Studies on ovine tumour necrosis factor alpha

• Main Author: Green, Ian R.
• Published: University of Edinburgh 1994
• Subjects: 636.089
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.651785

Tumour necrosis factor alpha (TNFα), a mediator of inflammatory responses and pathologies of a wide variety of diseases, has been extensively studied in humans and mice. However, little has previously been known about this cytokine in the sheep, a species of value not only to the agricultural industry, but also as a laboratory animal. In this work, the cDNA encoding ovine TNFα has been amplified, cloned, sequenced and used to express recombinant ovine TNFα (rovTNFα). The latter has been partially purified, characterised and used to raise both poly- and mono- clonal antibodies. The sequence of ovine TNFα shows a high degree of homology to those of other species. Certain regions, which are known to be structurally or functionally important to the mRNA and/or protein, are particularly well conserved. Consequently, rovTNFα displays several biological activities previously noted for TNF'sα of other species, including cytotoxicity, enhancement of thymocyte and fibroblast profileration and cartilage-degrading and anti-viral activities. However, whilst rovTNFα is active in assays on ovine cells at concentrations comparable to those observed in similar assays for other species, it is 1000 fold less active than recombinant human TNFα (rhTNFα) in cytotoxicity assays on TNF-sensitive murine (L929) cells, whose general lack of species specificity allows their use in detecting TNF'sα from many sources. A monoclonal antibody raised to rovTNFα detects a glycoprotein of appropriate size for mature ovine TNFα in the supernatants of stimulated ovine cell cultures. As in other species both ovine TNFα mRNA and protein are rapidly inducible. Such supernatants repeatedly have no activity in cytotoxicity assays (sensitive to 30pg rhTNFα/ml) on L929 cells, in spite of many containing >1ng ovine TNFα/ml.