Cryoglobulinaemic membranoproliferative glomerulonephritis and hepatitis Cvirus infection

Background/Aim. A striking correlation between mixed cryoglobulinaemia and chronic hepatitis C virus infection has recently been described. Since memb rano-proliferative glomerulonephritis is a rare complication of milled cryo globulinaemia, this study was undertaken to determine the prevalence of Hep atitis C virus infection in membrano-proliferative glomerulonephritis. Patients. Eighteen patients, selected among a group of 121 affected by mixe d cryoglobulinaemia, with renal involvement were included in the present st udy. A group of 148 patients affected by renal disease of different aetiolo gy and the general population (6,917 people) were used as control groups. Methods. The presence of anti-hepatitis C virus antibodies was determined b y a commercial kit. The hepatitis C virus genotype was determined according to Okamoto. All patients underwent kidney and bone marrow biopsy while the hepatic biopsy was performed in those showing signs of chronic liver disea se. Results In patients with renal involvement the kidney biopsy showed the pre sence of membrano-proliferative glomerulonephritis Type I in all cases. Chr onic liver disease was present in eleven patients (61%). All patients were positive for serum hepatitis C virus-RNA. Bone marrow biopsy was normal in five cases, while in the others paratrabecular foci of infiltration by smal l lymphocytes were present. In six of these, the massive bone marrow infilt ration by lymphoplasmacytoid lymphocytes suggested the diagnosis of low gra de non-Hodgkin's lymphoma. In the group of patients affected by other chron ic renal disease, the prevalence of hepatitis C virus infection (3.1 %) was not different from that of the general population (3.2%). Conclusions. Hepatitis C virus seems to be the aetiologic agent of mixed cr yoglobulinaemia and, consequently, of membrano-proliferative glomerulonephr itis.