SLOW CALCIUM WAVES IMAGED IN MYELOID CELLS DERIVED FROM NEONATAL CORD-BLOOD

Myeloid cells were derived from neonatal cord blood by culture with gr anulocyte-macrophage colony-stimulating factor for approximately 8 day s. The resultant cell population contained large adherent cells (diame ter greater than or equal to 90 mu m), expressing formylated peptide r eceptors that were functionally coupled to cytosolic free Ca2+ signali ng. Imaging of the cytosolic free Ca2+ changes in these cells revealed initial focal release of Ca2+ from a site from within the cell, with elevated Ca2+ also near the cell edge. Increased cytosolic free Ca2+ m oved as a slow oscillating wave across the cell (velocity 1 mu m/s). A s similar events may occur in mature neutrophils and monocytes but be difficult to resolve because of the small size of these cells, it was concluded that neonatal myeloid cells may provide a useful model syste m for the investigation of Ca2+ signaling in myeloid cells.