In a study of hepatic flares in chronic hepatitis B conducted by Tan et al., no increases in CD25+FoxP3+CD4+ T cells or CD39+CD4+ T cells were observed at any of the time points tested, suggesting that these cells may not play any role in inhibiting HBV-specific T cell responses in vivo [37]. Here, ENTPD1 is linked to chronic hepatitis B virus infection.