EQUIVALENECE OF ANTIBODY BINDING TO HLA ON BEADS AND CELLS: CRITICAL TESTS IN TRANSPLANATION

Abstract

<p>AMR as a cause of graft rejection has been long recognized and the presence of pre formed antibodies against donor HLA is a risk factor for increased graft rejection. FlowXM is the current clinical gold standard for detecting harmful DSA in the recipients and a positive FlowXM is considered a strong contraindication to transplantation. However, newer techniques such as SAB provide with a highly sensitive and specific method for DSA detection that is unattainable by FlowXM. But due to the intrinsic limitations associated with SAB assays, the clinical relevance of DSA detected on SAB has been highly disputable. Therefore, the overall aim of this study was to investigate the utility of SAB in predicting harmful DSA levels, by establishing a fluorescence range on SAB that correlated to positive FlowXM. This was done by retrospectively testing the highest serum dilutions on FlowPRA SAB that produced positive B or T cell FlowXM from 15 variably sensitized patients. Thus, a very narrow MFI range on SAB was established, for B and T cells separately, that correlated to positive FlowXM. On B cells this correlate ranged from 2780-7772 MFI (Mean MFI =5641), whereas T cell range was 1089-6731 (Mean MFI= 3226). In order to test these ranges for prediction of positive FlowXM, B and T cell FlowXM tests were carried out using various serum/cell combinations. DSA MFI of >3000 on SAB resulted in a significantly higher T cell positive FlowXM (p</p>