title: Mechanisms of B-lymphocyte suppression induced by acute physical exercise.
abstract: Blood mononuclear cells from 20 healthy untrained volunteers were isolated before, during, 2 hr and 24 hr after bicycle exercise at 80% of VO2 max for 1 hr. A reverse plaque forming cell assay was used to investigate B-lymphocyte function. Stimulation with pokeweed mitogen, recombinant interleukin 2 and Epstein-Barr virus resulted in significant decreases in numbers of IgG-, IgM- and IgA-secreting blood cells during as well as 2 hr after exercise, with reversal to pre-exercise values 24 hr later. During and after physical activity we found an unchanged concentration of CD20-positive B lymphocytes suggesting that the suppression of immunoglobulin secreting cells was not due to changes in numbers of B lymphocytes. A decline in CD4/CD8 ratio was measured only during exercise with normalization after exercise. Therefore the B-lymphocyte suppression, most pronounced 2 hr after exercise, was presumably not due to changes in T lymphocytes also indicated in the experiments using EBV-stimulated cultures since EBV acts directly on B lymphocytes. 2 hr after physical activity an increased level of CD14-positive monocytes were observed and the monocytes expressed higher levels of surface HLA-DR during as well as 2 hr after exercise. Addition of indomethacin caused an increased response only in the IL-2 stimulated cultures, suggesting that IL-2-sensitive activated B lymphocytes are downregulated by prostaglandins. Purified B lymphocytes produced plaques only after EBV-stimulation, and in these cultures no exercise-induced suppression was found, likewise suggesting an inhibitory effect of the activated monocytes.
authors.affiliation: Laboratory of Medical Immunology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: N
authors.initials: N
authors.lastname: Tvede
authors.forename: C
authors.initials: C
authors.lastname: Heilmann
authors.forename: J
authors.initials: J
authors.lastname: Halkjaer-Kristensen
authors.forename: B K
authors.initials: BK
authors.lastname: Pedersen
mesh_terms: D000328:Adult; D000921:Antibody-Producing Cells / Q000276:immunology; D001402:B-Lymphocytes / Q000276:immunology*; D015444:Exercise / Q000502:physiology*; D004854:Herpesvirus 4, Human / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation; D008297:Male; D009000:Monocytes / Q000276:immunology; D011043:Pokeweed Mitogens / Q000494:pharmacology; D013997:Time Factors
chemical_list: D007376:Interleukin-2; D011043:Pokeweed Mitogens