Tolerance to Noninherited Maternal Antigens Allows Successful Second Kidney Transplantation: A Case Report

The 2-way traffic of cells between mother and fetus may introduce noninherited maternal HLA antigens (NIMAs) from the mother to her fetus and expose her to the inherited paternal antigens presented on fetal cells. While contact of maternal immune system with paternal antigens leads to sensitization and development of anti-paternal HLA antibodies, exposure of the fetus to NIMAs can lead to tolerance because of immaturity of the fetal immune system. This state of tolerance is associated with better graft survival from NIMA-mismatched siblings. There are few studies on the effect of tolerance to NIMAs in renal transplant recipients with emphasis on first kidney graft. This reported case combines both effects (sensitization and tolerance) of the same NIMA in a patient who failed the first graft of maternal origin yet demonstrated persistence tolerance toward repeated NIMA mismatches presented on the second sibling donor. To our knowledge, this is the first report of combined effects of the same NIMA encountered by a single patient.