title: Strenuous exercise decreases the percentage of type 1 T cells in the circulation.
abstract: Prolonged strenuous exercise is followed by a temporary functional immune impairment. Low numbers of CD4+ T helper (Th) and CD8+ T cytotoxic (Tc) cells are found in the circulation. These cells can be divided according to their cytokine profile into type 1 (Th1 and Tc1), which produce interferon-gamma and interleukin (IL)-2, and type 2 (Th2 and Tc2) cells, which produce IL-4. The question addressed in the present study was whether exercise affected the relative balance between the circulating levels of these cytokine-producing T cells. Nine male runners performed treadmill running for 2.5 h at 75% of maximal oxygen consumption. The intracellular expression of cytokines was detected following stimulation with ionomycin and phorbol 12-myristate 13-acetate in blood obtained before, during, and after exercise. The percentage of type 1 T cells in the circulation was suppressed at the end of exercise and 2 h after exercise, whereas no changes were found in the percentage of type 2 T cells. Plasma epinephrine correlated negatively with the percentage of circulating CD8+ T cells producing IL-2, whereas peak IL-6 correlated with the percentage of CD8+ IL-4-producing T cells in the circulation. Peak plasma IL-6 correlated with plasma cortisol postrunning. In conclusion, the postexercise decrease in T lymphocyte number is accompanied by a more pronounced decrease in type 1 T cells, which may be linked to high plasma epinephrine. Furthermore, IL-6 may stimulate type 2 T cells, thereby maintaining a relatively unaltered percentage of these cells in the circulation compared with total circulating lymphocyte number.
authors.affiliation: Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Steensberg
authors.forename: A D
authors.initials: AD
authors.lastname: Toft
authors.forename: H
authors.initials: H
authors.lastname: Bruunsgaard
authors.forename: M
authors.initials: M
authors.lastname: Sandmand
authors.forename: J
authors.initials: J
authors.lastname: Halkjaer-Kristensen
authors.forename: B K
authors.initials: BK
authors.lastname: Pedersen
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D018791:CD4 Lymphocyte Count; D018414:CD8-Positive T-Lymphocytes / Q000502:physiology; D016207:Cytokines / Q000378:metabolism; D004837:Epinephrine / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005434:Flow Cytometry; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D012420:Running / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology*
chemical_list: D016207:Cytokines; D015850:Interleukin-6; D018664:Interleukin-12; D007371:Interferon-gamma; D006854:Hydrocortisone; D004837:Epinephrine