Clear Evidence of the Existence of Healthy Carriers of Hepatitis C Virus Among Renal Transplant Recipients

The fact that there may be healthy carriers of hepatitis C virus (HCV) in the general population has not yet been fully established, although it has been suggested in a few reports (1-4). However, it has never been described in immunocompromised hosts. This letter reports strong evidence of the definite existence of an HCV healthy carrier status among renal transplant recipients (RTxR). We studied 399 patients who received transplants between August 1984 and December 1991 and who also received cyclosporine as the main immunosuppressor, together with low-dose steroids and/or low-dose azathioprine. HCV antibodies were detected by specific second-generation ELISA, then confirmed by RIBA II. One hundred and five patients were already HCV positive at the time of transplantation and have remained so. Twelve patients exhibited seroconversion during transplantation as a result of either blood transfusion (BT) or graft contamination. The prevalence of HCV-infected recipients was 117/399 (29.3%)(5). Of these 117 HCV-positive patients, 11 were also infected with hepatitis B virus (HBV) (HCV/HBV co-infection) and 106 transplant recipients were infected with HCV only. The overall results of this positive population were as follows: (1) only 26 patients exhibited either continually or occasionally elevated alanine aminotransferase (ALT) levels (25%), and (2) 62 patients have already accepted liver biopsy as a systematic procedure (58%), which disclosed chronic active hepatitis (CAH) in 26 of them (42%), portal lesions (inflammation and/or fibrosis) in 14 (22%), normal liver in 12 (20%), acute hepatitis in 5 (8%), and various lesions in 5 (8%). In the CAH subgroup, the mean Knodell score was only 6.14 (range, 3-12) and only three patients had stage 4 fibrosis(cirrhosis); only 12 patients were symptomatic (46%). No liver carcinoma was observed. The 12 RTxR with normal liver pathology were further selected as HCV healthy carriers because they met all of the following criteria: (1) persistent active HCV infection, demonstrated by the presence of HCV RNA in successive serum samples tested by standard reverse transcriptase-nested polymerase chain reaction (PCR) with primers chosen in the highly conserved 5′ noncoding region; (2) normal ALT levels in successive serum samples(<1.5 times the upper limit of the normal range), without any clinical signs of liver disease; and (3) normal liver biopsy performed after at least a 2-year follow-up. There were eight male and four female RTxR patients. The original kidney disease was chronic glomerulonephritis in six patients, congenital uropathy in two, pyelonephritis in two, and unknown in two. All patients were treated using chronic hemodialysis for a mean period of 36.2 months before transplantation (range, 11-60 months); mean age at the time of transplantation was 42.3 years (range, 16-65 years). All patients received BT before transplantation. There were nine cadaveric donors and three living donors. Eight recipients were Italian and four were French; none was co-infected with HBV or HIV ½. Immunosuppressive treatment at the time of liver biopsy was cyclosporine in all patients, azathioprine in 10 (mean dose =45 mg/day), and prednisone in nine (mean dose =6.4 mg/day). All patients but one (male, Italian, living donor, 38 years old, 26-month dialysis) were positive for antibodies to HCV and for HCV RNA in serum at the time of transplantation and remained so throughout the follow-up period. They were presumably contaminated during the first year of dialysis (BT or unknown). Genotyping was performed on PCR products by reverse hybridization with specific probes (Innolipa kit, Ingen Inc.) and produced the following results, according to Simmonds's classification (6): seven were infected with genotype 1b, three with 3a, and one with 4a. Liver biopsy was performed at a mean follow-up time of 60.8 months (range, 24-96 months) after transplantation. Specimens were analyzed by a liver pathologist according to a blind protocol. All patients had a normal liver; scoring on the Knodell scale was 0 or 1 (minimal unspecific change in the portal space). At the time of biopsy, specific HCV RNA sequences were detected in the serum of 11 patients at the first step of nested PCR (outer primers) and in the last case at the second step (inner primers). Quantitative PCR, performed using a commercially available kit (HCV Amplicor monitor; Roche Inc., Basel, Switzerland) (7), during the same period revealed a low genomic replication rate (mean=31×104; range, 1.6-67) per milliliter of serum. IgM antibodies to core HCV antigens(8) were tested by ELISA (Abbott Laboratories) and the tests were positive in five patients at the time of biopsy. In addition, total RNA from liver biopsy material was extracted as described previously(9) and screened for specific HCV RNA sequences with the reverse transcriptase-nested PCR technique used for serum samples: HCV RNA was detected in the liver of nine of the 11 patients tested (six outer, three inner). At the last follow-up visit (mean, 71.9 months; range, 36-108 month) all grafts were still functional, with good renal function in seven (mean serum creatinine [SC] level=129 μmol/L), fair renal function in two (SC=229μmol/L), and poor renal function due to chronic rejection in three (SC=395μmol/L). We have thus clearly identified a small group of RTxR with HCV RNA present in their blood (active infection), but low replication activity according to quantitative PCR, and no liver disease, as shown by normal ALT levels during a mean 6-year monitoring period and by normal liver biopsy results after a mean follow-up period of 5 years after transplantation, presumably after a mean 8 years since viral contamination (time of dialysis added). These patients currently appear to tolerate to their virus strain on a long-term basis and we believe they deserve to be designated as HCV healthy carriers. This finding is not explained by any particular variant with the most frequent genotype being 1b, which is known to be highly inductive of chronic active hepatitis with a weaker response to α-interferon treatment in the general population. Long-term immunosuppression in these 12 patients is no different from that of other recipients, and we previously shown (5) that kidney graft survival is similar in HCV-positive and -negative groups. This is in contrast with other immunodeficiencies in which the course of HCV infection is rapidly progressive (10). At least immunosuppression had no deleterious effect on HCV liver infection. Furthermore, in our 106 long-term immunosuppressed, HCV-infected RTxR, the prevalence of CAH, cirrhosis, and liver cancer is 42%, 3%, and 0%, respectively. These data should be compared with those usually proposed(11) for the general population, i.e., 60% for CAH, 18% for cirrhosis (30% of CAH), and 2-3% for cancer (10-15% of cirrhosis), although these data refer to a longer follow-up period (15-20 years). Our results are not consistent with any deleterious effect of low-dose chronic immunosuppression. The high proportion of HLA-DR5 seropositive patients (8/12 [57%]) relative to appropriate controls (34/124 [27%]; X2=7.90; P=0.005; Pc=NS) may suggest an involvement of genetic factors in this tolerance to HCV(12), but this point needs further confirmation. In conclusion, we have confirmed the HCV healthy carrier status following renal transplantation with cyclosporine as the main therapy. This status may apply to around 20% of chronically HCV-infected recipients. Full explanation for this tolerance is still lacking. Long-term surveillance of these patients will be necessary to appreciate whether this tolerance is indefinite or merely corresponds to a delay in liver damage occurrence. Nevertheless, this finding supports our current policy to continue to perform transplantations in HCV-infected patients, unless liver cirrhosis has been detected at a prior liver biopsy. J. Haem1-3 P. Berthoux2, 4 J. F. Mosnier2, 5 F. Grattard6 S. Cecillon2, 4 B. Pozzetto6 E. Alamartine2, 4 F. Berthoux2, 4 Departments of Nephrology, Hepatology, Pathology, and Virology; University Hospital of Saint-Etienne; Hôpital Nord; 42055 Saint-Etienne, Cedex 2, France; Groupe de Recherces sur les Glomérulonéphrites et la; Transplantation Rénale EZ no. 773; Faculté de Médecine Jacques Lisfrance; 42023 Saint-Etienne Cedex 2, France