Spreading of human neutrophils is immediately preceded by a large increase in cytoplasmic free calcium.

Abstract

When human polymorphonuclear leukocytes (PMN) are placed on various surfaces, they attach and spread rapidly, increasing their diameter severalfold. The spreading is associated with extensive changes in the cytoskeleton. Since many cytoskeletal events are regulated by Ca2 , we measured the cytosolic free calcium concentration ([Ca2+] Polymorphonuclear leukocytes (PMN) and macrophages placed on a variety of surfaces rapidly adhere and spread themselves out thinly on the surface (1, 2). This is thought to represent a frustrated attempt to phagocytose the surface (3). This process is apparently distinct from adherence to endothelium, as PMN do not spread on an endothelial cell monolayer (4). During spreading, major changes in the organization of the actin-based cytoskeleton have been observed at the light-microscopic level (5, 6) and the ultrastructural level (1, 7). Boyles and Bainton (1) have observed the rapid formation of a network of thin filaments interconnected by globular centers only on the adherent surface of spreading PMN. In spreading macrophages, similar changes are seen (5, 7).Several major cytoskeletal proteins in PMN are regulated by calcium. Gelsolin, when activated by calcium concentrations greater than 100 nM, nucleates actin-filament growth, caps the fast-growing end of filaments, and splits preformed filaments (8). PMN also contain myosin, which, in muscle, is controlled by calcium in a well-characterized fashion (9).In order to measure cytosolic free calcium concentration ([Ca2+]j) in single cells, we developed a method using the calcium-sensitive fluorescent dye quin-2 and quantitative fluorescence microscopy (10). We have adapted that method to fura-2, a successor to quin-2 with improved fluorescence properties, such as an increased quantum yield and lower susceptibility to photobleaching (11

Interferon-γ Corrects the Respiratory Burst Defect In Vitro in Monocyte-Derived Macrophages from Glycogen Storage Disease Type 1b Patients

“…GSD I b MDM did not show cytoplasmic spreading or morphologic alterations concomitant with monocyte differentiation unless cultured in the presence of IFN-y, which then resulted in morphologic changes similar to control cells. After adherence, a rise in intracellular Ca2+, similar to that in respiratory burst activity, is a necessary precedent to spreading in neutrophils (45). We have previously demonstrated depressed Ca2+ mobilization in GSD Ib monocytes that is associated with decreased intracellular Ca2+ stores.…”

Acute-Phase Protein α1-Antitrypsin Inhibits Neutrophil Calpain I and Induces Random Migration

“…Existing data provide clear evidence that neutrophil polarization is linked to intracellular Ca 2+ mobilization (31)(32)(33).…”

Ca2+ and calpain control membrane expansion during rapid cell spreading of neutrophils

“…Pioneering work by Maxfield showed that the spreading of neutrophils and macrophages onto surfaces is preceded by large global cytosolic free Ca 2+ signals (Kruskal et al, 1986: Kruskal andMaxfield, 1987). These cytosolic free Ca 2+ signals were caused by adhesive signals to the cell from the substrata, and it has subsequently been shown that immobilisation of b2 integrin by surfaces (Jaconi et al, 1991;Pettit and Hallett, 1996) or cross-linking by anti-integrin antibodies (Ng-Sikorski et al, 1991: Petersen et al, 1993 triggers similar Ca 2+ signals.…”