Aged Chinese rhesus macaques suffer severe phenotypic T- and B-cell aging accompanied with sex differences.

The elderly usually suffer from increased morbidity and mortality due to infectious diseases, and this process may be attributed to diminishing immune protection with age. This phenomenon is commonly referred to as immunosenescence. However, this theory is still not well defined. Non-human primates serve as a favorable model to facilitate the study in aging of the immune system. Here, we investigated the phenotypic features of T- and B-cell aging in peripheral blood from Chinese rhesus macaques, which included (1) a decrease of CD4/CD8 ratio; (2) a loss of naïve T cells accompanied with elevated proliferation and expansion of effector memory subset; (3) a reduction in B cell numbers and a shift from naïve B cells towards memory phenotype; and (4) increased levels of PD-1 expression in T cells and CD95 expression in B cells. Moreover, an accelerated decline in CD4(+) T cells and naïve T cells was found in male macaques, giving them a more severe immune risk profile. These data indicated that Chinese rhesus macaques share a significant homology with humans in phenotypic aging of adaptive immunity, and may be an appropriate animal model for human aging research.