Berlin 2005 – scientific programme

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AKB: Biologische Physik

AKB 100: Poster Session I

AKB 100.15: Poster

Saturday, March 5, 2005, 16:45–18:45, Poster TU D

A combined Langevin and adhesive dynamics approach to rolling adhesion of leukocytes — •Christian Korn and Ulrich Schwarz — Max-Planck-Institut für Kolloide und Grenzflächen, 14424 Potsdam

Extravasation of white blood cells (leukocytes) from the blood flow is preceeded by rolling adhesion on the vessel walls, which can be studied under controlled conditions in flow chamber experiments. Due to low Reynolds numbers the hydrodynamics is described by the Stokes equation. For the initial stages of rolling adhesion, elastic effects can be disregarded. Therefore we model the leukocytes as hard spheres in shear flow above a wall. Combing Stokes equation and Brownian motion leads to a Langevin equation which is known as the Stokesian dynamics equation. The presence of the wall leads to mobility functions which dependent on position and thus result in non-trivial noise terms in the Langevin equation. Specific binding through receptors on the cell and ligands on the wall is included in the Langevin equation as spring-like external forces (adhesive dynamics). Within this conceptual framework, we study adhesion to patterned ligands, the effect of loading rate, bond cooperativity and competition between different receptor-ligand systems.