Recruitment and Recirculation of Leukocytes after an Ultramarathon Run: Preferential Homing of Cells Expressing High Levels of the Adhesion Molecule LFA-1

Abstract

The α_Lβ₂ (CD11a/CD18) integrin LFA-1 (lymphocyte function-associated antigen-1) mainly contributes to the firm arrest of leucocytes on the endothelium. Its cell surface density is thought to be important for the exercise-induced homing of leucocytes. 9 athletes (7 males, 2 females, age 36-68 years, body mass 64±10 kg, height: 175±10 cm) absolved a competitive 100 km run in 8:07 hours (range: 7:29-9:50 hours). Immunophenotyping of circulating leucocytes and data aquisition by three colour flow cytometry before and up to 3 hours after the race showed that post exercise lymphocyte subpopulations with a higher expression of CD11a like CD3⁺CD8⁺CD45RO⁺ T-cells, natural killer cells (CD3^-CD16/CD56⁺) and cytotoxic, not MHC-restricted T-cells (CD3⁺CD16/CD56⁺) decreased significantly more than CD45RO⁺ and CD45RO^- helper-T-cells (CD3⁺CD4⁺), CD3⁺CD8⁺CD45RO^- T-cells and B-cells (CD19⁺), which have lower levels for CD11a. Cell concentrations of regular monocytes (Fcγ receptor 3 negative, LFA-1 low positive) increased, whereas mature monocytes (Fcγ receptor 3 low or high positive respectively, LFA-1 high positive) decreased. In conclusion the surface density of the adhesion molecule LFA-1 on leucocytes is likely to contribute significantly to the extent of leucocyte's homing after long endurance exercise.

Key words

Exercise - ultramarathon - homing - adhesion - lymphocytes - monocytes - CD16 - CD11a