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Hepatitis C virus (HCV), which is both a hepatotropic and a lymphotropic virus, has been proposed as a possible causative agent of mixed cryoglobulinaemia. This 'benign' lymphoproliferative disorder can switch over to a malignant B-cell non-Hodgkin's lymphoma (NHL). Therefore HCV infection has been investigated in a series of 50 unselected Italian patients with B-cell NHL. Antibodies against HCV were found in 30% of NHL and HCV viraemia in 32% of cases. HCV-related markers were detected in 34% (17/50) of our NHL patients; this prevalence is particularly significant when compared with HCV seropositivity in Hodgkin's lymphoma (3%) and healthy controls (1.3%).

A striking association between hepatitis C virus (HCV) infection and mixed cryoglobulinemia (MC) has been shown; thus, HCV seems to play an important etiopathogenetic role in this lymphoproliferative disorder. Because HCV is both a hepatotropic and lymphotropic virus, this study aimed to investigate the prevalence of HCV infection of peripheral blood mononuclear cells (PBMCs) in a series of 16 patients with type II (IgMk) MC. Antibodies against HCV were detected by commercially available kits (Second Generation Chiron enzyme-linked immunosorbent assay [ELISA] and recombinant-based immunoblot assay [RIBA]), and the presence of HCV RNA was evaluated in both sera and isolated PBMCs using the polymerase chain reaction technique. A previous exposure to HCV was shown by ELISA and confirmed by RIBA in all cases (100%). Moreover, HCV RNA was present in the sera of 8 of 16 patients (50%), whereas its frequency markedly increased (13 of 16 [81%]) when genomic sequences were detected in peripheral lymphocytes. HCV RNA was never detected in the PBMCs of 20 control subjects. These findings showed that HCV infection, alone or in combination with other factors, may be responsible for the clonal B-cell expansion underlying the systemic manifestations of MC, and may explain the appearance of a malignant non- Hodgkin's lymphoma in some subjects.

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Mixed cryoglobulinemia may be related, at least in part, to the HCV genotype infecting the host.

The effects of interferon-alpha (IFN-alpha) on clinical and serologic manifestations of mixed cryoglobulinemia (MC) were investigated by randomized, crossover-controlled trial in 26 patients. The trial alternated 6 months with and 6 months without IFN-alpha therapy (2 x 10(6) IU daily for a month, then every other day for 5 months). In 22 patients, pretreatment steroid dosage remained unchanged during the study. Six patients dropped out (three because of side effects), whereas another 20 patients experienced a significant improvement of purpura (P < .02) and serum transaminases (P < .005) during IFN-alpha treatment. The presence of clinical improvement was supported by the outcome measurements of several immunologic parameters. In particular, serum cryoglobulins were significantly reduced (P < .04) during IFN- alpha therapy. A rebound phenomenon of clinical and serologic parameters was observed after IFN-alpha discontinuation. In addition, no variations were recorded during 6 months without therapy. Hepatitis C virus (HCV) RNA was detected in 91% (20/22) of our MC patients; in 2/13 cases HCV RNA was no longer detectable in serum samples after IFN- alpha therapy. Thus, IFN-alpha could be considered as treatment for MC in patients with HCV seropositivity.

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EMANUELE MARZO, PIER VITTORIO FOSELLA, GIAMPIERO PASERO. and STEFAN0 BOMBARDIER1The prevalence of antibodies to hepatitis C virus (HCVAb) was investigated in 52 unselected patients with mixed cryoglobulinemia and in 84 patients with other systemic immunologic diseases. HCVAb were detected by an enzyme-linked immunosorbent assay, and their specificity was evaluated by a recombinant-based immunoblot assay. The presence of HBV-related markers was investigated in the same samples. HCVAb were found in 54% of mixed cryoglobulinemia patients, and the finding was confirmed by recombinant-based immunoblot assay in all cases. HCVAb and/or HBV markers were present in 70% of the patients. HCVAb seropositivity was significantly more frequent in mixed cryoglobulinemia patients with biopsy-proven liver involvement (P < 0.01) and with increased serum transaminase levels (P < 0.01). HCVAb were virtually absent in control patients with other immunologic diseases. These results support the notion that viral agents, i.e., HCV and possibly HBV, have a role in the pathogenesis of mixed cryoglobulinemia patients.