Circulating leucocyte and lymphocyte subpopulations before and after intensive endurance exercise to exhaustion

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Abstract
Summary Seventeen healthy cyclists [age 20.8 (SD 4.8) years; body mass 68.3 (SD 7.7) kg; body fat, 11.4 (SD 2.6) %; height, 179.1 (SD 5.9) cm;\(\dot VO_{2max} \) 60.9 (SD 7.4) ml · kg−1 · min−1] conducted intensive endurance exercise to exhaustion (stress test, ST) on a cycle ergometer at 110% of their individual anaerobic threshold [Than,individua; exercise intensity, 3.97 (SD 0.6) W · kg−1 ; duration, 23.9 (SD 8.3) min; maximal lactate concentration, 7.39 (SD 2.59) mmol · 1−1]. The distribution of leucocyte subpopulations was measured flow cytometrically: before, immediately after (0), 5 (+5), 30 (+30) and 60 (+60) min after ST. The lymphocytes (0 min) and granulocytes (+60 min) were mainly responsible for the increase of leucocytes. Lymphocytes were significantly lower at +30 and + 60 min than before. CD3−CD16/CD56+ (+480%) and CD8+-lymphocytes (+211%) increased at 0 min more than the other lymphocyte subpopulations (CD3+-cells, +100%; CD4+ cells, +56%; CD19+-cells, +64%). CD3−CD16/CD56+-and CD8+-cells also were mainly responsible for the decreased values of lymphocytes at +30 min and +60 min compared to before. At 0 min naive CD8+ cells (CD45RA+, CD45RO−) increased more than memory CD8+-cells (CD45RA−, CD45RO+). Changes of naive and memory CD4+-cells did not differ. All lymphocyte subpopulations, in particular CD8+- and CD3−CD16/CD56+-cells, decreased rapidly between 0 min and 5 min. We conclude that an intensive endurance exercise to exhaustion causes a mobilisation of lymphocytes, especially of natural killer cells (CD3−CD16/CD56+) and naive, unprimed CD8+ cells (CD45RA+, CD45RO−) which may be transported to injured muscles. The decreased cell numbers of the latter subpopulations are possibly one reason for the susceptibility to infections during the first hours after exercise. Furthermore, an exact definition of the intensity of exercise and times of taking blood is essential for comparing results describing cell parameters during or after exercise.