Allografts surviving for 26 to 29 years following living-related kidney transplantation: analysis by light microscopy, in situ hybridization for the Y chromosome, and anti-HLA antibodies.

We studied seven patients aged 14 to 40 years who received living-related kidney transplants and had allograft survivals of 26 to 29 years. The blood urea and creatinine were either within normal limits or marginally elevated. Histopathologic examination showed only mild mesangial expansion, interstitial fibrosis, and arteriosclerosis. Immunoperoxidase staining with anti-HLA antibodies or in situ hybridization with a Y chromosome probe showed persistence of donor tubular epithelium and vascular endothelium within the graft. Recipient-derived glomerular cells were seen in one case, and interstitial lymphocytic infiltrates were seen in all cases. A review of the clinicopathologic data available for these cases indicated that both central and peripheral immunologic mechanisms contributed to the maintenance of prolonged graft survival. This extended survival was independent of six antigen matching, down-regulation of donor HLA antigen expression, and ingrowth of host epithelium/endothelium into the allograft.