CD8A and post-traumatic stress disorder: PTSD patients and healthy controls did not differ with respect to absolute numbers of lymphocytes (PTSD: 2444,4 ± 144,7 cells/μl; controls: 2719,8 ± 115,6, p = 0.13, ES = -0.11, 95% CI [-0.28, 0.03]), but PTSD patients had significantly higher proportions of cytotoxic T cells (CD3+CD8+) (PTSD: 27.5 ± 1.94%, controls: 20.9 ± 1.52%, p = 0.011; ES = 0.17 [0.05, 0.31]), B (CD3-CD19+) (PTSD: 5.7 ± 0.5%, controls: 2.7 ± 0.3%, p < 0.001; ES = 0.27 [0.18, 0.39] and NK cells (CD3-CD16+CD56+) (PTSD: 15.8 ± 2.5%, controls: 8.5 ± 0.7%, p < 0.01: ES = 0.15 [0.08, 0.22]).