Mitochondrial Mass of Naïve T Cells Is Associated with Aerobic Fitness and Energy Expenditure of Active and Inactive Adults, 2022, Alley et al

Abstract

Purpose
Chronic exercise training is known to induce metabolic changes, but whether these adaptations extend to lymphocytes and how this may impact immune function remains largely unknown. This study was conducted to determine the extent to which mitochondrial characteristics of naïve T cells differ according to fitness status and to further examine energy production pathways of cells from aerobically trained and inactive participants.

Methods
Blood was collected from 30 aerobically active (>six hours per week) or inactive (<90 min per week) men and women. Naïve T cell mitochondrial mass, membrane potential, and biogenesis were assessed with flow cytometry. Participants completed a treadmill maximal oxygen consumption (VO2peak) test and wore a physical activity monitor for one week. In a subset of participants, naïve CD8+ T cell activation-induced glycolytic and mitochondrial ATP production was measured.

Results
Active participants exhibited 16.7% more naïve CD8+ T cell mitochondrial mass (p = 0.046), 34% greater daily energy expenditure (p < 0.001), and 39.6% higher relative VO2peak (p < 0.001), along with 33.9% lower relative body fatness (p < 0.001). Among all participants, naïve CD8+ T cell mitochondrial mass was correlated with estimated energy expenditure (r = 0.36, p = 0.048) and VO2peak (r = 0.47, p = 0.009). There were no significant differences in ATP production, mitochondrial biogenesis, or mitochondrial membrane potential between active and inactive groups.

Conclusions
This is the first study to examine the effects of aerobic exercise training status on metabolic parameters within human naïve T cells. Findings suggest that mitochondrial adaptations in certain immune cell types are positively associated with aerobic fitness and energy expenditure. This study provides a foundation for future development of prophylactic and therapeutic interventions targeting specific immune cell subsets to improve the immune response and overall health.

Paywall, https://journals.lww.com/acsm-msse/...l_Mass_of_Na_ve_T_Cells_Is_Associated.12.aspx

 

I wouldn't get too worried about what they say. It bears no relation to immunology as I know it.
If you are physically active the T cells going and out of the blood are likely to be a bit busier just cleaning up mess. Mitochondrial mass is probably a measure of activation. It is quite normal for circulating T cells to have virtually no mitochondrial mass because they are not doing anything. Inactive T cells are mostly just a nucleus and a membrane with receptors.

 

I wouldn't describe less than 90 minutes per week of aerobic activity as particularly inactive. Okay, so members of that group clearly aren't long distance runners or cyclists, but you could be doing two or three sessions a week of interval training within that, which will keep you considerably fitter than what people usually mean by "inactive".