CHARACTERIZATION OF MORPHOLOGICAL CHANGES IN ACTIVATED NEUTROPHILS

Abstract

Neutrophils leave the vasculature and migrate along a chemotactic gradient to an infectious focus where they ingest invading microorganisms. To accomplish this myriad of functions, neutrophils undergo considerable morphological changes. Treatment of neutrophils with the chemotactic peptide, formyl-methionyl-leucyl-phenylalanine (fMLF), 5 x 10(-9) M, results in a change in cellular morphology that includes formation of agranular projections and polarization of the cell. As determined by flow cytometric analysis these morphological change occurs within 5 min, peaks by 30 min, and are accompanied by a change in forward and right angle light scatter. Fibrinogen prolongs the fMLF-induced response through 4 h. Changes in right angle light scatter parallel morphological change observed by light microscopy, indicating that flow cytometry can also be used to evaluate changes in cell morphology. Other chemoattractants were less effective at inducing a change in morphology — fMLF >> LTB4 = C5a > 1L-8 > PAF = LPS. Disruption of microtubules with colchicine altered forward light scatter and cell polarization while the disruption of microfilaments with cyto B abrogates all morphological alterations, demonstrating the involvement of the cytoskeleton in the chemotactic process of neutrophils.