Fluid pinocytosis is a recently described cellular event of neutrophils, the major cellular component of acute inflammation, in response to stimulation with chemotactic factors (CF). Pinocytosis occurs simultaneously with other FC-induced neutrophil events relating to the kinetic or locomotory response in contrast to early events, such as the burst of oxidative metabolism and secretory response to CF. It is postulated through our previous work that the CF-induced pinocytosis is related to the cellular events of locomotion and not solely to CF ligand-receptor complex internalization and receptor recycling. This study is to further characterize the process of CF-induced pinocytosis neutrophils; investigate the phenomenon with regard to the events of locomotion and the modulation of membrane receptors for CF; and study the process in developing myeloid cells, myeloid leukemia cells, and neutrophils from clinical states of known neutrophil dysfunction. Fluid pinocytosis will be measured using a fluorescent flow cytometric assay and radiolabeled, fluid phase marker uptake assays. Ultrastructural morphologic and biochemical subcellular fractionation methods will be employed using enzymatic, radioactive, and morphologic markers and pharmacologic inhibitors of pinocytosis to study the subcellular processing and relationship to adsorptive endocytosis of this process. The effects of membrane perturbations in regard to membrane fluidity, as measured by fluorescence polarization, and its relationship to fluid pinocytosis will be studied. Studies with fluorescent probes and pharmacologic agents to examine fluid pinocytosis during neutrophil chemotaxis will be employed to investigate the interrelationship of the two processes. Flow cytometric analysis of pinocytosis in developing myeloid cells and leukemic cell lines induced to differentiate in liquid cell culture will be used to characterize the process in immature myeloid cells. lt is hoped that these studies will characterize and define the biologic significance of stimulated fluid pinocytosis in neutrophils. (MB)
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