Calcium signaling capacity of the CD11b/CD18 integrin on human neutrophils.
The CD11b/CD18 integrin is a major cell adhesion molecule of myelomonocytic cells. Exposure of human neutrophils in suspension to CD11b or CD18 monoclonal antibodies (mAbs)2 does not affect the resting level of cytosolic free Ca2+ in these cells; however, a subsequent cross-linking of either of these antibodies triggers a prompt and significant cytosolic-free Ca2+ transient lasting about 10 min. The rise in cytosolic-free Ca2+ (from 130 +/- 2 to 414 +/- 12 nM or 111 +/- 12 to 331 +/- 22 nM caused by cross-linking of CD11b or CD18 subunits, respectively) is due to both mobilization of Ca2+ from intracellular stores and influx of Ca2+ across the plasma membrane. Cross-linking of the common leukocyte antigen (CD45) did not alter the basal level of cytosolic free Ca2+. In accordance with other adherence-induced phenomena and with CD11/CD18-mediated phagocytosis, these Ca2+ signals were only modestly affected by pertussis toxin. Thus, the present data clearly indicate that the CD11b/CD18 integrin on human neutrophils is capable of inducing a prompt cytosolic-free Ca2+ signal. These findings directly support the recent suggestion that the CD11b/CD18 integrin is responsible for the "spontaneous oscillations" of cytosolic-free Ca2+ observed in adherent neutrophils and, at least partially, also explain how integrin-mediated adherence can modify the functional responsiveness of neutrophils to a subsequent agonist stimulation.
Department of Cell Biology, University of Linköping, Sweden.
J
J
Ng-Sikorski
R
R
Andersson
M
M
Patarroyo
T
T
Andersson
D015703:Antigens, CD / Q000378:metabolism*; D018845:CD11 Antigens; D018821:CD18 Antigens; D002118:Calcium / Q000378:metabolism*; D002448:Cell Adhesion; D003432:Cross-Linking Reagents; D003600:Cytosol / Q000378:metabolism; D006801:Humans; D009504:Neutrophils / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D037342:Pertussis Toxin; D015398:Signal Transduction / Q000187:drug effects; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D015703:Antigens, CD; D018845:CD11 Antigens; D018821:CD18 Antigens; D003432:Cross-Linking Reagents; D010566:Virulence Factors, Bordetella; D037342:Pertussis Toxin; D002118:Calcium