APHIA Oral Presentation Asia-Pacific Histocompatibility and Immunogenetics Association Meeting 2023

16:20 - 16:30 EPLET and PIRCHE II scores in Northern Territory Renal Transplant Recipients from 2012-2022 from Indigenous and Non-indigenous backgrounds (97059)

Kushan Wathsala Munasinghe 1 , Lucy Sullivan 1 , Tim Emery 1 , Meg Lake 1 , Rory Leahy 1 , Eleni Tsiopelas 1 , Katherine McDonald 1 , Hannah Sullivan 1 , Susan Deayton 1 , Joelene Galea 1 , FIona Bilogrevic 1 , Adrian Fleet 1 , Robert Carroll 1
  1. Lifeblood SATIS Laboratory, North Adelaide, SA, Australia

Human leucocyte antigens (HLA) play crucial role in organ transplantation and poor histocompatibility between donor and recipient results allograft rejection by immune responses. Advancement in HLA typing methods allows for the use of epitope or “eplet” matching algorithms to predict histocompatibility on a molecular level in organ transplantation. 

In this study, we included 144 renal transplant recipients from Northern Territory who were transplanted between 2012- 2022. 44 people identified themselves as having Non-Indigenous backgrounds. Donor and recipient molecular mismatches were calculated by assessing differences in B-cell epitopes (HLAMatchmaker) or T-cell epitopes (PIRCHE II).

The median PIRCHE II score was 318 (range 51-956) and the median HLAMatchmaker mismatches was 66 (range 11-131). The difference between Indigenous and Non-Indigenous median for PIRCHE II was 390 vs 295 (p<0.01) and for EPLET was 72 vs 52 (P<0.01).

For the Indigenous cohort time to rejection and graft survival was no different when people were stratified into quartiles (1,2,3,4) for EPLET and PIRCHE scores. 

When categorised into four groups; classified as being above or below the median value for PIRCHE II and EPLETS the following proportions of recipients developed donor specific antibodies (DSA):

Group 1. high EPLET and high PIRCHE II (n=53): 48% 1 year de novo DSA

Group 2. low EPLET and low PIRCHE II (n=53): 21% 1 year de novo DSA

Group 3. low EPLET and high PIRCHE II (n=19): 14% 1 year de novo DSA

Group 4. high EPLET and low PIRCHE II (n=20): 33% 1 year de novo DSA

In cohorts with high levels of molecular mismatch there is no risk stratification effect with increasing levels of molecular mismatch on time to rejection or medium-term graft survival. However high levels of PIRCHE and EPLET mismatch predict very high prevalence of de novo DSA at one year compared to all other groups (chi2 10.2 p<0.01).

Further research is aimed at the development of cut off scores to predict best transplant survival with lower risk DSA development in this cohort.