Abstract
Type I IFN holds a critical role in host defence, providing protection against pathogenic organisms through coordinating a pro-inflammatory response. Type I IFN provides additional protection through mitigating this inflammatory response, preventing immunopathology. Within the context of viral infections, type I IFN signalling commonly results in successful viral clearance. Conversely, during bacterial infections, the role of type I IFN is less predictable, leading to either detrimental or beneficial outcomes. The factors responsible for the variability in the role of type I IFN remain unclear. Here, we aimed to elucidate differences in the effect of type I IFN signalling on macrophage functioning in the context of TLR activation. Using RAW 264.7 macrophages, we observed the influence of type I IFN to be dependent on the type of TLR ligand, length of TLR exposure and the timing of IFN-β signalling. However, in all conditions, IFN-β increased the production of the anti-inflammatory cytokine IL-10. Examination of RAW 264.7 macrophage function showed type I IFN to induce an activated phenotype by up-regulating MHC II expression and enhancing killing activity. Our results support a context-dependent role for type I IFN in regulating RAW 264.7 macrophage activity.