Background: Chronic antibody-mediated rejection (CAMR) of renal allografts has recently been recognized as a defined nosologic entity. The outcome of CAMR is poor; there is no established treatment protocol for this condition. We therefore initiated a pilot study on treatment of CAMR with an antihumoral regimen consisting of high-dose intravenous immunoglobulin (IVIG) and the chimeric anti-CD20 antibody rituximab.
Methods: Six pediatric renal transplant recipients with CAMR received four weekly doses of IVIG (1 g/kg body weight per dose), followed by a single dose of rituximab (375 mg/m2 body surface area) 1 week after the last IVIG infusion. Renal allograft biopsies were evaluated using the Banff '05 classification. Human leukocyte antigen-specific antibodies were detected by panel-reactive lymphocytotoxicity and solid phase ELISA assays.
Results: Median glomerular filtration rate during 6 months before intervention dropped by 25 (range, 11-26) mL/min/1.73 m2 (P<0.05) and increased in response to antihumoral therapy by 21 (-14 to +30) 6 months (P<0.05) and by 19 (-14 to +23) mL/min/1.73 m2 12 months (P=0.063) after start of treatment. Glomerular filtration rate improved or stabilized in 4 patients; the two nonresponders had the highest degree of transplant glomerulopathy, the highest degree of C4d deposition in peritubular capillaries and pronounced interstitial inflammation. The treatment regimen was well tolerated.
Conclusion: This pilot study demonstrates that CAMR in pediatric renal transplant recipients can be treated successfully and safely with a combination of IVIG and rituximab. This observation should encourage more extensive studies to evaluate this new treatment strategy.