Identification of a common receptor for three types of rat cytokine-induced neutrophil chemoattractants (CINCs)

Rat cytokine-induced neutrophil chemoattractant-1 (CINC-1), CINC-2 and CINC-3/macrophage inflammatory protein-2 (MIP-2), members of the CXC chemokine family, are potent chemotactic factors for neutrophils. In order to identify the receptor for CINCs, rat CXC chemokine receptor 2 (CXCR2) was cloned and expressed in HEK293 cells. CINC-1, CINC-2 and CINC-3 induced calcium mobilizations dose-dependently in CXCR2-transfected cells, whereas formyl-methionyl-leucyl-phenylalanine (FMLP) did not. CINC-3 induced enhancement of cytoplasmic calcium concentration more potently than CINC-1 and CINC-2, and desensitized calcium transients induced by CINC-1 and CINC-2, which were essentially identical to those observed in rat neutrophils. In addition, anti-CXCR2 serum inhibited neutrophil chemotactic activities of three types of CINCs almost completely. The mutant CINC-3, whose amino-terminal amino acid sequence (SELR) was replaced to AAR, lost chemotactic activity of its own but inhibited that of CINC-1 and CINC-2 potently, and that of CINC-3 weakly. The results indicate that rat CXCR2 on neutrophils is the unique receptor for all three types of CINCs, and CINC-1/-2 and CINC-3 exert different biological activities through the common receptor.