Circulating monocytes are not the source of elevations in plasma IL-6 and TNF-alpha levels after prolonged running

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.