Detectable expression of IL-35 in CD4+ T cells from peripheral blood of chronic Hepatitis B patients

Epstein–Barr virus-induced gene 3 (Ebi3) and the p35 subunit of IL-12 have been reported to form a heterodimeric cytokine, named IL-35, in human and mouse. In mice, IL-35 has been shown to be constitutively expressed by CD4+CD25+Foxp3+ regulatory T cells (Tregs) and suggested to contribute to their suppressive activity. However, human CD4+CD25+Foxp3+ Tregs do not constitutively express detectable amounts of IL-35 in both mRNA and protein levels. Circulating CD4+CD25+ Treg frequency of chronic Hepatitis B patients significantly correlates with serum viral load. In this study, we investigated whether IL-35 expression could be detected in CD4+ T cells from peripheral blood of chronic Hepatitis B patients. Using both RT-PCR and immunoprecipitation plus Western blot analysis, we demonstrated that IL-35 expression could be detected in the CD4+ T cells from peripheral blood of Chronic Hepatitis B patients.