Hepatitis C virus (HCV) and lymphomagenesis.
Hepatitis C virus (HCV) is the major cause for non-A, non-B hepatitis. Most HCV-infected individuals do not clear the virus resulting in a chronic infection that may potentially lead to liver cirrhosis and hepatocellular carcinoma. In addition to hepatic manifestations, HCV infection is associated with B cell lymphoproliferative disorders, including mixed cryoglobulinemia, usually a benign condition, and overt B cell lymphoma. A direct role of HCV infection in the genesis of these B cell lymphoproliferative disorders has been suggested initially by epidemiological studies and is supported by recent studies, which analyzed the monoclonal B cells that proliferate in these disorders. How HCV induces B cell lymphoproliferative disorders is still unclear, it is probably not due to direct change of phenotype in B cells after viral infection, but may be due to an HCV-antigen driven process. Support for this hypothesis comes from the analysis of monoclonal B cells found in these disorders, which use a restricted repertoire of immunoglobulin variable region genes that are similar to those used by B cells that secrete anti-HCV antibodies. The fact that monoclonal IgM is resolved in HCV-infected patients who responded to anti-viral treatment supports the linkage between antigen persistence and B cell proliferation. Finally, the linkage between benign B cell proliferation and overt lymphoma is supported by the identification of a pre-malignant B cell clone that subsequently converted to an overt B cell lymphoma. The molecular basis for viral induced B cell proliferation is still unknown. One possibility is that HCV stimulates the proliferation of monoclonal B cells via their HCV-specific B cell receptor (BCR) on the cell surface. Binding of the HCVenvelope proteins to a cellular ligand, CD81, may also enhance this antigen-driven process. A recent report on regression of splenic marginal zone lymphoma after anti-viral treatment with interferon and ribavirin has significantly strengthened the cause-effect relationship between HCV infection and lymphoma. Further studies should determine whether BCRs expressed on HCV-associated lymphomas, particularly those that regress in response to anti-viral therapy, bind HCV antigens that stimulate their proliferation.
Weng
Wen-Kai
WK
Department of Medicine, Division of Oncology, CCSR 1105a, Stanford University School of Medicine, Stanford, CA 94305, USA.
Levy
Shoshana
S
D001402:B-Lymphocytes / Q000821:virology; D016174:Hepacivirus / Q000502:physiology*; D006526:Hepatitis C / Q000821:virology*; D006801:Humans; D008213:Lymphocyte Activation; D016393:Lymphoma, B-Cell / Q000821:virology*