CD21+CD11c+ B cells predicting handgrip strength decline in older adults

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.