[1611] Diagnostic Utility of C4d Immunohistochemical Staining in Pancreas Allograft Biopsies and Correlation with HLA Donor Specific Antibodies

JJ Liang, RE Domen, T Uemura, A Khan, K Kugler, R Bruggeman, FM Ruggiero, AB Abt, Z Kadry, CS Abendroth. Penn State Milton S Hershey Medical Center, Hershey, PA

Background: The major causes of transplant failure are post-transplant acute cellular and/or antibody-mediated rejection (AMR). AMR of pancreas allografts is poorly understood. C4d is a complement split product generated during antibody-mediated immune response. The C4d staining has been routinely performed in kidney, heart and lung transplant biopsies to aid in diagnosis of AMR; however, its diagnostic utility in AMR of pancreas allografts has not been well defined.
Design: This study includes a total of 28 pancreas allograft biopsies from 12 patients over a two year period. Formalin-fixed, paraffin-embedded sections were immunostained with rabbit polyclonal antibody to C4d (ab36075) (dilution 1:200). C4d staining was graded as positive when strong staining involved more than 50% of interacinar capillaries and as negative when no or focal, weak staining was observed. Positive DSA presence was determined to be ≥1000 Mean Fluoresence Intensity (MFI); negative presence of antibody was <1000 MFI. Each biopsy was correlated with the grade of acute rejection, levels of serum amylase, lipase, presence of HLA DSA, and clinical treatment.
Results: Three of 12 patients (25%) (patients A, B and C;) had HLA DSA during the biopsy period. C4d staining was negative in the biopsy from patient A, who had a moderately high level of HLA anti-A11 DSA (MFI: 3435) and increased amylase and lipase. C4d staining was negative in 5 biopsies from patient B, who had a moderately high level of HLA anti-DQ5 DSA (MFI: range 2257 to 8447) and increased amylase and lipase. By contrast, C4d staining was strongly positive in two of four biopsies from patient C, who had a negative to marginally positive HLA anti-A2 DSA and mildly increased amylase and lipase. All three patients had grade II acute cellular rejection. The remainder of our study patients had no HLA DSA identified and C4d staining was negative. All three allografts are functioning well after a mean followup of 31 months.
Conclusions: 1) Positivity of C4d staining did not appear to be correlated with either HLA DSA or serum amylase/lipase level. 2) C4d IHC staining may not be a sensitive method to detect antibody-mediated rejection in pancreas allograft biopsies and should always be performed in conjunction with HLA antibody screening.
Category: Liver & Pancreas

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 222, Tuesday Afternoon


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