI. We have analysed the human mast cell line LAD2 and four subclones of the basophil cell line KU812 in order to reveal possible differences concerning the FcepsilonRI surface regulation, anti-IgE-triggered activation, FcepsilonRIalpha protein stability and the mRNA level of FcepsilonRIalpha-, beta- and the truncated beta-chain (beta(T)), and thereby determine the utility of these cell lines in investigations of the FcepsilonRI biology. METHODS: The surface expression of FcepsilonRI was assessed by flow cytometry, using the monoclonal antibody CRA1. The FcepsilonRI-induced cellular activation (i.e. cross-linking of FcepsilonRI) was determined by changes in the intracellular level of Ca2+, which was measured by fluorescence of Fura-2. The level of the FcepsilonRIalpha protein was determined by a Western blot technique and by a radioimmunoassay. The mRNA level of FcepsilonRIalpha, beta- and beta(T)-chain was analysed using real-time PCR. RESULTS: Two KU812 subclones and especially LAD2 had FcepsilonRI surface expression which was capable of inducing cellular activation. Both the FcepsilonRI expression and stability of the FcepsilonRIalpha protein were increased when IgE was present. All the cell lines expressed mRNA of FcepsilonRIalpha-, beta- and beta(T), with LAD2 tending to have the highest expression. However, a determination of the beta/beta(T) ratio demonstrated no difference between any of the cell clones. CONCLUSION: These cell lines are important tools in the investigation of both the FcepsilonRI molecule and the effects induced by its activation.