MODERATE EXERCISE LEADS TO DOWN-REGULATION OF B1 AND B2 INTEGRINS ON MONOCYTES AND LYMPHOCYTES 548

Intravascular adhesion of leukocytes plays a role in the pathogenesis of chronic vascular disease. Since leukocytes adhesion is mediated by integrins we tested the hypothesis that surface expression of the integrin adhesive receptors LFA-1 (cd11a/cd18), MAC-1 (cd11b/cd18), gp150/95 (cd11c/cd18) and VLA-4 (cd29/cd49) is decreased by moderate exercise. Surface expression of integrins was measured by FACS analysis in 19 healthy subjects (16 males, 3 females, 36.6±8.7 yrs, 177.1±7.5 cm, 70.3±8.1 kg) before and after a submaximal 3 h run using monoclonal antibodies against cd11a, cd11b, cd11c, cd18, cd29 and cd49. In addition, we compared resting integrin expression in this group to an age-matched group of sedentary subjects. White blood cell count increased from 5300/μl to 9740/μl during exercise(p<0.001). Expression of cd11a (94±24 vs. 78±14) and cd18(128±31 vs 102±21) on lymphocytes and of cd11a (104±25 vs 85±16), cd11c (497±171 vs. 408±126), cd29 (109±16 vs. 89±16) and cd49 (69±8 vs. 54±11) on monocytes was decreased after exercise (p<0.05). In contrast, integrin expression on granulocytes was not altered. Comparison of exercising and sedentary subjects showed a significantly decreased expression of integrins in exercising subjects. Our results demonstrate that moderate exercise leads to a down-regulation of integrin receptors on monocytes and lymphocytes. This down-regulation of adhesion molecules may result in decreased adhesion and infiltration of leukocytes into the vessel wall. This phenomenon may play a role in the beneficial effect of moderate exercise in prevention of chronic vascular disease.