Production of interleukins 10 and 12 by activated peripheral blood monocytes/macrophages in patients suffering from chronic hepatitis C virus infection with respect to the response to interferon and ribavirin treatment

Circulating monocytes/macrophages are important for the initiation of immune responses to hepatitis C virus (HCV). Their presentation capacities and production of immunoregulatory cytokines enable them to activate cellular immune responses which is critical in determining the outcome of infection. We used flow cytometry to examine the expression of a CD80 costimulatory molecule on the surface of peripheral blood CD14+ monocytes/macrophages and to analyse the production of IL10 and IL12 by these cells. Forty-three individuals (6 asymptomatic HCV carriers, 37 patients with chronic hepatitis C (CHC)) were enrolled in this study. Thirty-seven patients with CHC (23 responders and 14 non-responders, NR) received combination (interferon+ribavirin) treatment for 52 weeks. The baseline percentage of CD14+CD80+ peripheral blood monocytes/macrophages was high in patients with CHC (P<0.001) and returned to normal after the treatment. All patients with CHC showed significantly high production of IL10 (P<0.001). In asymptomatic HCV carriers production level of this cytokine tended to be higher than in patients with CHC (P<0.001). A baseline production of IL12 was higher in asymptomatic HCV carriers and patients with CHC compared to healthy controls (P<0.001). The level of IL12 production was increased in treatment responders whereas in NR returned to normal value. Our data argue against functional impairment of circulating monocytes/macrophages during HCV infection. Furthermore, the positive therapeutic outcome following combination treatment might associate with increased production of IL12 by these cells.