Changes in the acute phase complement component and IL-6 levels in patients with chronic hepatitis C receiving interferon alpha-2b

In order to study the effect of interferon alpha on the levels of acute pha se complement proteins in vivo, serum concentrations of C9 and C1-inhibitor (C1-INH) were measured in patients with chronic hepatitis C before and 3 m onths after the beginning of interferon alpha 2b therapy. Serum levels of t he activation product of terminal complement pathway, C5b-9, HCV RNA and IL -6 were also determined. IFN alpha treatment significantly (P < 0.0001) inc reased the serum concentrations of both complement proteins. C5b-9 levels w ere found to significantly decrease during the same period of time. When th e patients were divided into responders or non-responders (more or less tha n 50% decrease in plasma HCV RNA concentrations) C9 and C1-INH levels were elevated only in the responder patients. There was no correlation between t he changes of IL-6 levels or the amounts of IFN alpha administrated on one hand, and the changes in the complement protein levels on the other. These findings suggest that the marked increase in the serum concentrations of th e acute phase complement proteins is a secondary phenomenon due to the IFN alpha-caused diminution of the viral load and the resulting immune complex- induced complement activation. (C) 2000 Published by Elsevier Science B.V. All rights reserved.