AGE-RELATED IMMUNE CELL PHENOTYPES IN THE FRAMINGHAM HEART STUDY PARTICIPANTS

Abstract

Abstract Mounting evidence supports a role for the immune system in the pathophysiology of dementia. Alterations in the composition of circulating immune cells is one of the key changes associated with age. However, the role of age and sex on immune cell phenotypes and their contribution to disease pathogenesis remains to be unraveled. We identified a study sample of 996 participants (mean age 62 years, range 40 to 88 years, 52% female, 22% APOE-ϵ4 carriers) from the community-based Framingham Heart Study Offspring cohort who were dementia and stroke free at the seventh examination (1998-2001), the first exam with existing stored peripheral blood mononuclear cells (PBMC). We profiled 132 circulating immune cell phenotypes from cryopreserved PBMCs by flow cytometry using standardized protocols. T cells, B cells, NK cells, and monocytes were reported as percentage of gated lymphocytes or monocytes. All other subsets were reported as percentage of the appropriate parent (e.g. CD4+ and CD8+). We summarized the distributions of each phenotype with age, sex, and APOE-ϵ4 genotype. We also evaluated the differences in percentages of T-cell subtypes including CD4+, and CD8+ T cells and their naïve, effector memory, and central memory subsets across age groups and sex. We observed that for both CD4 and CD8, naïve cells decrease with age, whereas effector/memory cells increase with age with no difference by sex. Future analyses will explore the association between immune cell phenotypes with cognitive test performance and risk of dementia in the context of exposure to cytomegalovirus infection.