title: Reduction in resting plasma granulysin as a marker of increased training load.
abstract: Granulysin is a cytolytic granule protein released by natural killer cells and activated cytotoxic T lymphocytes. The influence of exercise training on circulating granulysin concentration is unknown, as is the relationship between granulysin concentration, natural killer cell number and natural killer cell cytotoxicity. We examined changes in plasma granulysin concentration, natural killer cell number and cytotoxicity following acute exercise and different training loads. Fifteen highly trained male cyclists completed a baseline 40-km cycle time trial (TT401) followed by five weeks of normal training and a repeat time trial (TT402). The cyclists then completed four days of high intensity training followed by another time trial (TT403) on day five. Following one final week of normal training cyclists completed another time trial (TT404). Fasting venous blood was collected before and after each time trial to determine granulysin concentration, natural killer cell number and natural killer cell cytotoxicity. Granulysin concentration increased significantly after each time trial (P<0.001). Pre-exercise granulysin concentration for TT403 was significantly lower than pre-exercise concentration for TT401 (-20.3 +/- 7.5%, P<0.026), TT402 (-16.7 +/- 4.3%, P<0.003) and 7T404 (-21 +/- 4.2%, P<0.001). Circulating natural killer cell numbers also increased significantly post-exercise for each time trial (P<0.001), however there was no significant difference across TT40 (P>0.05). Exercise did not significantly alter natural killer cell cytotoxicity on a per cell basis, and there were no significant differences between the four time trials. In conclusion, plasma granulysin concentration increases following moderate duration, strenuous exercise and is decreased in response to a short-term period of intensified training.
authors.affiliation: School of Human Life Sciences, University of Tasmania, Newnham, Launceston, Tasmania, 7250, Australia. Cecilia.Shing@utas.edu.au
authors.forename: Cecilia M
authors.initials: CM
authors.lastname: Shing
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Ogawa
authors.forename: Xiumin
authors.initials: X
authors.lastname: Zhang
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Nagatomi
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Peake
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Suzuki
authors.forename: David G
authors.initials: DG
authors.lastname: Jenkins
authors.forename: Jeff S
authors.initials: JS
authors.lastname: Coombes
mesh_terms: D000328:Adult; D000945:Antigens, Differentiation, T-Lymphocyte / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D005080:Exercise Test; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology; D007958:Leukocyte Count; D008297:Male; D012016:Reference Values; D013997:Time Factors
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D015415:Biomarkers; C075005:GNLY protein, human