The glycosyl phosphatidylinositol-linked Fc gamma RIIIPMN mediates transmembrane signaling events distinct from Fc gamma RII.
To investigate the ability of FcgammaRIII(PMN), the GPI-anchored isoform of FcgammaRIII (CD16) in polymorphonuclear leukocytes (PMN), to mediate transmembrane signaling events, we measured changes in membrane potential with DiOC(5) and in intracellular calcium with indo-1. FcgammaR were ligated by anti-FcgammaRIII mAb 3G8 (IgG and Fab), anti-FcgammaRII mAb IV.3 (IgG and Fab), and human IgG aggregates. Cell bound mAbs were also crosslinked by goat F(ab')(2) anti-mouse IgG. 3G8 IgG elicited a rapid change in [Ca(2+)](i), which was unaffected by EGTA, Vibrio cholerae toxin (CT), or Bordetella pertussis toxin (PT), and was abolished by BAPTA . Univalent receptor binding with 3G8 Fab gave no response but crosslinking with F(aV)2 GAM gave a rapid [Ca2,](i) response. Neither IV.3 Fab, IV.3 IgG, nor crosslinking of IV.3 Fab elicited a calcium signal. PI-PLC-treated PMN with the density of FcgammaRIII(PMN) reduced to that of FcgammaRII showed an unattenuated change in [Ca(2+)](i), with a 3G8 stimulus. The effects of IgG aggregates paralleled those of 3G8 mAb. These data indicate that multivalent ligation of FcgammaRIII(PMN) initiates an increase in [Ca(2+)];, derived from intracellular stores, that is distinct from both the FMLP- and FcgammaRII-induced responses. Ligand-dependent interaction with FcgammaRII is not required. Since FcgammaRIII(PMN) can internalize the FcgammaRIII-specific probe Con A-opsonized E and lyse anti-FcgammaRIII heteroantibody-opsonized chick E, this GPI-anchored molecule mediates both signal transduction and integrated cell responses.
Kimberly
R P
RP
Hospital for Special Surgery, Cornell University Medical College, New York, New York 10021.
Ahlstrom
J W
JW
Click
M E
ME
Edberg
J C
JC
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation / Q000502:physiology*; D002118:Calcium / Q000097:blood; D002462:Cell Membrane / Q000187:drug effects / Q000276:immunology / Q000502:physiology; D002634:Chemotaxis, Leukocyte; D005456:Fluorescent Dyes; D006017:Glycolipids / Q000502:physiology*; D017261:Glycosylphosphatidylinositols; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000276:immunology / Q000502:physiology*; D010716:Phosphatidylinositols / Q000502:physiology*; D011961:Receptors, Fc / Q000502:physiology*; D017452:Receptors, IgG; D015398:Signal Transduction; D013050:Spectrometry, Fluorescence
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D005456:Fluorescent Dyes; D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D007074:Immunoglobulin G; D010716:Phosphatidylinositols; D011961:Receptors, Fc; D017452:Receptors, IgG; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002118:Calcium