Hepatitis C virus but not GB virus C/hepatitis G virus has a role in type II cryoglobulinemia

Objective. Hepatitis C virus (HCV) infection is associated with type II cry oglobulinemia. HCV is specifically concentrated in type II cryoglobulins an d has been implicated in the cutaneous vasculitis associated with the disea se. In contrast to HCV, a role for hepatitis G virus (HGV) in type II cryog lobulinemia has not been defined, although prevalences as high as 43% of HG V infections in type II cryoglobulinemia have also been reported. Methods. We studied 34 patients with type II and 29 patients with type III cryoglobulinemia associated with HCV infection, 6 patients with essential m ixed cryoglobulinemia (EMC; all with type II), 50 hospital control patients , and 125 normal individuals. Serum HCV and HGV RNA were detected by revers e transcription-polymerase chain reaction (RT-PCR). In coinfected sera, HCV and HGV were quantitated by competitive RT-PCR assays. One coinfected pati ent was studied longitudinally for 6 years. Results. Two (5.9%) of 34 patients with HCV-infected type II cryoglobulinem ia, none of 29 patients,vith type III cryoglobulinemia, and none of 6 patie nts with EMC were positive for HGV RNA, for an overall prevalence of 3.0% i n mixed cryoglobulinemia. None of the control populations were positive for HGV. No statistical difference was seen between the prevalence in patients with type II cryoglobulinemia and the other populations studied. In coinfe cted sera, HCV, but not HGV, was concentrated in cryoglobulins, and HCV, bu t not HGV, correlated with cryoglobulinemia in a longitudinal study, Conclusion. There is a low prevalence of coinfection with HGV in patients w ith mixed cryoglobulinemia and HCV infection in the United States. HCV is s electively precipitated by type II cryoglobulins in coinfected sera. HGV in fection does not appear to have a role in mixed cryoglobulinemia.