Design and evaluation of small peptides mapping the exposed surface of IL-8

In an effort to determine which regions of IL-8 are involved in interactions with its receptors, eight peptides were designed to correspond to distinct exposed regions of the IL-8 monomer, using the proton NMR-derived structure of the dimer as a basis. The peptides were evaluated singularly, and as equimolar mixtures of two to six peptides, in an IL-8 receptor binding assay and found to have no binding interaction with either alpha or beta IL-8 receptor as single peptides or mixtures of two peptides. In contrast, one of these peptides having the sequence AVLPRSAKEL, which corresponds to the N-terminal 10 amino acid residues of the 77 amino acid form of IL-8, exhibited potent chemotactic activity in human neutrophils. These results indicate that there is no contiguous ligand that can be designed based on the NMR and X-ray determined structure of IL-8 and that there may be multiple receptors responsible for neutrophil activation and chemotaxis.