Pancreas Biopsy allows accurate diagnosis of rejection of the pancreas transplant. Our group has shown previously that pancreas biopsy is safe, has a high diagnostic yield and, in cases of SPK, shows up to 40% discordance in rejection with a concurrent kidney biopsy.

Aim: To study what the incidence of Luminex DSA pre and post-transplant is, and their association with rejection in patients biopsied for potential pancreas rejection.

Patients and methods: 37 pancreas biopsies performed were interpreted by a single pathologist. All biopsies were stained for C4d. Recipients had their pretransplant sera investigated for the presence of antibodies to HLA by Luminex LABScreen Mixed. Mixed positive sera were tested by LABScreen Single Antigen for determination of HLA specificity. LABScreen Single Antigen was used to test for DSA during each rejection episode.

Results: 37 biopsies were performed on 26 patients out of the 108 pancreas transplants performed in the centre.

14 biopsies showed ACR whereas 3 biopsies showed AMR (1 mixed). The biopsies that showed no rejection were performed at a median of 321 days post transplant. 9 of those patients (34.6%) had positive pretransplant DSA whereas 13 (50%) had positive DSA at the time of Biopsy. 15.4% had Luminex DSA with MFI over 2000 pre compared to 30.8% at the time of biopsy. These figures compare with our kidney only transplant population pretransplant DSA of 24.8% (p=0.18), out of which 8% had MFI over 2000. There was no difference in the percentage of patients expressing pretransplant DSA between those who had biopsy proven rejection and those that did not (but still had a biopsy). 57% of those with rejection had positive DSA posttransplant compared to 41% of those without rejection. Interestingly rejection was the same or less common in patients with MFI over 2000 at the time of transplant or the time of biopsy compared to those without DSA. Only 1 case out of 3 with AMR had preformed DSA, and although they all expressed DSA at the time of rejection in 1 of them was less than 2000 MFI.

Conclusion: Low-level Luminex DSA pretransplant are common in the pancreas transplant population. They do not seem to be associated with frequency of rejection. A pretransplant DSA MFI level of 2000 in the absence of cytotoxic antibodies does not seem to be associated with more frequent rejection diagnosis at the time of a pancreas Biopsy.

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