E. Fernandezsegura et al., SHAPE, F-ACTIN, AND SURFACE-MORPHOLOGY CHANGES DURING CHEMOTACTIC PEPTIDE-INDUCED POLARITY IN HUMAN NEUTROPHILS, The Anatomical record, 241(4), 1995, pp. 519-528
Background: The exposure of human neutrophils to uniform concentration
s of chemoattractants, such as N-formyl peptides, induces morphologica
l cell polarization. In this study we report the temporal sequence of
changes in cell shape, F-actin, and cell surface morphology during cel
lular polarization induced by N-formylmethionyl-leucyl-phenylalanine (
fMLP) in human neutrophils in suspension. Methods: Neutrophil shape ch
anges induced by 10(-8) M fMLP were observed with DIC microscopy. Size
and cellular granularity were analyzed by flow cytometry measuring th
eir forward and side scattered Light, To visualize F-actin distributio
n, neutrophils were labeled with the fluorescence probe FITC-phalloidi
n, and were examined with fluorescence and confocal laser scanning mic
roscopy, Cell surface morphology was assessed with scanning electron m
icroscopy (SEM). Results: The stimulation of round-smooth neutrophils
with nanomolar concentrations (10(-8) M) of fMLP in suspension induced
a temporal sequence of morphological changes during cell polarization
, characterized by 1) increase in size as determined by forward angle
scattered light, 2) rapid redistribution of F-actin from a diffuse cyt
oplasmic localization to the cell periphery, and 3) rapid reorganizati
on of cell surface morphological features, with accumulation of plasma
membrane in the front of polar cells. Four cell shapes were identifie
d with SEM after stimulation of round-smooth neutrophils: round-ridged
, round-ruffled, nonpolar ruffled, and polar cells. These cell shapes
were correlated with a cortical localization, focal aggregates, and mu
ltipolar distribution of F-actin, In polar neutrophils, F-actin became
concentrated in the front of the cell. Conclusions: These findings sh
ow the relation between reorganization of the microfilamentous cytoske
leton and modifications in cell shape and surface features during cell
polarization induced after fMLP activation in neutrophils. This appro
ach offers a powerful tool for further analysis of receptor distributi
on in polarized, motile neutrophils. (C) 1995 Wiley-Liss, Inc.