ACT 2024 -- Regulatory T cells (Tregs) are widely recognized as a critical component of the immune system and an increasing number of studies are identifying new roles these cells play in immune tolerance and the success of clinical immunotherapy treatment. Due to the importance of accurately measuring Tregs in the modern drug development landscape, greater scrutiny is being placed on the methods used to identify them. Immunophenotyping via flow cytometry is a widely recognized technique for analyzing Tregs in whole blood from both preclinical and clinical samples; however, the preferred set of markers for identifying Tregs is debated. Here, our laboratory examined three widely used Treg phenotypes (CD25+FoxP3+, CD25+CD127- and CD25+FoxP3+CD127-) in parallel using whole blood from up to 32 cynomolgus macaques, a common nonhuman primate model in toxicological safety assessment studies. 

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