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Multiple elevations of cytosolic-free Ca2+ in human neutrophils: initiation by adherence receptors of the integrin family

Theler, J. M.
Wright, S. D.
Published in The Journal of Cell Biology. 1991, vol. 112, no. 6, p. 1249-1257
Abstract Multiple spontaneous transient elevations of cytosolic-free calcium ([Ca2+]i) are observed in single human neutrophils during adherence. The interrelation between adherence and spontaneous [Ca2+]i transients was analyzed by simultaneous monitoring of [Ca2+]i and cell morphology. Fluorescent images of fura 2-loaded neutrophils attached to albumin-coated glass were recorded with a high sensitivity CCD camera while [Ca2+]i was assessed with a dual excitation microfluorimetry. The majority of the initially round cells studied showed changes in shape which started either before or at the same time as the onset of the [Ca2+]i transients. These data suggested that a rise in [Ca2+]i is not a prerequisite for shape change. This conclusion was confirmed by observation of movement and spreading in cells whose [Ca2+]i transients were abolished by chelation of extracellular Ca2+. Instead, our data suggest that spreading or adhesion itself initiates the [Ca2+]i activity. In keeping with this hypothesis, cytochalasin B, which prevents both cell movement and adhesion, completely inhibited generation of [Ca2+]i transients. To determine if the movement alone or adhesion alone is responsible for [Ca2+]i activity, we treated cells with antibodies against the beta chain (CD18, beta 2) or the alpha subunit (CD11b, alpha m) of the dominant leukocyte integrin (CR3). Antibody-treated cells showed normal extension of pseudopods but impaired ability to adhere. Inhibition of adhesion in this way inhibited [Ca2+]i activity. Taken together these results suggest that following sequence of events after contact of neutrophils with surfaces: (a) cell movement and shape change lead to enhanced contact of integrins with the surface; and (b) integrins-mediated adhesion generates multiple [Ca2+]i transients. The [Ca2+]i transients may then control exocytic events associated with movement and may provide a link between adherence and activation or priming of neutrophils to other stimuli.
Keywords Antibodies, Monoclonal/diagnostic useCalcium/ bloodCell Adhesion/drug effectsCell Membrane/physiologyCytochalasin B/pharmacologyCytosol/metabolismEgtazic Acid/pharmacologyFura-2HumansIntegrins/drug effects/ physiologyKineticsMicroscopy, FluorescenceNeutrophils/cytology/drug effects/ physiologySoftware
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Other version: http://jcb.rupress.org/content/112/6/1249.full.pdf
PMID: 1900302
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