Posttransplant immune hepatitis in pediatric liver transplant recipients: Incidence and maintenance therapy with azathioprine

Background. Cases of so-called autoimmune hepatitis (AH) have been reported after liver transplantation. Our aim was to evaluate the incidence in a series of 471 pediatric liver transplant recipients. Methods. Between 1984 and 1998, 471 children had orthotopic liver transplantation (OLT). Children are followed up on a regular basis, with full clinical, biochemical, and histologic evaluation at 6 months, 1, 2, 5, 7, and 10 years after OLT. Children with unexplained abnormal liver tests were screened for autoimmune markers (total gamma-globulins, smooth muscle antibodies [SMA], liver kidney microsome antibodies [LKM], antinuclear factor [ANA]). From January of 1998 until December of 1998, autoimmune markers were prospectively searched in all children admitted for regular posttransplant follow-up (n = 118). Results. Eleven of 471 children (2.35%) were found with autoimmune hepatitis, 9 retrospectively and 2 prospectively. None had previous autoimmune liver disease. Patients had a history of steroid-dependent hepatitis. Histology showed variable degree of portal and lobular inflammation, piecemeal necrosis, and bridging collapse. Mean (+/- SDS) aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities at diagnosis were 173 +/- 145 and 196 +/- 157 IU/L, respectively (nl < 32). Median gamma-globulin levels reached 1365 mg/dl versus 931 mg/dl in controls (P <0.05). Nine had ANA (titer 1/80 up to 1/10,000), 1 SMA (1/320), and 2 LKM1 antibodies (1/1280). Patients did not respond to increasing charge of cyclosporine (n=10) or tacrolimus (n=1). Eleven received steroids (prednisolone: 2 mg/kg per day, then tapered) and azathioprine (1.5 to 2.5 mg/kg per day). All patients normalized within 3 months (mean AST/ALT levels of 26 +/-8 and 30 +/-9 IU/L). Three had mild to moderate relapse with increase of ALT thereafter. Gamma-globulins decreased to 1190 mg/dl (ns). Amongst the 116 remaining prospectively evaluated patients, 85 had normal evaluation, despite low titers of autoantibodies in 15 (SMA less than or equal to1/40, ANA 1/80). Thirty-one patients had graft dysfunction, related to well-explained posttransplant causes, among which 7 had similar low levels of autoantibodies. Conclusions. A total of 2.35% of our transplant children present evidence of immune hepatitis after transplantation. Patients do not respond to increasing cyclosporine or tacrolimus levels and require steroid and azathioprine. In view of this specific treatment, systematic screening for "autoimmune" markers is advised in children with liver transplant.