Long-distance running modulates the expression of leucocyte and endothelial adhesion molecules.

There still exist many unanswered questions whether physical exercise is beneficial or harmful to the immune system. The 'open-window' post-exercise hypothesis states that athletes are more susceptible to infections after exercise, but there is a need for further elucidation. The aim of the present study was to investigate the effect of long-distance running on leucocyte expression of selected adhesion molecules as well as the plasma levels of soluble leucocyte- and endothelium-derived adhesion molecules. Twenty-seven men participating in Oslo marathon together with 16 entrants (eight men and eight women) in the Oslo half-marathon were recruited to this study. Venous blood was collected before and immediately after the races for analysing the leucocyte expression of CD62L, CD11b and CD14 with the help of flow cytometry, and plasma concentrations of soluble (s) sE-selectin, sL-selectin, sP-selectin, sVCAM-1, sICAM-1 and sCD14 were assessed by means of enzyme-linked immunosorbent assays. A significant increase of leucocyte CD11b expression was observed following both races, compared to the pre-race situation. Monocyte CD14 expression increased only after the marathon race. After both races, CD62L expression was significantly lowered on all leucocyte subsets, whereas the plasma levels of sE-selectin, sP-selectin, sL-selectin, sVCAM-1, sICAM-1 and sCD14 were all increased. Altogether, these changes negatively influence the ability of leucocytes to adhere to and actively transmigrate the endothelium to reach the tissues. Our study thus supports the 'open-window' hypothesis, indicating a reduced capacity to combat infectious agents during the immediate post-exercise period.