Association between Cytokine Production and Disease Severity in Alzheimer's Disease

The role of transforming growth factor (TGF)-β1, interferon (IFN)-γ, interleukin (IL)-2, IL-3, and IL-6 in the pathogenesis of Alzheimer’s Disease (AD) has long been reported in literature. In this case-control study, the concentrations of these cytokines in altered T lymphocytes, as well as serum vitamin B12, have been compared in terms of factors such as, age, the clinical course and the patients’ disease risk.40 patients who met the DSM-IV-TR criteria of AD were selected and an age- and gender-matched control group was recruited. The participants’ cognitive performance was measured according to the Mini Mental State Examination (MMSE), the Global Deterioration Scale (GDS) and Clinical Dementia Ratio (CDR). The levels of cytokines were measured in supernatants of lymphocytes culture, using assays of ELISA and atomic absorption.Higher levels of IL-6 and IFN-γ were found more in the altered T lymphocytes of the AD patients rather than in the control individuals. Furthermore, a marginal significant difference was found between the TGF-β levels of the two study groups. Regression analysis of CDR score and cytokines showed the inverse significant correlation between CDR score and IFN-γ levels. Furthermore, the relation between MMSE scores and IFN-γ was significant, meaning that by increasing MMSE score, IFN-γ level was significantly increased.This study suggests that the levels of IL-6 and IFN-γ are significantly increased in altered T lymphocytes of AD patients, as compared to those who are not inflicted with AD, and that they are related to the patient’s age. Also, IFN-γ is related to the severity stage of the AD.