The influence of North American Aboriginal ethnicity on pro-inflammatory and anti-inflammatory cytokine responses to IFN-alpha.

North American Aboriginals have an enhanced propensity to clear HCV infection. Interferon (IFN)-alpha is a critical agent in the clearance of hepatitis C virus (HCV) and other viruses; therefore the influence of Aboriginal ethnicity on IFN-alpha responses was investigated in healthy Caucasian population control and Aboriginal cohorts. Cohort peripheral blood mononuclear cells produced similar levels of IFN-alpha upon culture with reovirus, an innocuous virus capable of triggering IFN-alpha synthesis. In addition, similar IFN-gamma synthesis was observed in the presence IFN-alpha or reovirus. In contrast, Caucasian supernatants exhibited greater IL-10 levels (P<0.005), contributing to the overall cytokine balance as assessed by IFN-gamma/IL-10 ratios being consistently elevated in the Aboriginal cohort. The potential of HCV proteins to alter IFN-alpha cytokine induction was also investigated. Although there was some indication that HCV proteins might increase IFN-alpha induced IL-10 synthesis in Caucasians and conversely, IFN-gamma synthesis in Aboriginals, the addition of HCV proteins did not influence IFN-gamma/IL-10 ratios. Finally, signal transducer and activator of transcription (STAT) 3 nuclear translocation was examined by western blot because it is a required intermediate in IFN-alpha induced IL-10 synthesis. Supporting the differential IL-10 production, IFN-alpha and core synergistically enhanced STAT3 nuclear translocation in Caucasian (P<0.05); whereas, nuclear translocation of STAT3 remained unchanged in Aboriginal cells. Taken together, these findings suggest that ethnicity may influence certain responses to IFN-alpha, possibly even in the presence of viral agents. These differences could impact early immune events allowing for enhanced viral clearance in Aboriginal populations.