Turkey and chicken interferon-gamma, which share high sequence identity, are biologically cross-reactive

Turkey and chicken interferon-gamma (IFN-gamma) share high identity (96.3% and 97% at the nucleotide and amino acid level, respectively). As such, we predicted that they would be functionally cross-reactive. To test this hypo thesis, we produced recombinant turkey and chicken IFN-gamma, and compared their biological properties. Recombinant turkey and chicken IFN-gamma both induce HD11 cells (a chicken macrophage cell line) and LSTC-IAH30 cells (AL V-J-transformed turkey macrophages) to produce nitric oxide (NO), as measur ed in an avian IFN-gamma bioassay. Polyclonal and monoclonal antibodies, ca pable of neutralising the effect of chicken IFN-gamma on HD11 cells, were a lso shown to inhibit the activity of turkey IFN-gamma on these cells. The a ntibody neutralisation effect on bath turkey and chicken IFN-gamma was show n by a significant reduction in NO production by HD11 cells when the neutra lising antibodies were present in the bioassay. FAGS analysis showed that H D11 and LSTC-IAH30 cells share some cell surface markers. (C) 2000 Elsevier Science Ltd. All rights reserved.