Effect of prolonged exercise and carbohydrate ingestion on type 1 and type 2 T lymphocyte dustribution and intracellular cytokine production in humans

The present study was undertaken to examine the role of the exercise-induced stress hormone response on the regulation of type 1 and type 2 T lymphocyte intracellular cytokine production. Subjects performed 2.5 h of cycling exercise at 65% maximal O-2 uptake while ingesting a 6.4% carbohydrate (CHO) solution, 12.8% CHO solution, or a placebo. Peripheral whole blood samples were stimulated and stained for T lymphocyte surface antigens (CD4 and CD8). Cells were then permeabilized, stained for intracellular cytokines, and analyzed using flow cytometry. Exercise resulted in a decrease (P <0.05) in the number and percentage of IFN-γ positive CD4(+) and CD8(+) T lymphocytes. These stimulated cells produced less IFN-γ immediately postexercise (P <0.05) and 2-h postexercise (P <0.05) compared with preexercise. However, CHO ingestion, which attenuated the exercise-induced stress hormone response compared with placebo (P <0.05), prevented both the decrease in the number and percentage of IFN-gamma-positive CD4(+) and CD8(+) T lymphocytes and the suppression of IFN-gamma production from stimulated CD4(+) and CD8(+) T lymphocytes. There was no effect of exercise on the number of, or cytokine production from, IL-4-positive CD4(+) or CD8(+) T lymphocytes. These data provide support for the role of exercise-induced elevations in stress hormones in the regulation of type 1 T lymphocyte cytokine production and distribution.