Fc Receptorsfor lgG on HumanNeutrophils: Analysisof Structureand Functionby UsingMonoclonalAntibodyProbes

Structural and functional characteristics of Fc receptors for IgG (Fcy) on human neutrophilswere examined with two monoclonal antibody probes specific for the FCV receptors, Leu 11b and 3G8. To determine the distribution, density, and membrane mobility of the Fcy receptor, we used immunogold staining techniques, flow cytometry analysis, and fluorescence microscopy.Both 3G8 and Leu 11b inhibited several cellfunctions,therebydepictingthe regulatoryroleof the Fcy receptor in mediatingneutrophilactivities.Among the functionsstudiedwere release of lysosomalenzymes, releaseof superoxideanion (Ok), and Fc-dependentrosette formation and phagocytosis.The densitiesof Fcy determinantsrecognizedby Leu 11b and 3G8 oncells from a patient with chronic myelogenous leukemia were less than the density of epitopeson neutrophilsfrom a normalindividual.Taken together, the detailedanalysisof physicaland functionalaspectsof the Fcy receptoron neutrophilsdescribedinthisstudyserve as a model for further assessment of the use of Fcy phenotypingof cells as a diagnostictool.