Rl. Starkie et al., Circulating monocytes are not the source of elevations in plasma IL-6 and TNF-alpha levels after prolonged running, AM J P-CELL, 280(4), 2001, pp. C769-C774
The present study was undertaken to examine the effect of prolonged running
on monocyte intracellular cytokine production and plasma cytokine concentr
ation. Blood samples were collected 1 h before, immediately after, 2 h afte
r, and 24 h after a competitive marathon run. There was no change in the nu
mber of cells spontaneously producing tumor necrosis factor (TNF)-alpha; ho
wever, there was a decrease in the number of cells producing interleukin (I
L)-1 alpha and IL-6 (P < 0.01) postexercise. In contrast, there was an incr
ease in the number of monocytes that responded to lipopolysaccharide stimul
ation by producing IL-1<alpha>, TNF-alpha, and IL-6 (P < 0.01) immediately
and 2 h postexercise; however, these cells contained less cytokine (P < 0.0
5). Plasma IL-6, TNF-alpha, epinephrine, norepinephrine, and cortisol conce
ntrations were markedly increased (P < 0.01) postexercise. These data demon
strate that circulating monocytes are not the source of elevated levels of
plasma IL-6 and TNF-<alpha> after prolonged running. In addition, it is lik
ely that stress hormones result in a decrease in the amount of cytokine pro
duced by LPS-stimulated cells postexercise.