Activation of human monocytes and granulocytes by monoclonal antibodies to glycosylphosphatidylinositol-anchored antigens.
The present study investigated possible receptor-like characteristics of glycosylphosphatidylinositol (GPI)-linked antigens on human monocytes and granulocytes by measuring cytoplasmic calcium fluxes and the oxidative burst in cells following cross-linking of GPI-linked antigens. Cross-linking of cell-bound anti-CD14, -CDw52 and -CD55 induced cytoplasmic calcium fluxes and oxidative bursts in unprimed human monocytes similar to those observed following Fc gamma R cross-linking. In granulocytes primed with 200 mM N-formyl-Met-Leu-Phe (FMLP), cross-linking of cell-bound anti-CD16, -CD24, -CD59 and -CD67 led to calcium fluxes and activation of the oxidative burst. The oxidative bursts mediated by GPI-linked antigens were stronger than those induced by 200 nM FMLP, even though FMLP induced a larger increase in cytoplasmic calcium concentration. The responses were likely to be independent of Fc gamma R interactions as F(ab')2 fragments of IgG or IgM antibodies were used in the experiments. Activating effects of monoclonal antibody to GPI-linked antigens were not observed in cells from patients with paroxysmal nocturnal hemoglobinuria, which are deficient in GPI-linked antigens. In addition, treatment with GPI-specific phospholipase C led to inhibition of cell activation through GPI-linked antigens but not through transmembrane receptors. Cross-linking of a number of non-GPI-linked antigens (CD11a, CD18, CD31, CD35, CD43, and CD45) neither induced calcium fluxes, nor activated the oxidative burst. The results indicate that most, if not all, GPI-linked surface glycoproteins on myeloid cells are capable of mediating cell activation and suggest that the GPI anchor is a structure facilitating signal transduction.
Lund-Johansen
F
F
Department of Pathology, Gade Institute, University of Bergen, Haukeland Hospital.
Olweus
J
J
Symington
F W
FW
Arli
A
A
Thompson
J S
JS
Vilella
R
R
Skubitz
K
K
Horejsi
V
V
D000328:Adult; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D003432:Cross-Linking Reagents; D017261:Glycosylphosphatidylinositols / Q000276:immunology*; D006098:Granulocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D006457:Hemoglobinuria, Paroxysmal / Q000276:immunology / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D008875:Middle Aged; D009000:Monocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D010727:Phosphoric Diester Hydrolases / Q000494:pharmacology; D016897:Respiratory Burst
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D003432:Cross-Linking Reagents; D017261:Glycosylphosphatidylinositols; D010727:Phosphoric Diester Hydrolases; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D002118:Calcium