Localized hydrodynamics of clustering leukocytes

The recruitment of leukocytes to the endothelial walls is intensively investigated both experimentally and through three dimensional computer simulations. The shear dependent viscosity has been obtained from measured values in post-capillary venules of Wistar rats' cremaster muscle. Localized velocity fields and shear stresses on the surface of leukocytes and near vessel wall attachment points have been computed and discussed for a cluster of recruited leukocytes under generalized Newtonian blood flow with shear thinning viscosity. We have observed one region of maximum shear stress and two regions of minimum shear stress on the surface of the leukocytes close to the endothelial wall. This suggests that the accumulation of selectins attains a minimum value in two regions, rather than in one region, on the surface of the leukocytes. We have also verified that the collective hemodynamic behavior of the cluster of recruited leukocytes establishes a strong motive for additional leukocyte recruitment. From this study we claim that the influence of the leukocytes rolling on the endothelial wall increases the shear stress on both the leukocyte and the endothelial wall which results in activating more signaling mediators during inflammation.