H-13N Free Communication/Poster Immunology
Alteration in lymphocyte trafficking and distribution affects immune response. Circulating number of NK cells decreases after high intensity exercise. CXCR4 is a chemokine receptor supposedly important for tissue distribution of lymphocyte.
We asked whether exercise-induced NK cell trafficking is mediated by CXCR4 on NK cells.
Seven young healthy men (age:23.7 +/- 0.8 yrs) volunteered for this study. Subjects performed cycling exercise for 90 min at exercise intensity of 70% peak oxygen uptake. Heparinized blood samples were obtained before and immediately after exercise. Plasma was kept frozen below −80° until use. 1) PBMC obtained 5 days after exercise when acute effect of exercise became negligible were co-cultured with stored plasma obtained before and immediately after exercise with or without glucocorticoid receptor antagonist RU486, and analyzed for CXCR4 expression. 2) PBMC obtained before and immediately after exercise were cultured in culture medium alone and analyzed for CXCR4 expression after incubation to examine whether NK cells were primed in vivo for CXCR4 expression. 3) Post-exercise plasma treated PBMC were analyzed for their ability to migrate through membrane filters in response to CXCL12.
1) Post-exercise plasma augmented CXCR4 expression, however, glucocorticoid receptor antagonist RU486 could not reverse CXCR4 augmentation on NK cells, and the level of CXCR4 expression even after augmentation remained low. 2) No augmentation of CXCR4 was observed on NK cells obtained immediately after exercise even after 72 hr of culture in fresh medium. 3) Cortisol and post-exercise plasma treatment did not enhance migration of NK cells towards CXCL12.
Unlike T cells, CXCR4 on NK cells may not be involved in altered leukocytes trafficking during and after exercise.