Data from: Social effects on age-related and sex-specific immune cell profiles in a wild mammal

Evidence for age-related changes in innate and adaptive immune responses
is increasing in wild populations. Such changes have been linked to
fitness, and knowledge of the factors driving immune response variation is
important for understanding the evolution of immunity. Age-related changes
in immune profiles may be due to factors such as immune system
development, sex-specific behaviour and responses to environmental
conditions. Social environments may also contribute to variation in
immunological responses, for example, through transmission of pathogens
and stress arising from resource and mate competition. Yet, the impact of
the social environment on age-related changes in immune cell profiles is
currently understudied in the wild. Here, we tested the relationship
between leukocyte cell composition (proportion of neutrophils and
lymphocytes [innate and adaptive immunity, respectively] that were
lymphocytes) and age, sex, and group size in a wild population of European
badgers (Meles meles). We found that the proportion of lymphocytes in
early-life was greater in males in smaller groups compared to larger
groups, but with a faster age-related decline in smaller groups. In
contrast, the proportion of lymphocytes in females was not significantly
related to age or group size. Our results provide evidence of sex-specific
age-related changes in immune cell profiles in a wild mammal, which are
influenced by the social environment.