Rejection quantity in kidney transplant recipients is associated with increasing intracellular interleukin-2 in CD8+ T-cells.

Background: CD8+ T-cells and interleukin-2 play an important role during organ rejection in kidney transplant recipients. Numerous studies showed increased interleukin-2 levels during acute rejection. The aim of our study is to show an association between intracellular interleukin-2 in CD8+ T-cells and the incidence of those who underwent organ rejection in kidney transplant recipients.

Methods: 407 transplant recipients were included into this study. The rejection incidence was investigated from the patient records. White blood cells from recipients were separated using a ficoll gradient. The cells were double-gated (CD3+ and CD8+) for the analysis of cellular percentage for intracellular interleukin-2 with a flow cytometer.

Results: The percentage of CD8+ cells with detectable intracellular interleukin-2 was significantly higher in renal transplant recipients with a documented rejection compared to recipients without any history of rejection (9.06±0.50, N=133 vs. 4.28±0.24, N=274, p<0.0001, t-test). Further, there was a significant increase in patients with one (8.02±0.54, N=80, p<0.0001, t-test), two (10.40±1.17, N=33, p<0.0001, t-test) or three (11.82±1.58, N=18, p<0.0001, t-test) rejection events.

Conclusions: Past studies showed, that during acute organ rejection intracellular interleukin-2 is increased in cytotoxic T-cells, supposed to be a marker for this event. We were able to show, that intracellular interleukin-2 in CD8+ T-cells is also increased after organ rejection. Furthermore it seems to depend on the quantity of rejection events. Further studies in recipients with increased intracellular interleukin-2 in cytotoxic CD8+ T-cells and documented history of organ rejection are needed to identify this as a possible risk factor for further rejection events.