The Granule Exocytosis and Fas/FasLigand Pathways at the Time of Transplantation and During Borderline and Acute Rejection of Human Renal Allografts

Cytotoxic lymphocytes induce target cell death by the granule exocytosis mechanism in which perforin and granzyme B induce target cell lysis, and ligation of the Fas-FasLigand, which results in apoptosis. The purpose was to detect the level of activation of cytolytic pathways at the time of renal transplantation and during acute rejection. We investigated 119 biopsies obtained at transplantation from 100 deceased donor allografts and 19 living donor allografts as well as 45 allograft biopsy specimens collected from recipients because of a clinical suspicion of an acute rejection episode. Total RNA was isolated and transcribed to cDNA. To measure mRNA encoding perforin, granzyme B, and FasLigand by real-time quantitative, polymerase chain reaction we used oligonucleotide primers in a LightCycler equipment with cyclophilin B as the housekeeping gene. At the time of transplantation, the transcript expression levels of perforin and granzyme B were the same in the biopsies from deceased and living donors. During acute rejection episodes (n = 10), perforin (P < .01), and granzyme B levels (P < .05) were significantly up-regulated. In cases of suspected rejection (n = 12), both the clinical picture and the effector gene responses were heterogeneous. The FasLigand expression was up-regulated during acute rejection episodes (n = 8) compared with the time of transplantation, but the change was not significant. In conclusion, brain death did not seem to influence the granule exocytosis pathway in the kidney. The cytolytic effector pathways are up-regulated in renal allograft tissue in acute rejection episodes.