Sociodemographic effects on immune cell composition in a free-ranging non-human primate

Abstract

Aging results in declines in immune function and increases in inflammation, which underlie many age-related diseases. These immunosenescent signatures are similar to those seen in individuals exposed to social adversity, who may age more rapidly than those unexposed. Yet, it is unclear how social adversity alters immunity across demographic factors - data that are essential to identify how it might increase aging-related diseases. Here, we investigated how age, sex, and social adversity predicted immune cell proportions in 250 rhesus macaques living in a semi-naturalistic colony. As macaques aged, they exhibited signatures of immunosenescence. Older individuals had signatures of diminished antibody production and adaptive immunity, with declines in CD20+ B cells, CD20+/CD3+ cell ratio, and the CD4+/CD8+ T cell ratio. At all ages, females had higher CD20+/CD3+ and CD4+/CD8+ ratios, indicative of a stronger antibody and adaptive immune response that may facilitate pathogen clearance even with increasing age. Older individuals had signatures of inflammation, with higher proportions of CD3+/CD8+ Cytotoxic T cells, CD16+/CD3- Natural Killer cells, CD3+/CD4+/CD25+ and CD3+/CD8+/CD25+ T regulatory cells, and CD14+/CD16+/HLA-DR+ intermediate monocytes, combined with lower levels of CD14+/CD16-/HLA-DR+ classical monocytes. Notably, we found an interaction between age and social adversity, where low-status individuals had higher proportions of CD3+/CD4+/CD25+ T regulatory cells for their age, compared to higher-status individuals. Together, our study identifies immune cell types that are affected by age and sex in the premier nonhuman primate model of human biology and behavior, and demonstrate a novel link between inflammatory CD4+ T regulatory cells and social adversity.