A Phase 1, Investigatory Initiated, In-vitro Standardization of B Cell Elispot Assays

Sensitization to HLA antigens is the main barrier to solid organ transplantation. Currently, HLA sensitization is monitored by testing patients' serum against a panel of HLA antigens (whether those will be presented on cell surface or on solid phase matrixes) and calculating the % of positive responses. Such result give indication of the relative breadth of sensitization but not on it "depth" - the relative strength of specific antibodies, nor does it provide any information regarding the memory B cells / plasma cells that can manufacture a specific HLA directed antibody.

This is a single center study to evaluate and optimize the use of in-vitro assay to enumerate B cells producing human leukocyte antigens (HLA)-specific antibodies. The proposed assay is based on principles used for enumeration of specific cytokine producing memory T cells - an ELISPOT assay. The investigators are currently using the T cell ELISPOT assay in our laboratory.

The investigators believe that the proposed assay will provide biologically relevant immune measures that are crucial for the long term outcome of transplantation in highly sensitized patients.

Highly sensitized patients encompass a high risk patient group among transplant recipients. The proposed assay is designed to predict the fate of DSA producing (or capable of producing) memory and plasma cells. Thus, it should allow prediction and early detection of activation of the humoral arm of the immune system, specifically against the donor. This, in turn, may prompt early intervention and preservation of the allograft. Three tubes of blood will be drawn twice, 8-12 weeks apart, during clinic or standard of care dialysis visits following optimization. Subjects undergoing desensitization will have three tubes of blood drawn seven times over the course of two years for the analysis.