Natural Killer Cells Exhibit an Activated Phenotype in Peripheral Blood Mononuclear Cells of Renal Allograft Rejection Recipients: A Preliminary Study.

OBJECTIVES: A growing body of evidence has revealed the role of innate immune cells in transplantation; however, the nature of natural killer cell involvement in rejection is still elusive. Here, we aimed to determine the impact of natural killer cell activities in acute and chronic renal transplant rejection. MATERIALS AND METHODS: This preliminary case-control study included 63 participants: 19 were patients with kidney allograft rejection (8 patients with acute rejection and 11 patients with chronic rejection) and 44 comprised the control group (22 patients who had well-functioning grafts posttransplant and 22 healthy subjects). In addition to natural killer cell frequency, we also measured intracellular interferon-? production and surface expression of CD107a as cytotoxic activity using flow cytometry. RESULTS: We observed a significant increase in CD107a expression (P = .021) in patients with acute rejection versus those with well-functioning grafts. Moreover, production of interferon-? in patients with chronic rejection was significantly increased compared with patients with well-functioning grafts (P = .003). Finally, natural killer cell frequency was decreased in patients with rejection versus control groups; however, this reduction was not statistically significant. CONCLUSIONS: These findings suggest that the increase in natural killer cell cytotoxicity is correlated with rejection in kidney transplant recipients and might be considered as a predictive marker in prevalence of graft rejection.