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 lib rary 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 precur sor protein of relative molecular mass 11 268. The inferred amino acid sequence has 78, 82, 84 and 67% similarity with human, rabbit, porcin e and guinea-pig IL-8, respectively. By analogy with the most prevalen t form of hIL-8, a 72 amino acid form of oIL-8 was expressed as a fusi on protein containing glutathione-S-transferase and purified by affini ty chromatography on a glutathione-Sepharose column yielding 8 mg IL-8 /L broth culture. The fusion protein lacked chemotactic activity for o vine neutrophils, whereas the 72 amino acid form of oIL-8 was equipote nt with rhIL-8. At 6 and 24 h after intradermal injection of 10(-9) mo l oIL-8, there was intense accumulation of neutrophils, and very mild accumulation of eosinophils, CD5, CD4 and T19 (a gamma delta TCR subse t) cells but not CD8 cells. The availability of roIL-8 and its cDNA pr obes will permit the role of this important member of the IL-8 family of chemotactic cytokines to be determined in inflammatory diseases of sheep.