The frequency of peripheral blood T lymphocytes specific to HCV derived proteins, NS3, NS4, NS5 and core was determined by means of IL-10 ELISPOT assay. The data is representative of all experiments done in triplicate and the standard error bars are demonstrated. Patients with hepatic fibrosis (HFC, n=25, black bars) demonstrated significantly higher frequency of IL-10 producing HCV-specific T lymphocytes compared to patients with hepatic inflammation (HIN, n=49, white bars) and healthy control individuals (n=20, grey bars, p<0.05). The frequency of T lymphocytes reactive to the mumps antigen was comparable.