Selective but attenuated immune cell responses to acute exercise in centenarians

Centenarians represent a model of exceptional longevity and immune resilience. In young adults, acute exercise typically induces rapid immune cell redistribution and provides a useful paradigm to assess immune adaptability. However, immune cell responses to acute exercise in centenarians remain unknown. To characterise acute exercise-induced changes in circulating immune cell populations and phenotypes in centenarians using high-dimensional spectral flow cytometry. Seven centenarians (100–104 years; six women) participated in a randomised crossover study including an acute exercise session (~ 20 min of combined walking, mobility and resistance exercise) and a time-matched seated control condition. Peripheral blood mononuclear cells collected before and after each condition were analysed using spectral flow cytometry and high-dimensional approaches. In this exploratory study, acute exercise was associated with nominally significant condition-by-time interactions in selected immune cell subpopulations, including natural killer (NK) cell subsets and classical monocytes (all nominal p < 0.05). Yet, these findings should be interpreted cautiously given the exploratory nature of the study and the large number of immune outcomes analysed. Furthermore, these effects were modest, occurred alongside baseline differences between study visits, and primarily reflected divergent temporal patterns between conditions rather than pronounced exercise-induced redistribution. No nominally significant changes were observed in phenotypic marker expression or metacluster relative abundance. In centenarians, acute exercise does not induce widespread redistribution or phenotypic changes in circulating immune cells but elicits modest, selective responses, indicating that selected components of immune adaptability may remain detectable even in extreme ageing. These findings support the notion that immune resilience in extreme ageing may be characterised by maintenance of immune homeostasis under physiological stress rather than by pronounced immune reactivity.