PT - JOURNAL ARTICLE AU - Shannon Rausser AU - Caroline Trumpff AU - Marlon A McGill AU - Alex Junker AU - Wei Wang AU - Siu-hong Ho AU - Anika Mitchell AU - Kalpita R Karan AU - Catherine Monk AU - Suzanne C. Segerstrom AU - Rebecca G. Reed AU - Martin Picard TI - Mitochondrial phenotypes in purified human immune cell subtypes and cell mixtures AID - 10.1101/2020.10.16.342923 DP - 2021 Jan 01 TA - bioRxiv PG - 2020.10.16.342923 4099 - http://biorxiv.org/content/early/2021/02/17/2020.10.16.342923.short 4100 - http://biorxiv.org/content/early/2021/02/17/2020.10.16.342923.full AB - Mitochondrial function studies in human leukocytes have mainly focused on peripheral blood mononuclear cells (PBMCs), with the assumption that the immunometabolic properties of different immune cells have a negligible effect on PBMCs. Using a high-throughput mitochondrial phenotyping platform to quantify multiple mitochondrial features among both PBMCs and immunologically-defined immune cell subtypes from the same individuals, we show how mitochondrial activity in PBMCs is confounded by both cell type distributions and contaminating platelets. Then, applying this cell-specific approach in women and men spanning 4 decades of life, we find that mitochondria exhibit specific age- and sex-related differences, including an age-related elevation in mtDNAcn, which are masked or blunted in PBMCs. Our purified cell subtypes data also defines in humans the variation in mitochondrial DNA copy number (mtDNAcn), mitochondrial content (citrate synthase), and respiratory chain enzymatic activities among neutrophils, monocytes, B and T lymphocyte subtypes. Moreover, we validate these cell type differences and define the natural intra-individual variation in mitochondrial function using an intensive repeated-measures study in a single individual, revealing substantial natural variation over time among cell subtypes and PBMCs. Finally, we introduce multivariate mitochondrial phenotypes – mitotypes – that distinguish lymphoid from myeloid cell types, naïve-to-memory lymphocyte states, and moderately differ between women and men, which we propose as potential cell-specific biomarkers for future studies. Together, these findings identify dynamic cell-type specific variation in mitochondrial biology in circulating human leukocytes, providing foundational knowledge to develop interpretable blood-based assays of mitochondrial health.Competing Interest StatementThe authors have declared no competing interest.