Endocrine Abstracts

Introduction: Interferon-α (IFN-α) exerts different immune effects and is used in current therapy for chronic hepatitis C virus (HCV) infection. One of the side-effects of IFN-α therapy is interferon-induced thyroiditis (IIT). The role of lymphocyte subpopulations in IIT remains to be defined.

Objective: This study was conducted to assess different peripheral blood lymphocyte subpopulations, mainly regulatory CD4⁺CD25⁺CD127l^ow/−FoxP3⁺T cells (Tregs), in patients with chronic HCV infection who developed IIT.

Patients and methods: From 120 patients with HCV who started antiviral treatment, those who developed IIT (IIT patients) were selected and compared with patients who did not developed IIT (Co-HCV). Peripheral blood mononuclear cells (PBMC) 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: 3 Hashimoto’s thyroiditis, 1 Graves’ disease, 1 positive antithyroidal antibodies, 1 non-autoimmune hypothyroidism and 5 destructive thyroiditis. During combined antiviral treatment, a significant increase in CD8⁺ lymphocytes and in Tregs was observed in both groups. A significant 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 HCV patients who developed IIT.