VH1-69 gene is preferentially used by hepatitis C virus-associated B cell lymphomas and by normal B cells responding to the E2 viral antigen

Hepatitis C virus (HCV)-associated B cell lymphomas were previously shown to express a restricted repertoire of immunoglobulin V-H and V-L genes, V(H)1-69 and V(K)A27, respectively. Although this suggests a role for antigen selection in the pathogenesis of these lymphomas, the driving antigen involved in the clonal expansion has not been identified. B cell response to a viral antigen, the HCV envelope glycoprotein 2 (E2), was analyzed in an asymptomatic HCV-infected patient. Single B cells, immortalized as hybridomas and selected for binding E2, were analyzed for their V gene usage. Sequences of these V region genes demonstrated that each hybridoma expressed unique V-H and V-L genes. Remarkably, these anti-E2 hybridomas preferentially used the V(H)1-69 gene. Analysis of replacement to silent mutation ratios indicated that the genes underwent somatic mutation and antigenic selection. In a separate report, human anti-E2 antibodies were also shown to express the same V-H gene. These data strengthen the hypothesis that the HCV-associated lymphomas are derived from clonally expanded B cells stimulated by HCV. (C) 2001 by The American Society of Hematology.