Expansion of peripheral blood CD5+ B cells is associated with mild disease in chronic hepatitis C virus infection

BACKGROUND/AIMS: Hepatitis C virus (HCV) infection is associated with the development of chronic liver disease and extra-hepatic manifestations, which include autoantibody production, immune-mediated diseases such as cryoglobulinaemia and B-cell lymphoproliferation. Recent identification of intra-hepatic clonal B cells capable of rheumatoid factor production, selective infection of B cells over T cells and of an HCV receptor on B lymphocytes strongly supports a central role for these cells in the immune response to HCV infection. In particular, CD5+ B cells which are capable of producing natural antibodies with autoreactive specificities are likely to be important in the development of HCV-associated autoimmunity and lymphoproliferation. METHODS: We have investigated the presence of CD5+ B cells in a unique cohort of HCV-infected women who were infected with a single inoculum of HCV genotype 1b following immunisation with contaminated anti-D immunoglobulin in 1977. RESULTS: CD5+ B cells are significantly increased in chronic HCV infection (37.66+/-1.92%) as compared with those with resolved infection (25.33+/-1.90%). High levels of CD5+ B cells were associated with the production of rheumatoid factor. The number of peripheral blood CD5+ B cells correlated negatively with histological activity index. CONCLUSIONS: The expansion of this B cell population in patients with active HCV infection may give rise to immune-mediated sequelae associated with HCV infection. This expanded population of CD5+ B cells may protect against the development of progressive liver disease.