Transplantation of a single kidney per se does not lead to late graft dysfunction

In unraveling the pathogenesis of chronic transplant dysfunction (CTD), non‐alloantigen specific factors, as ischemia/reperfusion and renal mass have been suggested to play a role in the process. The aim of the present study was to investigate the effect of the trans plantation procedure per se on the development of CTD in a syngeneic kidney transplant model in the rat. Kidney transplantation was performed with the BN rat as donor and recipient, the recipient kidneys having been removed. Unilaterally nephrectomized (UNx) and native BN rats served as controls. Renal function was determined monthly (proteinuria and glomerular filtration rate/100 g body weight; GFR). The follow‐up period was until 52 weeks post‐transplantation. Histomorphological analysis of CTD according to the BANFF criteria was carried out. Immunohistochemical staining was performed to identify infiltrating cells (CD4, CD8, and ED1) and the expression of MHC class II and ICAM‐1. Isografts had a minor, constant proteinuria during follow‐up, which did not differ from that of UNx: 27 ± 10 vs. 29 ± 2 mg/ 24 h at week 52. Unilateral nephrectomy led to a significant reduction of the GFR, which was about 80% of that of native rats. The GFR of isografts did not differ from that of UNx rats. Histomorphology of renal isografts was comparable to UNx and native kidneys; some glomerulopathy and tubular atrophy leading to a total BANFF‐score of 2.6 ± 0.5. In native BN kidneys, few CD4+ cells and ED‐1+macrophages (mφ) were found; MHC class II was constitutively expressed on the proximal tubules and ICAM‐1 on the glomeruli and peritubular capillaries. UNx‐kidneys showed a similar pattern. Isografts had significantly more CD4+cells and Mφ, mainly localized in the glomeruli, and a more intense ICAM‐1 expression in the glomeruli and interstitium. Transplantation of one kidney in itself does not lead to CTD.