Post-Traumatic Stress Disorder (PTSD) is a clinical syndrome characterized by prominent affective symptoms and by a 'hyperactive' sympathetic nervous system. A high percentage of combat veterans, survivors of catastrophic events experience symptoms of PTSD. PTSD is accompanied by a number of specific and non-specific ''somatic'' pathologies, such as immune and physical complaints/chronic pain. The present study emphasizes the important role of the immune reactions in the pathogenesis of PTSD.

Our study was aimed at the determination of the total hemolytic activity of the complement by the classical and alternative pathways and the activities of individual complement components, C3 and C4 in the blood serum of patients with PTSD and healthy volunteers. A hemolytic assay was based on the standard 50% complement hemolysis test for the classical and alternative pathways.

There was detected a significant increase in the mean values of the total hemolytic activity of the complement activation by the classical pathway as well as C3 and C4 hemolytic activities and significant decrease in the mean values of the total hemolytic activity of the complement activation by the alternative pathway in patients of PTSD compared to healthy subjects.

Our results emphasize the important role of complement classical pathway activation in pathogenesis of PTSD and our data has raised a number of important questions relevant to PTSD pathomechanisms, especially from the point of view of immunity.