A possible role for the Pi-linked CD14 molecule in human monocyte and granulocyte signal mediation was investigated. Using flow cytometry and the fluorescent indicators Fluo-3 and dihydrorhodamine-123 it was shown that crosslinking of the CD14 molecule induces an increase in monocyte and granulocyte cytoplasmic calcium concentration and monocyte H2O2 production. These responses were found to be independent of IgG Fc receptors and suggest an intrinsic signal mediating capacity of the CD 14 molecule.
