Cellular immune phenotypes and worsening scores of frailty-associated parameters over an 18-month period in the very old.

Frailty has been related to inflammaging and certain immune parameters. In previous analyses of participants >80 years of age in the longitudinal BELFRAIL cohort study the main focus was on T-cell phenotypes and the association with CMV-serostatus and survival, finding that a CD4:CD8 ratio >5 was associated with frailty, impaired activities of daily living (ADL), and mortality (but only in women). Here, we phenotyped peripheral blood immune cells via multicolor flow cytometry and correlated these with the dynamics of changes in ADL, geriatric depression score, mini-mental state examination, and short physical performance battery from baseline values over 18 months´ follow-up. We found that higher frequencies of B-cells and late-differentiated CD8+ T-cells at 18 months from baseline were associated with ADL impairment that had worsened over the preceding 18 months. There were no significant associations with monocyte, dendritic cell or NK-cell phenotypes. No associations with the Geriatric Depression Scale GDS, the mini-mental state examination, MMSE or the short physical performance battery SPPB were found. Thus, while these results do not establish causality, they suggest that certain adaptive immune, but not innate immune, parameters are associated with a worsened ADL in the very old.