HBsAg and Immune Competency; is HBsAg a Mere Biomarker or a Therapeutic Target for Chronic Hepatitis B?

Hepatitis B virus (HBV) is a main cause of hepatocellular carcinoma (HCC) development. Although controversial, it is increasingly recognized that the immune responses directed against infected hepatocytes drive hepatic inflammation and tissue injury. Here we extended our previous findings to report that serum surface antigen (HBsAg) levels are a biomarker not only for HBV-specific immunity, but also for ongoing non-specific immune activation. We found that the HBV-specific T cell responses in patients with HBsAg < 500 IU/mL, while significantly higher than those in patients with HBsAg > 50,000 IU/mL, had already reached levels comparable to patients with seroclearance. In addition, lower HBsAg levels were associated with reduced non-specific immune activation, while no further reduction was observed with HBsAg < 500 IU/mL. We propose HBsAg is a therapeutic target for reducing inflammation.