A Polymer Mixing Approach to Chemoattractant-Stimulated Neutrophil Adhesion
We have used photometric and aqueous phase polymer affinity techniques to investigate the kinetics and surface thermodynamics of neutrophilic leukocyte responses to the soluble bacterial chemotaxin N-formyl methionyl leucyl phenylalanine (fMLP). Unlike the relatively slow responses of macrophages to particles, neutrophils respond to chemoattractants within seconds and display a complex series of time-dependent changes which in part reflect cellular adaptation to the chemotaxin by surface receptor internalisation [1,2]. The kinetics of these changes can be resolved by photometric methods, but not by the relatively slow techniques of macroscopic polymer phase wetting. We have therefore used the fungal metabolite cytochalasin B to prevent reversal of the rapid neutrophil responses to fMLP. Under these conditions, wetting of the neutrophils by dextran/PEG phases is essentially independent of time, and depends only on the dose of chemoattractant. The dose-response curves for fMLP induced cell aggregation and increased dextran phase affinity are similar, each with an ED50 of 2 x 10−8 M, suggesting that the two processes may have the same basis, for example in specific granule glycoproteins which become expressed on the cell surface during aggregation. By contrast, chemotactic cell surface ruffling (assessed either by digital image analysis of photomicrographs or by perpendicular light scattering from the cell suspensions) and oxygen radical-dependent chemiluminescence have dose-response curves with values of ED50 ten times lower and higher, respectively, than aggregation and phase affinity changes.
KeywordsContact Angle Light Transmission Interfacial Free Energy Surface Thermodynamic Cell BioI
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