Changes in Adhesion Molecule Expression on Natural Killer Cell Subsets during Incremental Exercise

Abstract

Human natural killer (NK) cells can be divided into two subsets, CD3-CD16brightCD56dim (CD56dim) and CD3-CD16dim/-CD56bright (CD56bright) NK cells. Our previous research has shown different patterns of increase in CD56dim and CD56bright NK cells with incremental exercise. PURPOSE: To clarify mechanisms of differential cell mobilization, we investigated changes in the expression levels of adhesion molecules on CD56dim and CD56bright NK cells during incremental exercise. METHODS: Nine adult males performed cycle ergometer exercise for 5 min at 50, 90, 120 and 140% ventilatory threshold (VT)-VO2. Venous blood samples were collected at rest and at the end of each exercise-intensity stage. Circulating NK cells subsets and intensities of expression of CD11a, CD18, CD31, CD44, CD49d and CD62L adhesion molecules were determined by flow cytometry. RESULTS: Counts for both cell subsets increased significantly, but proportions to total lymphocytes increased only for CD56dim NK cells. Intensities of expression of CD11a, CD18, CD31 and CD49d did not change on either NK subset throughout the experiment. CD44 expression on CD56bright NK cells showed a non-significant downward trend with exercise intensity. Changes in CD62L expression differed significantly between the two subsets, changes in the CD62Lnegative cell population reflecting mainly CD56dim mobilization. CONCLUSION: These results suggest that exercise-induced mobilization of NK cells occurred mainly in the CD56dim subset, reflecting mainly changes in the CD62Lnegative cell count. Supported by Meiji Life Insurance Company.