Impaired function of CD4+/CD25+ T regulatory lymphocytes characterizes the self-limited hepatitis A virus infection.

BACKGROUND AND AIM: Hepatitis A virus (HAV) causes a transient illness leaving permanent protection against reinfection. Few data are available on the regulatory mechanisms involved in the CD4+ T helper activation. We aimed to investigate the frequency and function of CD3+/CD4+/CD25+ T cells with regulatory function (Tregs) during acute HAV infection. METHODS: We enrolled 35 consecutive patients and 15 healthy donors, enumerated Tregs by flow cytometry assay and evaluated, after immunomagnetical sorting with magnetic beads, their ability to inhibit the proliferation of CD4+/CD25- T lymphocytes at different ratios (1:1, 1:10, 1:20). RESULTS: All patients had the usual course of infection. Our immunological analysis showed Tregs frequency in these patients (6.5% [range, 5-8.8%]; 36 [range, 10-87] cells) did not have any statistical difference compared with healthy donors (6% [range, 5-8%]; 48 (range, 23-71) cells), while their ability to suppress CD4+/CD25- was drastically reduced at different ratios (Mann-Whitney U-test; ratio 1:1, 93% vs 72%, z = -3.34, P < 0.0001; ratio 1:10, 86% vs 51%, z = -4.04, P < 0.001; ratio 1:20, 56% vs 30%, z = -3.43, P < 0.0001). After the seroconversion, CD4+/CD25+ frequency and function in HAV-infected patients did not differ from healthy individuals. CONCLUSION: CD4+/CD25+ T cells seem to be impaired in their function during the HAV acute infection. This evidence might help to determine an optimal T helper cell immune network that is a predisposing factor for a self-limiting disease.

Flow cytometry assay of myeloid dendritic cells (mDCs) in peripheral blood during acute hepatitis C: possible pathogenetic mechanisms.

AIM: To asses the expression of myeloid dendritic cells (CD11c+) subset during acute HCV hepatitis and its possible involvement in natural history of the infection. METHODS: We enrolled 11 patients with acute hepatitis C (AHC) (Group A), 10 patients with acute hepatitis A (AHA) (as infective control-Group B) and 10 healthy donors (group C) in this study. All patients underwent selective flow cytometry gating strategies to assess the peripheral number of the myeloid dendritic cells (mDCs) to understand the possible role and differences during acute hepatitis. RESULTS: Eight of 11 patients with acute HCV hepatitis did not show any increase of mDCs compared to healthy individuals, while a significant decrease of mDCs was found in absolute cell count (z = -2.37; P<0.05) and percentage (z = -2.30; P<0.05) as compared with AHA. On the contrary, The remaining three patients of the group A had a higher mDCs number and percentage as occur in group B. Interestingly, after six months, those patients did not show any increase of mDCs subset were chronically infected. while the three subjects with an increase of peripheral mDCs, as in HAV acute infection, resolved the illness. CONCLUSION: The lack of increase of mDCs during acute hepatitis C might be an important factor involved in chronicization of the infection.