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 mononuclea r cells (PBMC) of patients with chronic hepatitis C, but the proportio n of HCV-infected circulating cells is not detectable by conventional reverse transcriptase-polymerase chain reaction (RT-PCR) and the patho genic significance of HCV lymphotropism is still unclear, Therefore, w e have devised an in situ RT-PCR technique using fluorescein-labeled H CV-specific primers revealed by flow cytometry, PBMC were isolated fro m 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 po sitive 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 test ed 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 H CV RNA within PBMC detected by ''tagged'' RT-PCR, We conclude that HCV may infect a significant proportion of PBMC in chronic hepatitis C pa tients, especially immunosuppressed OLT cases, and that viral replicat ion within PBMC is a common occurrence, Over time, the persistence of HCV-infected immune system cells might interfere with normal immunolog ic mechanisms and play a role in the pathogenic processes leading to e xtrahepatic disorders such as mixed cryoglobulinemia and B-cell malign ant lymphoma, (C) 1996 by The American Society of Hematology.