Effect of physical exercise on in vitro production of interleukin 1, interleukin 6, tumour necrosis factor-α, interleukin 2 and interferon-γ

The present study was designed to examine the effect of physical exercise on production of interleukin-1 (IL-1), interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α), interleukin-2 (IL-2) and interferon-γ (IFN-γ). Ten young, healthy volunteers underwent 60-min bicycle exercise at 75% of maximal oxygen uptake (V̇O₂max). Blood samples were collected before and during the last minutes of exercise, as well as 2 h and 24 h later. Blood mononuclear cells (BMNC) were stimulated in vitro with either bacterial lipopolysaccharide or phytohaemagglutinin, and the supernatants were tested for the above-mentioned cytokines using bioassays as well as ELISA techniques. The production of IL-6 increased significantly 2 h after exercise, furthermore the production of IL-1α and IL-1β was enhanced, although only borderline significant. TNF-α, IL-2 and IFN-γ did not fluctuate in relation to exercise. The increased amounts of IL-1 and IL-6 in the supernatants generated from a fixed number of BMNC are most likely explained by the increased percentage and absolute number of blood monocytes 2 h after exercise. IL-2 and IFN-γ are mainly produced by CD4+ and CD16+ cells. During exercise the CD4+ subset decreases, while the CD16+ subset increases. The finding of unchanged production of IL-2 and IFN-γ was therefore expected.