Immune signatures of Alzheimer’s disease: profiles of neutrophils. (HUM1P.301)

Abstract

Abstract Alzheimer's disease (AD) is the most common form of dementia. Amyloïd plaques accumulation and microbial infections have been proposed as an important components of AD aetiology. Defects in amyloïd-β clearance by monocyte/macrophage/microglia, imply that the immune system may participate in development and progression of AD. Phenotype and functional analysis of polymorphonuclear neutrophils (PMN) in peripheral blood were performed by flow cytometry. Our cohort of patients comprised amnestic Mild Cognitive Impairment (aMCI) (n = 10), mild stage AD (mAD) (n = 10) and healthy elderly controls (n = 10). aMCI patients had memory impairment but no functional disorders. However, these patients have a 50% chance of developing AD within 3 years following the diagnostic. PMN number was unchanged between the three groups. In contrast, the CD177+ population was significantly increased in mAD patients (p < 0.05). Phagocytosis of opsonized bacteria was less in aMCI and AD patients than controls. This observation was associated in aMCI with a decrease in CD33 (siglec 3) and complement receptor for C5A expression. Decreased expression of CD14 (a pattern recognition receptor), CD15 (carbohydrate adhesion molecule) and CD16 (FcγRIII) expression was found in mAD patients. Our results describe for the first time alterations of neutrophils in aMCI patients. PMN analysis may provide a useful tool in early identification of AD patients.