CD11B CD18 EXPRESSION, ADHERENCE, AND CHEMOTAXIS OF GRANULOCYTES IN ADULT-RESPIRATORY-DISTRESS-SYNDROME/

The accumulation of granulocytes in the pulmonary microvasculature is generally thought a cardinal event in the pathology of adult respirato ry distress syndrome (ARDS). However, the mechanism by which granulocy tes are sequestered in the pulmonary vascular bed remains largely unkn own. Because the CD11b/ CD18 membrane receptors mediate various adhesi on-dependent functions, their expression was investigated in granulocy tes from patients during the course of ARDS development in relation to adherence and chemotaxis. CD11b expression of ARDS resting granulocyt es was increased within 24 h of ARDS onset by a factor of two in compa rison with control patients (p < 0.05) and remained significantly incr eased 72 to 120 h later. In contrast, the stimulated expression was si gnificantly decreased only within 24 h of ARDS onset. Adherence was no t modified within 8 h of the onset of ARDS, but was increased at Days 1, 3, and 5. The time course of granulocyte chemotaxis shows a decreas ed chemotaxis capacity during the first 3 d of ARDS, followed by norma lization at Day 5. The dynamic changes observed in the various functio ns studied indicate a possible relationship between the modulation of the CD11b expression and a hyperadhesive state of granulocytes in ARDS . These sticky granulocytes may potentially contribute to the microvas cular injury.