Abstract

Background: Preserving physical function is central to healthy aging, and declines in handgrip strength are strong predictors of frailty, disability, and mortality. Although immunosenescence has been implicated in age-related functional decline, the contribution of specific B-cell subsets to longitudinal changes in muscle strength remains poorly understood. Objective: To examine whether baseline B-cell phenotypes are associated with 1-year changes in handgrip strength in community-dwelling older adults. Methods: Sixty-two adults aged ≥60 years from the Magallanes Region, Chile, underwent baseline and 1-year follow-up assessments of handgrip strength and body composition. Peripheral B-cell subsets were characterized by flow cytometry, identifying CD45+CD19+ lymphocytes and classifying subsets according to CD21 and CD11c expression. Associations between baseline B-cell subsets and 1-year change in handgrip strength were evaluated using robust linear regression adjusted for age, sex, and change in muscle mass. Results: Participants showed a significant 1-year decline in handgrip strength (mean change: -2.02 kg), whereas muscle mass remained stable. Higher baseline frequencies of CD19+CD21+CD11c+ B cells were independently associated with greater decline in handgrip strength over 12 months (βstd = -0.31, CI95% [-0.60, -0.03], p = 0.031). No other B-cell subset was associated with changes in handgrip strength or muscle mass. Conclusion: Baseline levels of CD19+CD21+CD11c+ B cells were associated with a subsequent decline in handgrip strength in community-dwelling older adults, independent of change in muscle mass. These findings support a potential link between B-cell phenotypes and functional decline, warranting further investigation in larger cohorts.