| High-intensity interval training (HIIT) may disrupt immunity. Regulatory T cells (Tregs) are important in restoring immune homeostasis. This study investigated the impact of acute versus 2-weeks HIIT on T-cells in active males. Six blood samples were collected: pre-exercise/pre-training (n=18), first (HIIT1) and last (HIIT6) sessions -- immediately (P0) and 1-hr (P60) post-exercise; post-training (n=11). Using flow cytometry, expression levels of CD40L, CD122, and IFN-gamma were elevated in stimulated T-cells at HIIT1P0. At HIIT1P60, CD69 activation receptor density was enhanced on stimulated T-cells. Percentage of suppressive receptors GARP was reduced on unstimluated Tregs; density of LAP was enhanced in stimulated Tregs. No difference was observed between HIIT1 and HIIT6. Compared to pre-training, LAP-expressing Tregs and density of CD122-expressing CD8low cytotoxic T-lymphocytes (CTLs) were decreased in post-training. Upon stimulation, fewer CD122-expressing CD8low CTLs was detected. These findings suggest acute HIIT transiently perturbs immune homeostasis, while repeated HIIT persistently alters CTL and Treg functions. |
