Expression of the Interleukin-8 Receptors CXCR1 and CXCR2 on Cord-Blood-Derived Cultured Human Mast Cells

Abstract

BACKGROUND: An increase in mast cell number at sites of inflamed tissues has been observed. However, the expression of CXC chemokine receptors on human mast cells is poorly understood. METHODS: Cultured human mast cells were raised from human umbilical cord blood cells in the presence of stem cell factor and interleukin-6 (IL-6). The expression of surface chemokine receptors on the mast cells was analyzed by flow cytometry and that of mRNA was examined by the method of reverse transcriptase-polymerase chain reaction (RT-PCR). As functional assays for the receptors, mast cell migration was examined by a microchemotaxis assay and changes in the cytosolic free intracellular calcium concentrations ([Ca2+]i) was measured using fura-2-loaded mast cells, respectively. RESULTS: Expression of IL-8 receptors CXCR1 and CXCR2 was demonstrated by flow cytometry and of both mRNA by RT-PCR; however, CC chemokine receptors including CCR3 were not expressed on cord-blood-derived cultured human mast cells. IL-8 and its homologues showed chemotactic activity toward them in a dose-dependent manner, and IL-8 induced a dose-dependent rapid and transient increase in [Ca2+]i in the mast cells. CONCLUSIONS: Our results suggest the surface expression of functional CXCR1 and CXCR2 on cord-blood-derived cultured human mast cells.