SPLENECTOMY IMPAIRS LYMPHOCYTOSIS DURING MAXIMAL EXERCISE

To evaluate the role of the spleen for the exercise-induced lymphocyto sis, six splenectomized subjects and six matched control subjects cycl ed for 12 min at two submaximal work rates corresponding to 50 and 75% of their maximal work capacity, followed by a supramaximal intensity maintained until exhaustion (16 +/- 1 min; mean +/- SE). Venous blood samples were taken before, during, and 2 h after the maximal load. In both groups, the concentration of lymphocytes became elevated during e xercise, but the increase from the level at rest was impaired in the s plenectomized subjects compared with that of the controls (118 +/- 34 vs. 238 +/- 38%; P < 0.05). This was reflected in several lymphocyte s ubsets: cluster designation (CD) 3(+) cells (pan T lymphocytes), 69 +/ - 19 vs. 204 +/- 37%; CD8(+) cells (T lymphocyte subset), 164 +/- 41 v s. 467 +/- 68%; CD16(+) cells [natural killer (NK) cells], 291 +/- 88 vs. 870 +/- 177%; CD56(+) cells (NK cells), 301 +/- 108 vs. 753 +/- 18 7%. Also, the specific NK cell lysis of target cells (NK cell activity ) during exercise was lower for the splenectomized subjects (30 +/- 7% ) than that of the control subjects (52 +/- 10%), but evaluation of ly tic units indicates that this was due to a reduced number of NK cells in the assay rather than insufficient cell lysis. Plasma catecholamine s reached the same level in the splenectomized subjects and control su bjects, which was taken to reflect that the activity of the sympatheti c nervous system was similar in the two groups of subjects. Thus the m ajor finding of this study is that the spleen is important for lymphoc ytosis during exercise, accounting for two-thirds of the increase in T lymphocytes and NK cells.