Abstract
OBJECTIVE: The study investigated the response of immune cells, particularly natural killer (NK) cells and innate lymphoid cells (ILCs), to acute exercise in adolescents and young adults (AYAs) undergoing cancer treatment, to lower their treatment burden and evaluate the value of exercise in this vulnerable cohort. METHODS: An AYA cancer patient group (PG) (n = 20, 25 ± 7 years old) and an age-matched healthy control group (HG) (n = 20, 27 ± 5 years old) completed a twenty-minute high intensity interval training (HIIT) on a bicycle ergometer. Blood was taken at three timepoints during the intervention. Once immediately before (T0), once immediately after the intervention (T1), and after one-hour of recovery (T2). NK cells, ILCs, respectively their subpopulations, were determined by flow cytometry. RESULTS: Total NK cells (PG: p = 0.023; HG: p = 0.004), CD56(dim)NK cells (PG: p = 0.035; HG: p = 0.004), total ILCs (PG: p < 0.001; HG: p < 0.001), ILC1-like (PG: p = 0.001; HG: p = 0.004), ILC2 (PG: p = 0.006; HG: p = 0.003) and innate lymphoid cell precursors (ILCPs) (PG: p = 0.009; HG: p = 0.002) increased significantly from T0 to T1. CD56(bright)NK cells (HG: p = 0.011) increased significantly only in the HG. From T1 to T2 total NK cells (PG: p < 0.001; HG: p < 0.001), CD56(dim)NK cells (PG: p < 0.001; HG: p < 0.001), CD56(bright)NK cells (PG: p < 0.001; HG: p < 0.001), ILC2 (PG: p = 0.035; HG: p = 0.007) and ILCPs (PG: p = 0.006; HG: p = 0.003) decreased significantly. ILC1-like maintained their elevated cell count plateau during the recovery phase. No significant differences were found for NKp44(+)ILC3 and for inter-group comparisons regarding the percentage changes of cell counts from T0 to T1 or T1 to T2. Younger age and higher heart rates (in percentage of age-predicted maximal heart rate) during the intervention were associated with an increased mobilization of immune cells, especially in NK cells and their subpopulations. CONCLUSION: We were able to show, that HIIT enhances the mobilization of NK cells and ILCs to the same extend in AYA cancer patients than in healthy controls. Our pilot study revealed, that exercise is likely to play an important role in the defense against pathogens and neoplastic cells and that AYA cancer patients might benefits from regular exercise programs during anti-cancer treatment. TRIAL REGISTRATION: The study was registered on 13.11.2022, registration number NCT05656651, in the international register of clinical trials https://www. CLINICALTRIALS: gov/ .