Mitochondrial DNA copy number and telomere length in peripheral blood mononuclear cells in comparison with whole blood in three different age groups

•In PBMC mtDNA amount was greater than in WB cells.•In PBMC mtDNA amount increased with age but not in WB cells.•In PBMC telomere length shortens faster than in WB.•In PBMC telomere length had negative correlation with mtDNA copy numbers. There are more and more studies on telomere length (TL) and mitochondrial DNA (mtDNA), and it has been proven that these factors play a significant role in the aging of the immune system thereby it is important to understand how it varies in different cell types for more accurate conclusions. The aim of this study was to look into dynamics of mtDNA amount in conjunction with TL in peripheral blood mononuclear cells (PBMC) during aging in comparison with whole blood (WB) cells. Overall, 53 samples were divided into three age groups: 20–39 year age group, 40–59 year age group and 60–79 year age group. MtDNA amount was determined by qPCR TaqMan, and TL was measured by Southern blotting of terminal restriction fragments (TRFs). PBMC had much higher mtDNA copy number (CN) amount than WB samples. Furthermore, with age, it increased in PBMC, while in WB mtDNA CN count did not change. TL in the elderly group was shorter in PBMC fraction than in WB cells. It also looked like that in PBMC TL shortened faster than in WB. In conclusions, it appears that during the aging process both mtDNA CN and TL were more stable in WB than in PBMC fraction where changes were more drastically pronounced, but more studies using larger sample cohorts should be performed to confirm this observation.