Correlating Changes In Body Weights And Immune System Parameters In Cynomolgus Macaques

By Julie Forget, Amanda Hunerdosse, Robyn Pryor, Megan Templeton, and Cory Chew

As the development of biological and immune-modulating therapeutics continues to rise, there is an increasing need to assess potential toxicity to the immune system, particularly in relation to other toxicity parameters. One standard approach to evaluating the immune system involves adding endpoints such as immunophenotyping of circulating cells. Given the nature of these therapeutics, the cynomolgus macaque is often the preferred test species. However, a recent challenge has emerged: the body weights of cynomolgus macaques available for preclinical studies have decreased due to the high demand for animals in research.

To enhance the assessment of drug-related impacts on the immune system, we established the typical phenotype of circulating immune cells in both young adult and mature, test article-naïve cynomolgus macaques. Blood samples were collected from conscious and restrained animals, and cell populations—including T cells, Helper T cells, Cytotoxic T cells, Total B cells, NK cells, and monocytes—were quantified using the BD FACSCanto II flow cytometer. Linear regression analysis was conducted to assess whether there was any correlation between body weight and circulating immune cell populations. The results showed no correlation between body weight and the relative proportions of immune cell populations in either young or mature animals. Additionally, there were no significant differences in relative cell counts between young adult and mature macaques.