Absence of occult hepatitis C virus infection in patients under immunosupressive therapy for oncohematological diseases
Authors: Nicola Coppola, Mariantonietta Pisaturo, Salvatore Guastafierro, Gilda Tonziello, Antonello Sica, Caterina Sagnelli, Maria Giovanna Ferrara, Evangelista Sagnelli
Journal: Hepatology (2011)

We read with interest the review by Welker and Zeuzem1 on occult hepatitis C virus (HCV) infection and replies by Carreño et al.2 and Halfon et al.3 and would like to make our contribution to this topic regarding precisely the role of occult HCV infection in immune-compromised patients. Recently, Barrill et al. found that 45% of 109 anti-HCV–negative hemodialysis patients with abnormal serum aminotranferases had HCV RNA in peripheral blood mononuclear cells (PBMCs),4 but no data are so far available on occult HCV infection in oncohematological patients. We prospectively enrolled 28 consecutive anti-HCV–negative patients with an oncohematological disease who first underwent chemotherapy from April 2006 to November 2007. All patients were screened for hepatitis B surface antigen (HBsAg), anti-HBs (antibody to hepatitis B surface antigen), anti-HBc (antibody to hepatitis B core antigen), and anti-HCV. The diagnosis and treatment of the oncohematological diseases were based on commonly accepted criteria. For each patient, samples of plasma and PBMCs were obtained at enrollment, at months 1 and 3 during chemotherapy, and then every 3 months after treatment discontinuation. The 28 patients were treated with chemotherapy for 4-12 months and observed after its discontinuation for 6-24 months. PBMCs were isolated from 5 mL whole blood by means of Histopaque (Sigma-Aldrich, St. Louis, MO) according to a standard technique and collected in aliquots of 2 × 106 cells. The presence of HCV RNA in plasma and PBMCs of all samples collected during the study was determined as previously reported.5 The detection limit in the plasma samples was around 40 IU/mL. The sensitivity of our method to detect HCV RNA in PBMC samples was assessed using HCV-positive PBMCs diluted in PBMCs obtained from an HCV RNA–negative patient, as described by Halfon et al.6 Briefly, 2 × 106 PBMCs from an HCV RNA–positive patient quantified at 1.8 × 104 IU/2 × 106 PBMCs was sequentially diluted (1:10) in 2 × 106 HCV RNA–negative PBMCs; in these PBMC mixtures, HCV RNA was then quantified by real-time polymerase chain reaction. The lowest detection limit by this method was 18 IU/2 × 106 cells. As a positive control for extraction of RNA from PBMCs, glucose-6-phosphate dehydrogenase (G6PDH) messenger RNA was sought in all PBMC samples collected (LightCycler h-G6PDH Housekeeping Gene Set; Roche Diagnostics, Branchburg, NJ). Table 1 shows the demographic, clinical, biochemical, and serological characteristics observed at the baseline in the 28 patients enrolled (Table 1). The three HBsAg-/HBV DNA–positive patients at the baseline were treated with telbivudine or entecavir. They became HBV DNA–negative within 6 months while still under treatment and remained so throughout the observation; the 16 HBsAg-negative/anti-HBc–positive patients received lamivudine prophylaxis and never showed circulating HBsAg or HBV DNA. No plasma or PBMC sample collected during the study was HCV RNA–positive. All PBMC samples collected were positive for G6PDH messenger RNA. No patient in the present study became positive for HCV RNA in plasma or PBMCs while under chemotherapy for an oncohematological disease. The data from this longitudinal study run counter to the existence of occult HCV infection in patients under strong immunosuppression, who constitute a suitable model of investigation to explore occult HCV infection. In addition, 60.7% of the patients enrolled received rituximab-based chemotherapy, which has been demonstrated as able to increase the HCV replication in anti-HCV–positive patients.7 In conclusion, neither occult HCV infection nor its reactivation under strong immunosuppressive chemotherapy were found in the present study in oncohematological patients who were anti-HCV- and HCV RNA–negative. Our data and those of others6, 8 suggest the nonexistence of occult HCV infection. Nicola Coppola M.D., Ph.D.*, Mariantonietta Pisaturo M.D.*, Salvatore Guastafierro M.D. , Gilda Tonziello M.D.*, Antonello Sica M.D., Ph.D. , Caterina Sagnelli Ph.D.*, Maria Giovanna Ferrara M.D. , Evangelista Sagnelli M.D.* , * Department of Public Medicine, Section of Infectious Diseases, Naples, Italy, Haematology Unit, Second University of Naples, Naples, Italy, Division of Infectious Diseases, Azienda Ospedaliera Sant'Anna e San Sebastiano di Caserta, Caserta, Italy.