The expression kinetics of CD137 in chronic hepatitis C patients treated with pegylated-interferon and ribavirin.

OBJECTIVE: CD137, a member of the tumor necrosis factor receptor family, generates co-stimulatory signals leading to T-cell activation and proliferation for viral eradication. We examined the expression kinetics of CD137 to validate whether it can affect treatment outcomes of chronic hepatitis C (CHC) patients. METHODS: The expression of CD137 on peripheral blood mononuclear cells (PBMC) from 50 CHC patients and 20 healthy controls was analyzed by flow cytometry. CD137 expression levels were examined before treatment, and every 4 weeks during treatment until week 24 or 48, and at the 24-week follow-up. RESULTS: CD137 expression on PBMC was significantly lower in CHC patients than controls (15.5 ± 7.8% vs 23.4 ± 5.2%; p < 0.05). Patients with sustained virological response (SVR) showed higher level of CD137 expression on PBMC than treatment failures at week 4 (20.11% vs 10.97%; p < 0.05) and week 12 (15.48% vs 5.74%; p < 0.01). CD137 expression on CD4 T cells was also higher in patients with SVR at week 8 (7.75% vs 3.29%; p < 0.05). CD137 expression on PBMC from patients with SVR recovered to the control level at the 24-week follow-up. In multivariate analysis, the increased expression of CD137 at week 4 and genotype non-1 were significantly associated with SVR. CONCLUSIONS: The increased expression of CD137 within 12 weeks after the initiation of interferon therapy might be associated with a successful treatment outcome. Modulation to improve expression of CD137 might improve efficacy of CHC treatment.