Circulating lymphocyte subsets, natural killer cell cytotoxicity, and components of hypothalamic-pituitary-adrenal axis in Croatian war veterans with posttraumatic stress disorder: cross-sectional study

To determine peripheral blood lymphocyte subsets--T cells, helper T cells, cytotoxic T cells, B cells, and natural killer cells, natural killer cell cytotoxicity, serum cortisol concentration, and lymphocyte glucocorticoid receptor expression in Croatian combat veterans diagnosed with chronic posttraumatic stress disorder (PTSD); and to examine the relationship between the assessed parameters and the time passed since the traumatic experience. Well-characterized group of 38 PTSD patients was compared to a group of 24 healthy civilians. Simultaneous determination of lymphocyte subsets and the expression of intracellular glucocorticoid receptor was performed using three-color flow cytometry. Natural killer cell cytotoxicity was measured by (51)Cr-release assay and the serum cortisol concentration was determined by radioimmunoassay. We found higher lymphocyte counts in PTSD patients than in healthy controls (2294.7+/-678.0/microL vs 1817.2+/-637.0/microL, P=0.007) and a positive correlation between lymphocyte glucocorticoid receptor expression and the number of years that passed from the traumatic experience (r(s)=0.43, P=0.008). Lymphocyte glucocorticoid receptor expression positively correlated with serum cortisol concentration both in PTSD patients (r=0.46, P=0.006) and healthy controls (r=0.46, P=0.035). This study confirmed that the immune system was affected in the course of chronic PTSD. Our findings also indicated that the hypothalamic-pituitary-adrenal axis profile in PTSD was associated with the duration of the disorder. Due to the lack of power, greater sample sizes are needed to confirm the results of this study.