K. Furusawa et al., SHORT-TERM ATTENUATION OF NATURAL-KILLER-CELL CYTOTOXIC ACTIVITY IN WHEELCHAIR MARATHONERS WITH PARAPLEGIA, Archives of physical medicine and rehabilitation, 79(9), 1998, pp. 1116-1121
Objective: To investigate homeostasis of the immune system in athletes
with spinal cord injuries during and after racing a wheelchair marath
on. Design: The study examined changes in the number and function of n
atural killer (NK) cells in nine male wheelchair marathon athletes (sp
inal cord injuries between T5 and T12) who completed the 15th Oita Int
ernational Wheelchair Marathon Race. Blood samples were obtained the d
ay before, immediately after, and 1 day after the race. Blood samples
were also obtained from seven age-matched control subjects with spinal
cord injuries but who did not exercise regularly. Results: The number
of peripheral leukocytes increased (p < .01) immediately after the ra
ce. In contrast, the number of peripheral NK cells and NK cell cytotox
ic activity significantly decreased from 310 +/- 130/mu L to 133 +/- 6
1/mu L and from 42.6% +/- 3.0% to 38.2% +/- 3.2%, respectively (mean /- SD), immediately after the race. Plasma cortisol levels were increa
sed after the race. However, all parameters returned to control levels
within 24 hours. Measurements in control subjects did not change thro
ughout the experiment. Conclusion: These findings suggest that racing
a marathon suppressed peripheral NK cell number as well as NK cell cyt
otoxic activity in wheelchair athletes and that this was probably medi
ated by increased postrace cortisol levels. Wheel chair marathon athle
tes are advised to take extra precaution to avoid infection within 24
hours after racing because of the transient suppression of NK cell cyt
otoxic activity during this period. (C) 1998 by the American Congress
of Rehabilitation Medicine and the American Academy of Physical Medici
ne and Rehabilitation.