Kinetics of ovine interferon-gamma production: detection of mRNA and characterisation of biological activity.

The kinetics of interferon-gamma (IFN-gamma) production were studied in sheep mesenteric lymph node (MLN) cells at the molecular level using an ovine IFN-gamma cDNA probe and by bioassay which was verified by blocking antiviral activity with a monoclonal antibody (Mab) against recombinant bovine IFN-gamma IFN-gamma mRNA appeared in MLN cells within 4 h of stimulation with phorbol ester and Concanavalin A and was not detectable by 72 h after stimulation. Biologically active IFN-gamma appeared in the culture supernatants 8 h after stimulation and was still present 96 h later when de novo synthesis had terminated. Acid dialysis and Mab neutralisation demonstrated conclusively that native ovine IFN-gamma is a pH 2 labile cytokine.