Lymphocyte dynamics during acute exercise in type one diabetes

Type 1 diabetes (T1D) is a T cell mediated autoimmune disease that targets and destroys insulin-secreting pancreatic beta cells. Exercise induced lymphocytosis facilitates immune surveillance and regulation. This study aimed to explore whether exercise could modulate the T1D autoimmune process through regulation of lymphocyte mobilisation and trafficking. N=12 T1D (mean age 33.2yrs, predicted VO2 max 32.2 mL/(kg·min), BMI 25.3Kg/m2) and N=12 control (mean age 29.4yrs, predicted VO2 max 38.5mL(kg.min), BMI 23.7Kg/m2) male participants completed 30-minutes cycling at both 40% (moderate) and 80% predicted VO2 max (vigorous) on separate days and in a fasting state. Peripheral blood was collected at baseline, immediately post-exercise, and 1 hour post-exercise. Intensity dependent lymphocytosis was observed in both groups; specifically, CD8+ effector memory CD45RA+ (EMRA) T cells and CD56dimCD16bright NK cells. However, the percentage increase of these subsets was blunted in T1D following vigorous intensity exercise. The reasons for this may include differences in blood glucose levels, adrenaline responses, and sequestration of these subsets in the pancreas of people with T1D. Lymphocyte trafficking was also regulated by vigorous exercise in T1D. Transmigration of lymphocytes was significantly suppressed during the recovery period together with a reduction in adhesion molecules on T cells following vigorous exercise