Human conjunctival mast cells - Expression of Fc epsilon RI, c-kit, ICAM-1, and IgE

Objective: To characterize the expression and regulation of conjunctival ma st cell surface receptors important in allergic inflammation. Methods: Mast cells were isolated from human conjunctival tissues of cadave rs. Mast cell surface markers were identified using flow cytometry with ant ibodies to IgE, Fc epsilon RI, c-hit, and intercellular adhesion molecule-1 (ICAM-1). We evaluated the effect of 24-hour tumor necrosis factor alpha ( TNF-alpha) or interleukin 4 (IL-4) incubation on the expression of mast cel l c-hit, ICAM-1, and surface-bound IgE. Results: Staining of mast cells (c-kit and/or tryptase positive) yielded po sitive results for all of the variables measured. The intensity of mast cel l c-hit staining increased with TNF-alpha incubation, but decreased below t hat of unstimulated mast cells when incubated with IL-4. Anti-ICAM-1 and an ti-IgE staining were increased over that of unstimulated cells when incubat ed with TNF-alpha or IL-4. Conclusions: In this model, TNF-alpha up-regulates mast cell surface recept ors and cell-bound IgE. Interleukin 4 up-regulates mast cell ICAM-1 and cel l-bound IgE, but down-regulates c-hit. Clinical Relevance: Conjunctival mast cells play a critical role in the pat hogenesis of atopic ocular disease. Characterization of the expression and regulation of mast cell surface receptors is important to the development o f potential novel treatments for ocular inflammation.