Cloning, sequencing, expression and inflammatory activity in skin of ovine interleukin-8.

Ovine IL-8 (oIL-8) cDNA was obtained by probing a spleen cell cDNA library with human IL-8 (hIL-8) cDNA. The oIL-8 cDNA was 1434 base pairs long with a single open reading frame encoding a 101 amino acid precursor protein of relative molecular mass 11,268. The inferred amino acid sequence has 78, 82, 84 and 67% similarity with human, rabbit, porcine and guinea-pig IL-8, respectively. By analogy with the most prevalent form of hIL-8, a 72 amino acid form of oIL-8 was expressed as a fusion protein containing glutathione-S-transferase and purified by affinity chromatography on a glutathione-Sepharose column yielding 8 mg IL-8/L broth culture. The fusion protein lacked chemotactic activity for ovine neutrophils, whereas the 72 amino acid form of oIL-8 was equipotent with rhIL-8. At 6 and 24 h after intradermal injection of 10(-9) mol oIL-8, there was intense accumulation of neutrophils, and very mild accumulation of eosinophils, CD5, CD4 and T19 (a gamma delta TCR subset) cells but not CD8 cells. The availability of roIL-8 and its cDNA probes will permit the role of this important member of the IL-8 family of chemotactic cytokines to be determined in inflammatory diseases of sheep.