Investigation of CD4+CXCR5+ follicular helper T cell frequency and expression of related functional molecules in peripheral blood of hepatitis C virus patients

Objective To determine whether hepatitis C virus (HCV) infection is associated with increased frequency of the CD4+ follicular helper T (Tfh) subset in peripheral blood and to investigate their potential function contribution to the HCV-induced immune response by measuring expression levels of the Tfh cell-related molecules inducible T cell costimulator (ICOS) , programmed death-1 (PD-1) , and T cell immunoglobulin and mucin domain-containing protein-3 (Tim-3) .Methods Thirty-one patients with chronic HCV and nine patients with spontaneously resolved (SR) -HCV infection, all without prior (six months) treatment, were recruited for study.Twelve healthy individuals were recruited for use as controls.Peripheral blood samples of cases and controls were collected.Peripheral blood mononuclear cells were isolated and subjected to flow cytometry to measure the frequency of Tfh cells (by detecting CD4+CXCR5+) and their surface expression of ICOS, PD-1, and Tim-3.Serum concentrations of IL-21 and HCV antibodies were detected by enzyme-linked immunosorbent assay and of globin by an automated biochemistry analyzer.The HCV RNA titer was quantified by real-time PCR.Multiple comparisons were made by one-way ANOVA test, and correlation analysis was carried out by Spearman′s rank correlation test.Results All HCV-infected patients, including the SR-HCV cases, showed a significantly higher CD4+ T cell ratio, than the healthy controls (both P<0.05) ;however, the chronic HCV patients showed a significantly higher CD4+CXCR5+ ratio than the SR-HCV cases and healthy controls (both P<0.05) .All HCV-infected patients, including the SR-HCV cases, showed significantly higher levels of ICOS+/PD-1+/Tim-3+ cells in the CD4+CXCR5+ Tfh cells than the healthy controls (all P<0.05) .the="" hcv-infected="" patients="" showed="" but="" not="" lower="" levels="" of="" serum="" il-21="" than="" the="" healthy="" controls="" both="" p="">0.05) .The HCV RNA load was inversely correlated to frequency of CD4+CXCR5+ Tfh cells.Conclusion HCV infection is associated with increased frequency of Tfh cells, which may contribute functionally to the anti-viral immune response in a manner distinctive from the CD4+ (IL-21-producing) parent population.