LAUSR

Acute exercise evokes an almost instantaneous lymphocytosis, which is followed by sustained lymphopenia within just 30–60 min of exercise cessation. The aim of this study was to characterize for the first time the immediate (order of minutes) post-exercise kinetics of lymphocyte egress, and to determine if lymphocyte egress is associated with heart rate recovery following exercise. 11 healthy subjects exercised for 30-min at 80 percent peak cycling power. Blood samples were collected from an intravenous catheter before exercise, during (+15 and + 30 min) exercise, and at exactly +1, +2, +3, +4, +5 and +10 min after exercise cessation. Complete blood counts and flow cytometry was used to enumerate total lymphocytes, CD3 + T-cells, CD4 + T-cells, CD8 + T-cells, NK-cells and gamma-delta T- cells in whole blood. Compared to the peak lymphocyte count during exercise, the lymphocyte count had fallen significantly (−14 percent) after just 2 min of exercise recovery. After 5 and 10 min of exercise recovery, the lymphocyte count was −23 percent and −28 percent of peak values, respectively. NK cells were fastest to egress peripheral blood, followed by CD8 + T-cells. Further, the egress of both NK-cells and CD8 + T-cells was strongly correlated with recovery heart rate upon exercise cessation. In conclusion, lymphocyte egress occurs within the first few minutes of exercise recovery and may be dependent on how quickly hemodynamic equilibrium is restored.