Leukocyte Deformation and Endothelial Cell Contact Mechanics During IncipientMembrane Peeling and Cell Rolling

摘要

Leukocyte (WBC) adhesion to venular endothelium (EC) is an important step in theimmune response which precedes their emigration through the microvessel wall. To assess the relationship between membrane WBC mechanics and the formation and disruption of WBC-EC bonds, measurements of transients in contact area and WBC shape were made during adhesion in postcapillary venules of the rat mesentery during control conditions (spontaneous adhesion), in response to exposure to the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (FMLP) and following tissue exposure to interleukin-1Beta (IL-1). To assess the roles of WBC deformability, adhesion was also studied during suffusion with colchicine and cytochalasin B (CB). Frame-by-frame analysis of video recordings facilitated measurement of the length of the contact zone between WBC and EC L(sub c) and the acute angle (theta) between the trailing edge of the WBC membrane and EC surface. During the initial adhesion, L(sub c) was found to steadily increase with time as new bonds were formed, and to subsequently decrease with time as the trailing edge of the WBC membrane began to peel away from the EC. The contact angle at the trailing edge of the cell decreased exponentially for control, IL-1, CB, and colchicine.