MOLECULAR-IDENTIFICATION OF PORCINE INTERLEUKIN-10 - REGULATION OF EXPRESSION IN A KIDNEY ALLOGRAFT MODEL

Clones encoding porcine interleukin 10 (IL-10) were isolated from a cD NA library produced from phytohemagglutinin-activated pig peripheral b lood mononuclear cells, The porcine IL-10 nucleotide sequence was foun d to be highly homologous to the rat, mouse, and human IL-10 counterpa rts and to one of the open reading frames from the Epstein-Barr virus, In addition, pig IL-10 caused inhibition of gamma-interferon gene tra nscription as determined by a bioassay, To investigate the possible im munomodulatory role of IL-10, its expression during the induction of t olerance to kidney allografts by cyclosporin A in miniature swine was also investigated. Delayed expression and higher levels of IL-10 were observed in tolerant animals compared with animals rejecting their all ografts. Since tolerance is achieved by a short course of cyclosporin A, we have also studied the in vitro effect of this drug on IL-10 gene transcription in blood mononuclear cells and have found that cyclospo rin A inhibits IL-10 gene activation in T cells but does not interfere with IL-10 transcription in lipopolysaccharide-activated cells. These results suggest that the overexpression of IL-10, observed in cell po pulations infiltrating grafts from tolerant animals, may be a function of monocytes and/or B cells.