Measuring Receptor-Mediated Cell Adhesion Under Flow: Cell-Free Systems

Abstract

Leukocytes must bind to vascular endothelium under conditions of flow to perform their appropriate physiological functions, which require trafficking into and out of the tissue space surrounding blood vessels. Trafficking into tissues is required of neutrophils during the acute inflammatory response, and during trafficking of lymphocytes into lymphoid tissue. Egress from blood lumen to tissue involves a series of adhesion-dependent steps, each of which involve different leukocyte adhesion receptors and counterreceptors on the endothelium. Transient adhesion, or rolling, of leukocytes over endothelial cells is a prerequisite to firm attachment and transendothelial migration (1,2).

Clonal Variants of Plasmodium falciparum Exhibit a Narrow Range of Rolling Velocities to Host Receptor CD36 under Dynamic Flow Conditions

“…These unbound pRBCs complicate cell tracking, because unbound cells are not easily differentiated from bound and rolling pRBCs in individual video images. Other cytoadhesion studies have utilized methods to observe both adhesion and detachment rates of cells on substrates (55)(56)(57).…”

Probing dynamic cell–substrate interactions using photochemically generated surface-immobilized gradients: application to selectin-mediated leukocyte rolling

“…36–41 In vitro leukocyte flow assays, however, typically employ surfaces presenting non-specifically adsorbed proteins, 42,43 which are susceptible to changes over time, 11,44 or utilize confluent endothelial cell monolayers, 45 which express multiple relevant ligands but offer little control over ligand site density.…”

“…Previous studies have shown that selectin-mediated rolling under conditions of physiological shear stress can be studied in an in vitro flow assay format, yielding new insights into the biophysical phenomena underlying the first step of leukocyte recruitment. [35][36][37][38][39][40] In vitro leukocyte flow assays, however, typically employ surfaces presenting non-specifically adsorbed proteins, 41,42 which are susceptible to changes over time, 11,43 or utilize confluent endothelial cell monolayers, 44 which express multiple relevant ligands but offer little control over ligand site density.…”