Selective binding of the truncated form of the chemokine CKβ8 (25–99) to CC chemokine receptor 1 (CCR1)

Abstract Human CC chemokine receptor 1 (CCR1) has been proposed as a receptor for CKβ8. To obtain conclusive evidence, binding–displacement studies of 125 I-CKβ8 (25–99) were performed on membranes of Chinese hamster ovary cells expressing human CCR1. The ic 50 for displacement of 125 I-CKβ8 (25–99) with CKβ8 (25–99) was 0.22 nM. The longer forms of CKβ8 (24–99 and 1–99) also displaced 125 I-CKβ8, with ic 50 values of 6.5 and 16 nM, respectively. Displacement profiles of 125 I-CKβ8 (25–99) on freshly prepared human monocytes indicated that CCR1 was the major receptor for CKβ8. We conclude that CCR1 is a receptor for different-length CKβ8 and that CKβ8 (25–99) has a similar affinity for CCR1 as macrophage inflammatory protein-1α (MIP-1α). The longer variants of CKβ8 are significantly less potent than CKβ8 (25–99) and MIP-1α on CCR1 and monocytes ( P