CD4 and chronic hepatitis B virus infection: Study from Liu et al. (2011) provided first evidence that HBV may act as an inducer for the CD4+ T cells to initiate IL-35 secretion based on the data that both the mRNA expression of EBI3/p35 and the protein secretion of IL-35 were detectable in circulating CD4+ T cells in patients with chronic hepatitis B. However, there remains a lack of research on IL-35 derived from Breg cells in HBV infection.