CLONING AND CHARACTERIZATION OF AN OVINE INTERLEUKIN-10-ENCODING CDNA

Expression of the interleukin 10-encoding (IL-10) mRNA by ovine (ov-) cells, in response to mitogenic stimulation, was assessed by Northern blot and polymerase chain reaction (PCR) analyses using a human (hu) IL-10 cDNA probe and oligodeoxyribonucleotide primers based on homologous regions of the human and murine IL-IO cDNA sequences. A 315-bp cDNA generated by the PCR analysis was cloned and used to screen a lipopolysaccharide-stimulated alveolar ov-macrophage cDNA library, The full-length ov-cDNA sequence isolated translates to a protein of 177 amino acids (aa) with a predicted 18-aa leader sequence and molecular mass of 20 165 Da. Expression in a mammalian system demonstrated that the ov-cDNA encoded a protein with the expected IL-10 biological activity. Both recombinant huIL-10 and supernatants from COS cells transfected with an expression vector containing the ovIL-10 cDNA inhibited production of IL-1 and tumour necrosis factor-alpha by ov-alveolar macrophages. Genomic DNA analysis indicated ovIL-10 exists as a single gene within the ov-genome.