CIRCULATING LEUKOCYTE SUBPOPULATIONS IN SEDENTARY SUBJECTS FOLLOWING GRADED MAXIMAL EXERCISE WITH HYPOXIA

Ten healthy sedentary subjects [age, 27.5 (SD 3.5) years; height, 180 (SD 5) cm; mass, 69.3 (SD 6.3) kg] performed two periods of maximal in cremental graded cycle ergometer exercise in a supine position. Random ly ordered and using an open spirometric system, one exercise was carr ied out during normoxia [maximal oxygen consumPtiOn (VO2max) = 38.6 (S D 3.5) ml . min-1 . kg-1; maximal blood lactate concentration, 9.86 (S D 1.85) mmol . l-1; test duration, 22.6 (SD 2.7) min], the other durin g hypoxia [VO2max = 33.2 (SD 3.2) ml . min-1 . kg-1; maximal blood lac tate concentration, 10.38 (SD 2.02) mmol . l-1; test duration, 19.7 (S D 2.8) min]. At rest, immediately (0 p) and 60 min (60 p) after exerci se, counts of leucocyte subpopulations (flow cytometry), cortisol and catecholamine concentrations were determined. At 0 p in contrast to no rmoxia, during hypoxia there was no significant increase of granulocyt es. There were no significant differences between normoxia and hypoxia in the increases from rest to 0 p in counts of monocytes, total lymph ocytes and lymphocyte subpopulations [clusters of differentiation (CD) , CD3+, CD4+CD45RO-, CD4+CD45RO+, CD8+CD45RO-, CD8+CD45RO+, CD3+HLADR, CD3-CD16/CD56+, CD3-CD16/CD56+, CD19+] as well as adrenaline, noradr enaline and cortisol concentrations. The counts of CD3-CD16/CD56+- and CD8+CD45RO+-cells increased most. At 60 p, CD3-CD16/CD56+ and CD3+CD1 6/CD56+-cell counts were below pre-exercise levels and under hypoxia s lightly but significantly lower than under normoxia. We concluded that the exercise-induced mobilization and redistribution of most leucocyt e and lymphocyte subpopulations were unimpaired under acute hypoxia at sea level. Reduced increases of granulocyte counts during the study a nd reduced cell numbers of natural killer cells and cytotoxic, not maj or histocompatibility complex-restricted T-cells, only indicated margi nal effects on the immune system.