Defective T-cell Proliferation and IL-2 Production in a Subgroup of Patients with Coronary Artery Disease

Atherosclerosis is a chronic inflammatory disease of the arterial wall characterized by innate and adaptive immune responses to a variety of microbial and self-antigens. Given the crucial role of adaptive immunity in the pathogenesis of atherosclerosis, this study was performed to investigate the proliferative response of peripheral blood mononuclear cells (PBMC) and interleukin (IL)-2 production in patients with coronary artery disease (CAD). In this study, 25 patients with chronic stable CAD and 25 healthy individuals were investigated. The PBMCs were separated and stimulated with phytohaemagglutinin (PHA). MTT assay was performed to measure cell viability and proliferation. IL-2 concentrations in cell culture supernatants were determined by Enzyme-Linked Immunosorbent Assay. PHA-stimulated cells revealed a significantly increased optical density (OD) in both groups of patients (p=0.004) and controls (p<0.001). However, the patient group showed a significantly lower Stimulation index (SI) (p=0.001). Upon in vitro stimulation with PHA, IL-2 levels were significantly increased in both groups of patients and controls (p<0.001). However, IL-2 concentrations were significantly lower in the patient group (p=0.018). Six patients showed defective IL-2 production, whereas similar finding was not observed in the normal control subjects (p=0.022). PBMCs from patients with coronary artery disease showed defective PHA-induced mitogenesis and IL-2 production. Considering the autoimmune nature of atherosclerosis, decreased IL-2 production may potentially enhance the atherogenic process, leading to spontaneous activation of autoreactive T lymphocytes.