Abstract
Using a high-throughput mitochondrial phenotyping platform to quantify multiple mitochondrial features among immunologically-defined immune cell subtypes, we define the natural variation in mitochondrial content, mitochondrial DNA copy number (mtDNAcn), and respiratory chain enzymatic activities in human neutrophils, monocytes, B cells, naïve and memory T lymphocyte subtypes. In mixed peripheral blood mononuclear cells (PBMCs) from the same individuals, we show how mitochondrial measures are confounded by both cell type distributions and contaminating platelets. Cell subtype-specific measures among women and men spanning 4 decades of life indicates age- and sex-related differences, including an age-related elevation in mitochondrial DNA copy number (mtDNAcn), which are masked or blunted in mixed PBMCs. Finally, a proof-of-concept, repeated-measures study in a single individual validates cell type differences and also reveals week-to-week changes in mitochondrial activities. Together, these mitochondrial phenotype data in defined circulating human leukocytes sub-populations provide foundational knowledge to develop interpretable blood-based assays of mitochondrial health.
Competing Interest Statement
The authors have declared no competing interest.