Flow Cytometry Crossmatch:A Sensitive Technique for assessment of acute rejection in renal transplantation

THE PRESENCE of anti- donor-specific antibodies before transplantation, detected using a complementdependent lymphocytotoxic test (CDC), is an absolute contraindication to renal transplant; moreover, some authors have observed a high incidence of acute rejection (ARj) episodes1-5 and a decreased graft survival6-9 in kidney transplant recipients with a positive flow cytometric crossmatch (FCXM) before transplantation. FCXM is more advantageous than CDC in that it shows a higher sensitivity in the detection of preformed antibodies10 and allows the simultaneous detection of complement-activating and nonactivating alloantibodies, the class of donor specific antibodies (IgG and/or IgM), and the donor target cells (T and/or B lymphocytes). Nevertheless, pretransplant crossmatching can only give an idea of presensitization. It is not able to identify all patients who will experience rejection following transplantation. Although needle core biopsy represents the most effective tool for diagnosing rejection, many efforts have been made to monitor rejection using less invasive procedures. The aim of this study was to demonstrate that among the many approaches used to monitor rejection in renal transplant recipients FCXM routinely performed after transplantation represents a specific, sensitive, and noninvasive method for monitoring donor specific immune responses. For this purpose FCXM was performed in the first 3 months after transplant on 42 patients who had received cadaveric kidney transplant.