Association of C-type lectin 18 levels with extrahepatic manifestations in chronic HCV infection.

Mixed cryobulinemia (MC) is the most common chronic hepatitis C virus (HCV)-associated extrahepatic manifestation. C-type lectin 18 (CLEC18) is a novel secretory lectin that is abundantly expressed in hepatocytes and peripheral blood cells (PBCs). We investigated the associations between CLEC18 expression during HCV infection and the presence of extrahepatic manifestations. A total of 41 rheumatic patients with HCV infection (including 28 patients with MC syndrome), 45 rheumatic patients without infection, and 14 healthy subjects were enrolled. The CLEC18 levels in PBCs and serum were determined by using flow cytometry and enzyme-linked immunosorbent assay, respectively. Significantly higher CLEC18 levels were observed in patients with HCV infection (P < 0.001) and were positively correlated with HCV viral loads (γ = 0.56, P < 0.05). Among patients with HCV infection, significantly increased CLEC18 levels were observed in patients with MC syndrome, particularly in those with type II MC (P < 0.05). CLEC18 levels were associated with cryoglobulin and C4 levels (P < 0.05). CLEC18 was significantly associated with HCV infection, particularly in those with HCV-associated MC. CLEC18 levels were also positively correlated with MC disease activity, suggesting its involvement in MC pathogenesis. CLEC18 may be a novel indicator of HCV infection and a potential therapeutic target in rheumatic patients.