Does Exercise Alter Intracellular Cytokine Expression Pattersn in PBMCs?

Abstract

0592 Background: Brief bouts of strenuous physical activity induces significant alterations in secretion patterns of inflammatory and growth mediators. These immune/growth mediators are secreted by circulating peripheral blood mononuclear cells and are manifested by elevations in IL-1, IL-6, TNF-a, growth hormone and IGF-1. Yet, no clear pattern of secretion from these cells has been established. PURPOSE: This study was designed to examine exercise-induced changes in intracellular cytokine and growth factor concentrations in peripheral blood mononuclear cells. Methods: Six healthy untrained men (20 y/o ± 4), performed 30 min of a cycling exercise at 70% of VO2 max. Blood samples were drawn at pre-exercise, peak-exercise and 1 hour post-exercise. 100 ìl of blood from each sample was mixed well and incubated with a surface Abs in the dark at RT for 30 minutes. RBC were lysed, cell suspensions were centrifuged, and supernatants removed without disturbing the cell pellet. 500 ìl FACS Permeablizing Solution were added to each tube and fluorescent-conjugated intracellular mAbs added and incubated in dark for 30 min. 10,000 cells were acquired by flow cytometer. Results: Circulating leukocyte subset counts were elevated during and 1 h post exercise. Intracellular concentrations for GH, IGF-1, TNF-, IL-6 and IL-1á were elevated in CD4+ T-cells at the 1-hour post exercise. Conclusions: Using flow cytometery, we can now gain insight into how intracellular levels of key mediators change in specific subsets of leukocytes following a brief bouts of exercise. Intracellular GH, IGF-I, and IL-6 were significantly elevated in different PBMC subsets. GH in a known to play a key role in the adaptive responses to exercise, namely by stimulating other growth factors like IGF-I contributing to muscle hypertrophy and angiogenesis. This is the first report that demonstrates an increase in intracellular GH and IGF-1 both in CD4+ T-cell and monocytes. Further studies are needed to elucidate the role these factor in normal growth and development. Supported by NIH grants HD-26939 and GCRC MO1 RR00827Fig: No Caption available.