The present study investigated the effect of concentric exercise on cytokine plasma levels and cytokine pre-mRNA in blood mononuclear cells (BMNCs). Healthy young moderately trained men performed ergometer bicycle exercise for 1 h at 75% of maximal oxygen uptake. The levels of plasma interleukin (IL)-6 increased significantly during exercise, but plasma levels of IL-1 alpha, IL-1 beta, and tumor necrosis factor-alpha (TNF-alpha) were below the detection limit in most subjects. Pre-mRNA for IL-1 alpha, IL-1 beta, IL-6, and TNF-alpha could be detected in BMNCs, but the amounts did not change in relation to exercise. These results indicate that, although the absolute number of monocytes increases during exercise and the percentage of CD14+/HLA-DR+ and CD14+/HLA-DR- monocytes increases after exercise, the increased plasma levels of IL-6 during exercise is not likely to be a result of activated monocytes in peripheral blood.

No abstract

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-alpha (TNF-alpha), interleukin-2 (IL-2) and interferon-gamma (IFN-gamma). Ten young, healthy volunteers underwent 60-min bicycle exercise at 75% of maximal oxygen uptake (VO2max). 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-1 alpha and IL-1 beta was enhanced, although only borderline significant. TNF-alpha, IL-2 and IFN-gamma 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-gamma 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-gamma was therefore expected.

No abstract

High-avidity IgG antibodies to the cytokine interleukin-6 (IL-6) were found in sera of apparently healthy adult individuals. These antibodies specifically interfered with an ELISA (enzyme-linked immunosorbent assay) for IL-6 in which specific polyclonal rabbit antibodies to human recombinant IL-6 (rIL-6) were used. Furthermore, using precipitation of 125I-rIL-6 with rabbit antibodies to human immunoglobulins (Ig), the sera of 7 out of 68 Danish blood donors were found to contain specific antibodies in substantial amounts. Judged by ELISA interference, gel filtration of sera incubated with 125I-rIL-6 and second antibody precipitation of 125I-rIL-6, IgG seemed to be the dominant IL-6 binding protein in these normal sera. Using specific antibodies to human Ig light chains, it was found that the anti-IL-6 antibodies were of polyclonal origin. Moreover, there are at least two epitopes on the IL-6 molecule, because more than one IgG bound to some IL-6 molecules at the same time. The anti-IL-6 antibodies did not cross-react with a number of other human recombinant-derived and native cytokines. The antibodies recognized native as well as rIL-6, but preferentially monomeric IL-6.