The human C-X-C chemokine IL-8 is a potent neutrophil chemotactic and activating factor (1). Two distinct cell surface receptors can interact with the IL-8 molecule. These two structures are known as IL-8RA (type I or CXCR-1) and IL-8RB (type II or CXCR-2) (2, 3). The two receptors share 77% amino acid homology and are both members of the rhodopsin superfamily of G protein-linked receptors that span the cell membrane with seven hydrophobic transmembrane domains. Of the two IL-8 receptors, only IL-8RA exclusively binds IL-8 (4). A third IL-8 binding structure, known as the Duffy blood group antigen, has been identified on red blood cells (5). IL-8RA expression has been documented on neutrophils, monocytes and a small population of T cells (2).
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2. Holmes, W.E. et al. (1991) Science 253:1278.
3. Murphy, P.M. and H.L. Tiffany (1991)
4. LaRosa, G.J. et al. (1992) J. Biol. Chem. 267:25402.
5. Horuk, R. et al. (1993) Biochemisry 32:5733