Beckman Cd294-Pe, Bm16, 100 Tests, Ruo

CD294, also known as CRTH2, is a seven-transmembrane G-protein-coupled receptor known as the chemoattractant receptor-homologous molecule expressed on Th2 cells. The deduced amino acid sequence of CRTH2 suggests two potential N-glycosylation sites at the first extracellular domain and a unique long cytoplasmic tail including four consensus sites for protein kinase C phosphorylation. Two G protein-coupled receptors, Prostaglandin D receptor (DP), and CRTH2 have been identified as receptors for Prostaglandin D2 (PGD2), but they differ in their signaling pathways. PGD2 is the major metabolite of arachidonic acid produced by allergen-activated mast cells and has been implicated in various allergic diseases as a proinflammatory lipid mediator. CRTH2 molecule is preferentially expressed on human T-helper (Th) 2 and T cytotoxic (Tc) 2 cells but not on Th1 and Tc1 cells. CRTH2 is the most reliable surface marker selectively associated with circulating T (Th and Tc) cells able to produce IL-4 (as well as IL-5 and IL-13) and not IFNγ. On normal whole blood leucocytes, CD294 is highly expressed on basophils and eosinophils, as well as Th2 and Tc2 cells. The expression of CD294 in peripheral blood mononuclear cells (PBMCs) is highly restricted to an activated state of Type 2 cells: i.e. CD25neg T cells do not express CD294. CD294 may be expressed (weakly) on some monocytes and/or dendritic cells (CD14dim,CD16pos,HLA-DRpos,CD33pos). CD294 may act in mediating the recruitment and/or activation of basophils, eosinophils and Th2 cells at sites containing mast cells activated by invading allergens. CRTH2, but not DP, induces migration of Th2 cells, eosinophils and basophils in response to PGD2.