A three-dimensional computational fluid dynamic (CFD) model is presented to simulate transient rolling adhesion and deformation of leukocytes over a P-selectin coated surface in shear flow. The computational model is based on immersed boundary method for cell deformation, and stochastic Monte Carlo simulation for receptor/ligand interaction. The model is shown to predict the characteristic ‘stop-and-go’ motion of rolling leukocytes. The objective here is to understand the coupling between external shear flow, cell deformation, microvilli deformation and various biophysical parameters that govern the formation of selectin bonds. We observe that compliant cells roll more stably with lesser fluctuations. Adhesion is seen to occur via multiple tethers, but often one tether is sufficient to support rolling. The force loading on individual microvillus is not continuous, rather occurs in steps. Further, it is also shown that only the microvilli whose undeformed length is above a certain cut off length, participate in bond formation and the cutoff length reduces with increasing cell rigidity.

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