SPATIAL AND TEMPORAL SEPARATION OF CALCIUM SIGNALS IN MYELOID CELLS STIMULATED BY IMMUNE-COMPLEXES

Stimulation of large (100 mu m) human myeloid cells with immune comple xes resulted in Ca2+ spiking. Bath global and regional changes in the, intracellular cytosolic free Ca2+ concentration were detected in resp onse to immune complex stimulation. The regional changes were mediated by release of Ca2+ from stores, whereas global changes were mediated by Ca2+ influx. They occurred independently of each other, with releas e of Ca2+ from intracellular Ca2+ stores being separated from transmem brane influx of Ca2+. Bromophenacyl bromide, an I-plastin binding agen t, inhibited store release without preventing transmembrane influx of Ca2+. The large size of the myeloid cells used here allowed the visual isation of the spatial and temporal separation of store release from t ransmembrane influx of Ca2+, providing further evidence for the existe nce of independent Ca2+ store release and Ca2+ influx mechanisms in th ese cells. (C) 1997 Elsevier Science Inc.