Decreased TNF-α and NK activity in obsessive-compulsive disorder

Background: Accumulating evidence points towards the involvement of autoimmune mechanisms in the pathophysiology of some subgroups of obsessive-compulsive disorder (OCD). This study was carried out to investigate whether obsessive-compulsive disorder is associated with altered activity of the immune system, and whether these changes are related to particular clinical characteristics. Methods: Ex vivo production of TNF-α, IL-4, IL-6, IL-10, and IFN-γ in whole blood cultures, and NK-cell activity and peripheral blood NK cell-, monocytes-, T-cell-, and B-cell- percentages were measured in 50 medication-free outpatients with OCD and 25 controls. Results: In OCD patients, we found a significant decrease in production of TNF-α (p < 0.0001) and NK-activity (p = 0.002) in comparison with controls. No significant differences were observed in the other immune variables. Patients with first-degree relatives with OCD had significant lower NK-activity than patients who had no relatives with OCD (p = 0.02), and patients with a childhood onset of OCD had significantly lower number of NK-cells than patients with a late onset (p= 0.003). Conclusions: Changes in TNF-α and NK activity suggest a potential role of altered immune function in the pathophysiology of obsessive-compulsive disorder.