Distinct phenotype and function of circulating Vδ1+ and Vδ2+ γδT-cells in acute and chronic hepatitis B.

Hepatitis B virus (HBV) persists with global and virus-specific T-cell dysfunction, without T-cell based correlates of outcomes. To determine if T-cells are altered in HBV infection relative to clinical status, we examined the frequency, phenotype and function of peripheral blood V1(+) and V2(+)T-cells by multi-parameter cytometry in a clinically diverse North American cohort of chronic hepatitis B (CHB), acute hepatitis B (AHB) and uninfected control subjects. We show that circulating T-cells were comprised predominantly of CD3(hi)CD4(-) V2(+)T-cells with frequencies that were 2-3 fold higher among Asian than non-Asian Americans and inversely correlated with age, but without differences between CHB, AHB and control subjects. However, compared to control subjects, CHB was associated with increased Tbet(hi)Eomes(dim) phenotype in V2(+)T-cells whereas AHB was associated with increased Tbet(hi)Eomes(dim) phenotype in V1(+)T-cells, with significant correlations between Tbet/Eomes expression in T-cells with their expression of NK and T-cell activation and regulatory markers. As for effector functions, IFN/TNF responses to phosphoantigens or PMA/Ionomycin in V2(+)T-cells were weaker in AHB but preserved in CHB, without significant differences for V1(+)T-cells. Furthermore, early IFN/TNF responses in V2(+) T-cells to brief PMA/Ionomycin stimulation correlated inversely with serum ALT but not HBV DNA. Accordingly, IFN/TNF responses in V2(+)T-cells were weaker in patients with CHB with hepatitis flare compared to those without hepatitis flares, and this functional deficit persisted beyond clinical resolution of CHB flare. We conclude that circulating T-cells show distinct activation and differentiatiation in acute and chronic HBV infection as part of lymphoid stress surveillance with potential role in clinical outcomes. Author summary We examined circulating T-cells in a North American cohort with chronic hepatitis B (CHB) and acute hepatitis B (AHB) compared to uninfected control subjects. While frequencies and composition of circulating T-cells were preserved in AHB and CHB, T-cells showed distinct and innate phenotypes based on the expression of Tbet/Eomes in association with various NK/T-cell markers. Notably, IFN/TNF responses to phosphoantigens and PMA/Ionomycin were preserved in CHB, but weaker in AHB compared to uninfected control subjects, in association with NKG2A/CD94 but not PD1. Furthermore, early IFN/TNF responses in V2(+) T-cells to brief PMA/Ionomycin stimulation showed significant inverse correlations with serum alanine aminotransferase, a measure of hepatocellular injury, and were persistently deficient in CHB subjects with hepatitis flare compared to those without such flares. Finally, V2(+) T-cells were significantly enriched for Tbet(hi)Eomes(dim) phenotype in associations with their expression of NK and T-cell activation and regulatory markers, suggesting a role for Tbet in T-cell differentiation and function. We conclude that circulating T-cells show distinct activation and differentiation in acute and chronic HBV infection as part of lymphoid stress surveillance with potential role in clinical outcomes.