*Purpose: A greater degree of HLA mismatch has been previously associated with inferior graft survival in kidney and pancreas transplantation. Pancreas after kidney (PAK) recipients are in a unique situation. On one hand, these recipients have been immunosuppressed for months to years before their pancreas transplant, and on the other hand, they will be exposed to new HLAs from the pancreas donor. How pancreas outcomes among HLA mismatched PAK recipients might differ depending on whether there is a mismatch between pancreas donor and recipient (PD-R) or pancreas donor and kidney donor (PD-KD) are unknown.

*Methods: All primary PAK transplants between 1997 and 2019 at our center were included in this study. Patients were divided into two groups based on the degree of HLA mismatching: low (L-MM) as 0-4 and high (H-MM) as 5-6. We analyzed all (N=73) PAK for PD-R mismatch during the study period, and the subset of PAKs in whom both kidney and pancreas were transplanted at our center for PD-KD mismatch (N=37). Pancreas graft survival and rejection rates were determined over the entire time period.

*Results: The mean interval between kidney and pancreas transplants in the PD-R cohort was 45.2 months. Comparing L-MM (n=39) and H-MM (n=34), we observed no difference in the overall rate of graft loss. 64% of grafts failed (46% death censored, DCGF) in the L-MM group and 62% (26% DCGF) in H-MM (p=0.84). There was also no difference in the overall rate of rejection throughout the whole period [L-MM (33%) vs H-MM (41%)], nor the severity of rejection. We observed a statistically significantly (p<0.01) earlier time to acute pancreas rejection in the H-MM group (6.8 +/- 8.7 mo) vs the L-MM cohort (29.0 +/- 36.2 mo). When stratified according to the type of pancreas transplant induction agent, we observed the overall acute rejection rates to be similar: L-MM(depletional) 33%(6/18), L-MM (IL-2RA) 33% (7/21), H-MM (depletional) 41% (7/17), and H-MM (IL-2RA) 41% (7/17). For the analyses PD-KD subset, 37 recipients had both organs transplanted at our center: 15 were in L-MM and 22 in H-MM. The mean interval between two transplants were 31.2 months. We observed no statistically significant difference in the incidence of pancreas graft loss: 53% grafts failed (27% DCGF) in L-MM and 68 % (41% DCGF) in the H-MM group ( p=0.37). We observed no statistically significant difference in the incidence or severity of rejection. When stratified according to the type of pancreas transplant induction agent, the overall acute rejection rates were similar.

*Conclusions: We did not find a negative impact of HLA mismatch among PAK recipients on either pancreas graft survival or rejection rates.

« Back to 2021 American Transplant Congress