Paired Bone Marrow Aspirations to Assess the Variability of Allo-ELISPOT and Allo-Specificities Assays in Sensitized Renal Allograft Recipients

The aim of this risk protocol is to determine the variability of the AlloElispot and Allospecificities assay.

Our group has developed a number of assays to assess the immune cell population in our transplant population. This has included: 1) the number of donor-specific alloantibody (DSA) secreting bone marrow derived plasma cells (AlloELISPOT assay), 2) the function of DSA-secreting Plasma cells (Allospecificities assay), 3)Culture of plasma cells in human stromal cells to produce specific HLA antibodies and tetanus antibodies, 4) Understand the critical pathways for the survival and function of plasma cells, 5)Characterize the different phenotypes and genotypes of the plasma cell, 6)Phenotype analyses of the immune cell population using flow cytometry and/or mass spectrometry (ie. cytometry by time of flight/CyTOF), 7)Functional assessments of T and B-cells, and 8)T-cell receptor diversity.

These assays were developed over the years and already have provided an important means of testing new therapeutic protocols aimed at controlling DSA production. It is important to note that repeated attempts to isolate PCs from peripheral blood have been unsuccessful (PCs are extremely rare in peripheral blood) and the bone marrow is the only accessible source of PCs.

It is now clear to that we have reached a point that we must validate these assays (coefficient of variation, etc), in order to appropriately evaluate data derived from these assays. Inter-assay variability can be assessed by performing two paired assays in the same patient. This could be done in two ways-paired bone marrow aspirations separated by time or two bone marrow aspirations performed at the same time. We have decided to pursue the latter approach. We will do both marrows either at the time of transplantation or while they are undergoing a surgical procedure. Lymph node retrieval will also be performed at the time for abstraction of immune cells for additional analysis. We believe that this is safe and will be well-tolerated and will provide the data that we need to validate the assays.