Posttraumatic Natural Killer Cell Decrease is Associated with Septic Complications

There has been paucity in prospective studies investigating trauma-induced changes in the cellular immunity of HIV-seropositive patients and their impact on the clinical outcome after trauma surgery. The role of natural killer (NK) cells especially has not yet been fully elucidated, and the function of this lymphocyte subtype in the immune defense after trauma is still under debate.

This prospective study included patients requiring surgery for abdominal gunshot wounds. A blood specimen was obtained on admission, 48 hours after the index operation and, in case of damage control surgery, 48 hours after the first planned second look operation. The quantity and changes of T-, B- and NK cells were analyzed via flow cytometry to investigate whether these numbers had an impact on the postoperative outcome.

A total of 62 patients were recruited in the analysis of which 38 were HIV-negative and 24 HIV-seropositive. After surgery, HIV-negative patients had a more severe decrease of their CD4+ T cells compared to the HIV-seropositive patients. Trauma resulted in a severe decrease of NK cells irrespective of the HIV-serostatus. Patients with more extensive NK cell drop had a significantly higher postoperative complication rate.

Our data support the association of trauma-induced NK cell decrease with a subsequent significantly higher rate of septic and surgical complications and suggest that these immune cells might play an important role in antibacterial immunity. Strengthening the NK cell function or limiting their decrease in the postoperative course might be of therapeutic value in severely injured trauma patients.