CCR3 (C-C chemokine receptor type 3) is a seven transmembrane G-protein coupled receptor (GPCR) that acts as a key regulator in the homeostasis of the immune system. The receptor is responsible for recruiting eosinophils to local inflammatory tissues.

CCR3 is the endogenous receptor for Eotaxin, C-C motif chemokine 11 (CCL11). The binding between CCR3 and CCL11 activates G-protein-dependent signaling pathways and thus enables the release of eosinophils progenitor cells and mature eosinophils to the affected tissue. Studies have shown that deficiency in CCR3 protein may reduce the binding of Eotaxin and inhibition of phosphatidylinositol-3-kinase (PI3K) signaling pathway activation and the inactivation of its subunit PI3Kγ¹. Other CCR3 ligands include CCL5, CCL24, CCL26, CCL8, CCL7, and CCL12¹.

CCR3 is linked to several type-I allergy diseases, including allergic rhinitis. In addition to CCR3 expression in eosinophils, CCR3 is also expressed in basophils, microglia, astrocytes and neurons in both the developing and adult brain^1,2.

The expression of CCR3 increases following human immunodeficiency virus infection and in reactive microglia and astrocytes around the amyloid deposits in Alzheimer’s disease².