Age related changes in inflammatory and regulatory subsets within a healthy population are biased by CMV infection and oldest age.

Abstract

Abstract Age-related inflammation is detrimental to the host and plays a key initiator of disease. However, it is unclear how patterns of immune cells and particularly inflammatory and regulatory subsets occur within a healthy population. We investigated peripheral blood markers for immunologic subsets and inflammatory markers using samples collected from a local Blood Bank. 319 subjects between 25–81 years were included that had passed standard collection and infection status criteria. Batches of freshly collected whole blood samples were lysed and immediately processed for flow cytometry using 9-color panels of lymphocyte, myeloid, and platelet markers. Data was normalized by fold change to the young (25–35 yr) group included within batches (7 total) compared to older (36–45, 46–55, 56–64, or 65+ year) age groups. Overall donor age was significantly related to weight, blood pressure, and CMV seropositivity by Spearman’s correlation analyses. We observed few immunologic changes between age groups, except significant differences within the 56–64yr age group. These individuals expressed significantly higher levels of antigen-experienced CD45RO+ CD8 T-cells, regulatory TGF-beta+ CD4 T-cells, and plasma B-cells that correlated with CMV seropositivity. The 56–64 age group also expressed higher levels of non-classical monocytes and platelet monocyte aggregates, both related to inflammation. A lack of changes observed in the highest age group (65+) may be due to selection biases from earlier death and disease. Our data supports that responses to chronic viral infections like CMV may be a major regulator of healthy aging, and also reveals potential biases in recruited populations of older adults.