Serum IL-18 concentration does not depend on the presence of HCV-RNA in serum or in PBMC

Background/Aims: To establish if serum IL-18 concentration depends on presence of HCV-RNA in serum or in peripheral blood mononuclear cells. To relate serum levels of IL-18 to histological parameters of chronic hepatitis C. Methodology: IL-18 serum concentration was measured by ELISA in 92 patients with chronic hepatitis C (43 serum HCV-RNA positive and 49 serum HCV-RNA negative after treatment). In 13 patients from the latter group HCV-RNA persisted in peripheral blood mononuclear cells, while in 34 it was negative. Thirty-five healthy individuals were the control. Results: IL-18 level was higher in 92 patients than in the control (77 +/- 31pg/mL vs. 58 +/- 34pg/mL; p=0.002). Significant difference was found between the control and HCV-RNA positive (80 +/- 29pg/mL, p=0.002), HCV-RNA negative (75 +/- 32pg/mL, p=0.019), patients who eliminated HCV-RNA from serum and from PBMC (85 +/- 36pg/mL, p=0.002). IL-18 concentration was higher in serum HCV-RNA positive than in serum HCV-RNA negative patients (p=0.019) and it was related to histological inflammatory activity (p=0.008). Conclusions: Serum IL-18 concentration is related to presence of HCV-RNA in serum, in PBMC and liver inflammation. Increased level of this cytokine in patients with undetectable HCV-RNA may result from occluded persistence of the virus in the liver.