Abstract
Purpose Enhanced B-cell presentation of donor alloantigen relative to presentation of HLA-mismatched reference alloantigen is associated with acute cellular rejection (ACR), when expressed as a ratio called the antigen presenting index (API) in an exploratory cohort of liver and intestine transplant (LT, IT) recipients.
Methods To test clinical performance, we measured the API using the previously described 6-hour assay in 84 LT and 54 IT with median age 3.3 years (0.05-23.96). Recipients experiencing ACR within 60 days after testing were termed rejectors.
Results We first confirmed that B-cell uptake and presentation of alloantigen induced and thus reflected the alloresponse of T-helper cells, which were incubated without and with cytochalasin and primaquine to inhibit antigen uptake and presentation, respectively. Transplant recipients included 76 males and 62 females. Rejectors were tested at median 3.6 days before diagnosis. The API was higher among rejectors compared with non-rejectors (2.2 ± 0.2 vs 0.6 ± 0.04, p-value=1.7E-09). In logistic regression and ROC analysis, API ≥ 1.1 achieved sensitivity, specificity, positive and negative predictive values for predicting ACR in 99 training set samples. Corresponding metrics ranged from 80-88% in 32 independent post-transplant samples, and 73-100% in 20 independent pre-transplant samples. In time-to-event analysis, API ≥ 1,1 predicted higher incidence of late DSA after API measurements in LT (p=0.011) and graft loss in IT recipients (p=0.008), compared with recipients with API<1.1, respectively.
Conclusion Enhanced donor antigen presentation by circulating B-cells predicts rejection after liver or intestine transplantation as well as higher incidence of DSA and graft loss late after transplantation
Competing Interest Statement
The antigen presenting test is based on US Patent 10222374 inventors RS and CAA Assignee University of Pittsburgh-of the Commonwealth System of Higher Education Pittsburgh PA and licensed to Plexision Inc. Pittsburgh 15224 in which the University and RS holds equity. CAA is a consultant to licensee without other financial relationships. Disclosed conflicts of interest have been managed in accordance with the University of Pittsburgh policies and procedures. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. All other authors have nothing to disclose.
Alphabetical List of All Abbreviations and Definitions
- (Th)
- T-helper cells
- (Tc)
- T-cytotoxic cells
- (DSA)
- Donor-specific anti-HLA antibodies
- (MHC)
- Major histocompatibility complex
- (CFSE)
- Carboxyfluoresciensuccinimidylester
- (PBL)
- Peripheral blood lymphocytes
- (API)
- Antigen presenting index
- (LR)
- Logistic regression
- (ROC)
- Receiver-operating-characteristic
- (FKWB)
- Tacrolimus whole blood concentration
- (CI)
- Confidence intervals
- (Cyto D)
- Cytochalasin D
- (Prima)
- Primaquine
- (AUC)
- Area under the receiver operating characteristic curve
- (Tx)
- Transplantation
- (PPV)
- Predictive Value
- (NPV)
- Negative Predictive Value
- (LT)
- Liver Transplantation
- (IT)
- Intestine Transplantation
