OBJECTIVETo observe the variation and significance of natural killer T (NKT) cells in patients with severe multiple injuries.

METHODSPeripheral blood was drawn from 30 patients with severe multiple injuries and 20 healthy individuals. NKT cells and the subsets of NKT cells were stained and analyzed on fluorescence activated cell sorter (FACS) using Cellquest software. The level of IL-4 and IFN-gamma in blood serum was detected by ELISA.

RESULTSThe proportion of NKT cells was significantly increased. CD4+ NKT cells was increased (t equal to -3.11, P less than 0.01) and CD4+CD8+NKT (double negative NKT, DN NKT) cells decreased in patients with severe multiple injuries compared with healthy controls (t equal to 2.99, P less than 0.01). There was a positive correlation between the proportion of NKT cells and injury severity score (ISS) by Spearman correlation analysis (r equal to 0.70, P less than 0. 01). The level of IFN-gamma was significantly decreased and the level of IL-4 significantly increased in patients with severe multiple injuries.

CONCLUSIONSWe demonstrate that human NKT cells are increased in trauma patients. Most significantly, there is an association between ISS and NKT cells. The increased CD4+NKT cells may contribute to the reduction of Th1 cytokine production and the growth of Th2 cytokine production, leading to the suppression of immunity after injury.