Natural killer cell cytotoxicity and lymphocyte perforin expression in veterans with posttraumatic stress disorder

Objective

To examine the effect of posttraumatic stress disorder (PTSD) on the measures of immune function and the hypothalamic–pituitary–adrenal axis components, and to determine whether additional life stressors affect measured variables.

Methods

We simultaneously examined the natural killer cell cytotoxicity (NKCC), perforin and glucocorticoid receptor (GCR) expression in natural killer (NK) and cytotoxic T (CD8) cells, as well as serum cortisol concentration in a group of Croatian war veterans with chronic, combat-related PTSD (n = 29) and a group of healthy, age-matched men (n = 13). PTSD patients were divided into two subgroups: compensation-seeking (n = 15) and retired or compensation non-seeking (n = 14) subjects. The former includes those involved in the process of getting disability-based army retirement as an additional life stressor.

Results

NKCC was decreased in both PTSD groups when compared to controls. Impairment of NKCC could not be attributed to the perforin expression as perforin was not decreased in comparison to controls. Moreover, the increased level of perforin was recorded in NK cells of retired PTSD subjects. Both PTSD groups shared an increased relative quantity of GCR in lymphocytes, whereas no difference between the groups in the baseline levels of serum cortisol was observed.

Conclusions

Diminished NKCC was not accompanied by perforin insufficiency in PTSD subjects, and other causes should be examined. An additional life stressor does not contribute considerably to either immune or endocrine system related changes.