P126 : A CASE STUDY: ACUTE HUMORAL REJECTION DUE TO ANTI-HLA DP ANTIBODIES IN A RENAL TRANSPLANT RECIPIENT

Abstract

We report the case of a highly sensitized 37 year old male who suffered an acute humoral rejection due to donor specific anti-HLA DP (DP) following a second kidney transplant. A previous living donor kidney graft failed in 2005 due to noncompliance with immunosuppression and he returned to hemodialysis. Past history included two blood transfusions. On evaluation for retransplant in 2010, his cPRA using microarray single antigen beads (One Lambda) was 100% including anti-DP1 (MFI 4221). On 2/17/14, he received a deceased donor kidney (KDPI 17%). T and B cell crossmatches by CDC-AHG/CDC long incubation and by the rosette method (Life Technologies) were compatible. There were no donor specific antibodies (DSA) to HLA A B Cw DR or DQ. DP typing of deceased donors was not performed. Retrospective DP typing indicated that the donor was DP1. The clinical staff was advised. He received Thymoglobulin induction and was placed on Mycophenolate Mofetil (MMF), prednisone and Tacrolimus. By post op day (POD) 10, his creatinine decreased to 1.6 mg/dL. On POD 18, his creatinine increased to 2.5 mg/dL. Biopsy results showed acute glomerulitis and acute tubular necrosis. C4d staining was positive. A biopsy day serum showed anti-DP1 (MFI 7627) by microarray single antigen beads and (MFI 26038) using the C1q binding assay (One Lambda). C1q testing of archived crossmatch serum did not show anti-DP1. After treatment with plasmapheresis and 1 g/kg IVIg, his creatinine stabilized at 1.8–2 mg/dL. He is currently maintained on MMF, Tacrolimus and prednisone. A survey of 1069 renal transplant candidates revealed that 13% had DP antibodies. Two of three transplanted patients with DP antibodies retrospectively determined to be DSA had humoral rejections. Another patient with no pre-transplant DSA received a crossmatch compatible kidney and had a rejection due to de novo anti-DP. These 3 cases were regrafts. Our experience is consistent with recent literature. With increasing evidence that DP antibodies can cause graft rejection and with technology available to perform HLA DP typing and antibody monitoring, the transplant community should take action to recognize the potential risk of DP antibodies in renal transplant, require DP typing of all donors prior to transplant and consider incompatible donor DP antigens unacceptable for regrafts.