ABSTRACT
Up to 30% of patients waiting for a renal allograft are immunized, that is, possess in their sera antibodies directed against allogeneic human leukocyte antigen (HLA) molecules. The presence of antibodies of the immunoglobulin G (IgG) isotype, directed against HLA class I molecules borne by the graft, is very strongly correlated with episodes of severe acute rejection and graft loss1. The existence of these antibodies is demonstrated by a technique called ‘cross-match’, in which the serum of the recipient is incubated with lymphocytes from the donor and the potential binding revealed, either through cytotoxicity with rabbit complement or through flow cytometry using a secondary antibody. The positivity of a classic cytotoxic T-cell IgG cross-match is an absolute contraindication to transplantation2. Transplantation of such patients is thus hampered by the need to find a compatible organ which does not harbor any of the HLA molecules recognized by the patient’s antibodies, so the waiting time of these patients extends frequently to more than 3 years3. Moreover, once grafted, these patients are at risk, with more rejections and a lower graft survival than in naive patients.
