[Effects of fluid shear stress on neutrophil surface expression of adhesion molecules]

Fluid shear is a physiological and functional environment for circulating neutrophils where various chemoattractants and cytokines have different effects on neutrophils, activating them or evoking inflammation. So far there have been abundant in vitro researches demonstrating that while neutrophils are activated, some adhesion molecules, which are expressed on the surface of neutrophils, are necessary to cell-to-cell adhesion, and the quantity or quality of these molecules will be changed. The above results were all obtained under static fluid which is quite different from physiological condition. Recently, we used Low-Shear 30 to provide steady or sinusoidal-oscillated fluid shear stress on separated neutrophils with or without f-MLP/TNF stimulation. FITC-anti CD18 monoclonal antibody and PE-anti CD62L monoclonal antibody were added to label CD18 and CD62L on neutrophils suface respectively. Flow cytometry was used to quantify surface expression and positive cell percentage of these two adhesion molecules. The results demonstrat that fluid shear stress increases the expression of CD18 significantly and decreases the CD62L positive cell percentage, but it does not influence the CD62L expression on the CD62L positive cells. The effects of the different patterns of fluid shear stress are not much different, f-MLP or TNF can slightly decrease the expression of CD18 and make CD62L shedding respectively. When one of the two activators and the fluid shear stress act together, the expression of the two adherent molecules can be added. This indicates that the mechanical and biochemical stiumlative action can produce different effects through different receptors and different signal transduction pathways. So the mechanical environment should be considered in the research of activation and adhesion of neutrophils.