Quantification of hepatitis C virus-infected peripheral blood mononuclear cells by in situ reverse transcriptase-polymerase chain reaction

Hepatitis C virus (HCV) is known to infect peripheral blood mononuclear cells (PBMC) of patients with chronic hepatitis C, but the proportion of HCV-infected circulating cells is not detectable by conventional reverse transcriptase-polymerase chain reaction (RT-PCR) and the pathogenic significance of HCV lymphotropism is still unclear, Therefore, we have devised an in situ RT-PCR technique using fluorescein-labeled HCV-specific primers revealed by flow cytometry, PBMC were isolated from 28 patients with chronic HCV-related liver disease: of these, 6 had previously received an orthotopic liver transplantation (OLT) and were on immunosuppressive treatment. Fourteen patients (50%) were found positive for HCV genome within PBMC by in situ RT-PCR, the proportion of HCV-infected cells ranging from 0.2% to 8.1%, All 6 OLT patients tested positive, The fluorescent signal, corresponding to the HCV-specific 340-bp amplicon, was confined to part of the cytoplasmic compartment of scattered PBMC, Of these 14 patients, 12 had also negative-strand HCV RNA within PBMC detected by ''tagged'' RT-PCR, We conclude that HCV may infect a significant proportion of PBMC in chronic hepatitis C patients, especially immunosuppressed OLT cases, and that viral replication within PBMC is a common occurrence, Over time, the persistence of HCV-infected immune system cells might interfere with normal immunologic mechanisms and play a role in the pathogenic processes leading to extrahepatic disorders such as mixed cryoglobulinemia and B-cell malignant lymphoma, (C) 1996 by The American Society of Hematology.