Summary. An association between chronic hepatitis C virus (HCV) infection and clonal proliferation of B cells, including B cell lymphoma, has recently been demonstrated. However, the mechanism of malignant transformation is still unknown. It has been shown that B cells from patients with type II mixed cryoglobulinaemia (MC), strongly express the antiapoptotic bcl-2 oncogene product. Therefore, we investigated a possible mechanism of lymphomagenesis, the occurrence of bcl-2 and immunoglobulin gene rearrangement (IgH) in HCV-infected patients. Three groups of patients were studied: (1) 44 patients with HCV and MC (anti-HCV and HCV RNA positive); (2) 59 patients with chronic HCV infection without MC; (3) 50 patients with chronic liver disease (CLD) not related to HCV infection. The t(14;18) translocation (MBR bcl-2±J H ) and IgH rearrangement (FR3/J H ) were detected by polymerase chain reaction (PCR) in peripheral mononuclear cells. bcl-2 translocation was detected in 17/44 (39%), 7/59 (12%) and in none of the patients of groups 1, 2 and 3 respectively (P , 0´01). Monoclonal IgH rearrangement was detected in 15/44 (34%), 5/59 (8´5%) and 2/50 (4%) patients of groups 1, 2 and 3 respectively (P , 0´05). HCV-infected patients had a higher prevalence of monoclonal IgH rearrangement and bcl-2 translocation than patients with CLD of other aetiologies. These data suggest that HCV may play a role in the multistep mechanism of lymphomagenesis by inducing clonal proliferation of B cells and inhibition of apoptosis.

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The mechanism of lymphomagenesis of hepatitis C virus (HCV)–related B-cell lymphoma is unknown. Recently, it has been suggested that HCV may induce B-cell clonal proliferation and t(14;18) translocation in patients chronically infected with the virus. Thus, this study investigated the effect of antiviral treatment on immunoglobulin heavy-chain gene (IgH) rearrangement and t(14;18) translocation in HCV infected patients. Twenty-nine patients with chronic HCV infection were studied in whom IgH rearrangement and/or t(14;18) translocation were previously detected. The IgH rearrangement (FR3/JH) and t(14;18) translocation (MBR bcl2-JH) were detected in peripheral blood mononuclear cells by polymerase chain reaction. Fifteen of 29 patients (8 with IgH rearrangement, 6 with t(14;18) translocation, and 1 with both) were treated with either interferon-α or by combination therapy with interferon and ribavirin for 6 to 12 months. IgH rearrangement became negative in 7 of 9 treated patients compared with only 1 of 8 of nontreated patients (P < .02). The t(14;18) translocation became negative in 6 of 7 treated patients compared with 1 of 6 nontreated patients (P = .03). Disappearance of IgH rearrangement or t(14;18) translocation was strongly associated with virologic response to treatment. Two t(14;18)+patients developed B-cell lymphoma during follow-up. Antiviral treatment appears to be effective in eliminating the clonal proliferation of B cells in patients with chronic HCV infection and may prevent the subsequent development of lymphoma. The mechanism can be related to a direct effect of interferon-α on the proliferating clone or to an indirect effect by eradicating the antigenic stimulus.