HISTOCOMPATIBILITY TESTING PREDICTS ACUTE RENAL ALLOGRAFT REJECTION RISK IN EARLY CORTICOSTEROID CESSATION (ECS) REGIMENS

Abstract

O140 Aims: Little data exists regarding the ability of standard histocompatibility testing to predict acute rejection (AR) in kidney transplant (Tx) recipients receiving corticosteroid (CS)-free immunosuppression (IS). Moreover, no data exists regarding the ability of newer techniques (flow cytometric PRA testing with Class I and II MHC beads) to predict AR risk. The purpose of the present study was to evaluate old and new histocompatibility techniques in predicting AR risk in kidney Tx recipients who undergo early (<7 day) CS withdrawal (WD). Methods: 234 patients (pts) were entered in 6 IRB-approved early CSWD regimens. Histocompatibility testing included: serologic PRA, flow cytometic PRA testing by Class I and Class II MHC beads, and B cell crossmatching. The flow B cell crossmatch assay was optimized by pronase treatment of cells. Influence of individual tests was examined using logistic regression analysis. Results: Results are presented in Table I.FigureLogistic Regression Analysis Cadaveric and LURD Tx recipients were at signficantly higher risk of AR. Accordingly, HLA AB and DR locus mismatching was associated with increased AR risk, with DR mismatching conferring a greater risk. Serologic, but not flow cytometic PRA analysis predicted AR risk, with current PRA testing the stronger predictor (1.7% increase in AR risk for each 1% increase in PRA). Finally, pronase-optimized flow cytometric B cell crossmatch also predicted AR risk. Conclusions: 1)Histocompatibility testing can predict AR risk, 2) HLA AB and DR mismatching are associated with increased AR risk, 3) serologic PRA, but not flow cytometric PRA testing predicted AR risk, 4) current PRA provides a stronger predictor or AR risk than peak PRA, and 5) pronase-optimized flow cytometric B cell crossmatching may provide an additional means for identifying recipients for high risk of AR. These data support the use of histocompatibility testing as a means for predicting AR risk in renal transplant pts who receive early CSWD.