Preserved T-cell function in children and young adults with immune-tolerant chronic hepatitis B

Chronic hepatitis B (CHB) infection acquired perinatally or in early childhood has been associated with a prolonged phase of immune tolerance from viral exposure into early adulthood. The immune-tolerant phase of the disease is characterized by high levels of hepatitis B virus (HBV) DNA and normal liver biochemistry, with minimal or no fibrosis. We investigated whether the age of patients with CHB affects their antiviral immunity and whether children and young adults have a veritable state of immunologic tolerance.

We isolated T cells from different age groups of patients with CHB and used flow cytometric methods to measure production of effector and inflammatory cytokines (interferon, tumor necrosis factor, interleukin [IL]-17A, IL-22, and IL-8), T-helper (Th)2 cytokines (IL-10, IL-4), Th1 cytokines (IL-2 and IL-21), and the CC chemokine CCL3 (MIP-1). We also measured markers of T-cell exhaustion or inhibition (PD-1, LAG-3, TIM3, LAIR-1, and CTLA-4) and HBV-specific T cells.

Young patients with CHB have a Th1-cell cytokine profile and a partial profile of T-cell exhaustion. Direct quantification of the HBV-specific T-cell response showed that young patients with CHB have more HBV-specific T cells with the ability to proliferate and produce cytokines than adult patients with CHB.

HBV infection in younger patients is not associated with an immune profile of T-cell tolerance. On the contrary, children and young adults with chronic HBV infection have an HBV-specific immune profile that is less compromised than that observed in older patients.