A prospective study of lymphocyte subpopulations and regulatory T cells in patients with chronic hepatitis C virus infection developing interferon-induced thyroiditis.

Objective: One of the side effects of interferon-alpha (IFN-α) therapy is interferon-induced thyroiditis (IIT). The role of lymphocyte subpopulations in IIT remains to be defined. The aim of this study was to assess different peripheral blood lymphocyte subpopulations, mainly CD4(+) CD25(+) CD127low/-FoxP3(+) regulatory T cells (Tregs), in patients with chronic hepatitis C virus (HCV) infection who developed IIT.
Design, Patients and Methods: From 120 patients with chronic HCV who started antiviral treatment, those who developed IIT (IIT patients) were selected and compared with patients who did not develop IIT (Co-HCV). Peripheral blood mononuclear cells were obtained before treatment (BT), mid-treatment (MT), end of treatment (ET), 24 weeks post-treatment (PT) and at appearance of IIT (TT).
Results: Eleven patients developed IIT: three Hashimoto's thyroiditis, one Graves'disease, one positive antithyroidal antibodies, one nonautoimmune hypothyroidism and five destructive thyroiditis. During antiviral treatment, an increase in CD8(+) and in Tregs was observed in both groups. A decrease in CD3(+) , CD19(+) and NKT lymphocyte subpopulations was also observed (all P < 0·05). However, no changes were observed in the percentage of CD4(+) , CD3(+) γδ(+) and iNKT lymphocytes, Th1/Th2 balance and Bcl2 expression on B cells when BT was compared with ET. At the appearance of IIT (TT), IIT patients had a higher Th1 response (CCR5(+) CCR7(-) ) (P < 0·01) and a higher Tregs percentage (P < 0·05) than Co-HCV.
Conclusions: Our results point to the immunomodulatory effects of IFN-α on different lymphocyte subpopulations and a possible role of Th1 response and Tregs in patients with HCV who developed IIT.
(© 2011 Blackwell Publishing Ltd.)