Data from: Age-related declines in immune response in a wild mammal are unrelated to immune cell telomere length

Senescence has been hypothesised to arise in part from age-related
declines in immune performance, but the patterns and drivers of
within-individual age-related changes in immunity remain virtually
unexplored in natural populations. Here, using a long-term epidemiological
study of wild European badgers (Meles meles), we (i) present evidence of a
within-individual age-related decline in the response of a key
immune-signalling cytokine, Interferon-gamma (IFNγ), to ex vivo lymphocyte
stimulation, and (ii) investigate three putative drivers of individual
variation in the rate of this decline (sex, disease and immune-cell
telomere length; ICTL). That the within-individual rate of age-related
decline markedly exceeded that at the population level suggests that
individuals with weaker IFNγ responses are selectively lost from this
population. IFNγ responses appeared to decrease with the progression of
bovine tuberculosis infection (independent of age) and were weaker among
males than females. However, neither sex nor disease influenced the rate
of age-related decline in IFNγ response. Similarly, while ICTL also
declines with age, variation in ICTL predicted neither among- nor
within-individual variation in IFNy response. Our findings provide
evidence of within-individual age-related declines in immune performance
in a wild mammal and highlight the likely complexity of the mechanisms
that generate them.