Cell-mediated immunity in combat veterans with post-traumatic stress disorder.

To explore immune function in patients with chronic post-traumatic stress disorder (PTSD). A case-control study using the standardised Cell-mediated Immunity (CMI) Multitest. Cases were 25 Vietnam combat veterans undergoing treatment for clinically diagnosed PTSD. Controls had no diagnosed psychiatric disorders: 28 were civilians and 20 were servicemen who had had South-east Asian postings but no combat experience. The sum score, the number of reactions and the compound scores from the CMI Multitest were assessed as a measure of immune function. Psychometric tests distinguished between cases and controls at a highly significant level (P < 0.001). Veterans with PTSD had enhanced cell-mediated immunity compared with civilians (P = 0.008) and servicemen (P = 0.02). PTSD in combat veterans is associated with enhanced cell-mediated immune responsiveness. This could have wide implications for psychiatry and general medicine.