Prostaglandin D2 and interleukin-5 reduce CRTH2 surface expression on human eosinophils

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Background: Recently, a second prostaglandin D2 (PGD2) receptor, chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2), was identified. Because PGD2 was reported to have chemotactic activity on eosinophils, CRTH2 expressed on eosinophils attracted interest as a receptor associated with eosinophil migration to, and accumulation at, inflammatory sites. To elucidate the mechanism regulating the expression of CRTH2 on eosinophils, the effects of PGD2, interleukin (IL)-4, IL-5 and interferon (IFN)-γ on CRTH2 expression were investigated. Methods: Blood eosinophils were purified using Percoll and anti-CD16 antibody coated magnetic beads. Eosinophils were incubated with PGD2 and/or IL-4, IL-5 and IFN-γ. The expression of CRTH2 on eosinophils was measured using a FACScan cytometer (Becton Dickinson Immunocytometry Systems, San Jose, CA, USA). Results: Prostaglandin D2 and IL-5, but not IL-4 and IFN-γ, downregulated the expression of CRTH2 on eosinophils. Furthermore, PGD2- and IL-5-induced downregulation of CRTH2 on human eosinophils was inhibited by phenylarsine oxide, a receptor internalization inhibitor. Conclusions: These results suggest that PGD2 and IL-5 regulate CRTH2 expression on eosinophils through CRTH2 internalization. The decreased expression of CRTH2 on tissue eosinophils may make these cells remain at the site of allergic inflammation.
Japanese Society of Allergologyの論文