Bovine interleukin-12 and modulation of IFNγ production

The effects of IL-12 on the responses of cattle peripheral blood mononuclear cells (PBMC) to bovine respiratory syncytial virus (BRSV) antigen and ovalbumin (OVA) were tested, in vitro. IL-12 did not affect the proliferative responses of PBMC to these antigens but markedly accelerated and augmented the level of IFNγ secreted. When tested on lymphoblasts rather than resting T-cells IL-12 also enhanced proliferation. In contrast IL-4 and, to greater extent, IL-10 inhibited the response. The effect of IL-12 on IFNγ synthesis was confirmed at the level of IFNγ. mRNA expression using Taqman® PCR. CD4 and CD8 T-cell populations produced IFNγ, however, CD4 T-cells comprised the largest contributors to the IFNγ production. γ/δ T-cells did not contribute markedly. A comparison of the species cross-reactivity showed bovine IL-12 was also active in the human system. This study shows that antigen-driven responses in cattle can be significantly influenced by exogenous cytokines and suggests the IL-12/IL-10 balance is crucial for regulation of IFNγ.