Release of Fc gamma RIIa2 by activated platelets and inhibition of anti-CD9-mediated platelet aggregation by recombinant Fc gamma RIIa2.
Thrombin-activated human platelets and megakaryocyte cell lines release soluble Fc gamma RII (Fc gamma RIIa2) containing the extracellular and intracellular regions of Fc gamma RIIa1, but lacking the transmembrane domain. Use of polyclonal antibodies directed either against the entire intracytoplasmic tail, or against a peptide located near the C-terminal part of the intracellular region of Fc gamma RIIa2, showed the presence of both a complete form of Fc gamma RIIa2 and a C-terminal truncated form in supernatants of platelets after release of their alpha granule contents and in culture supernatants of megakaryocyte cell lines. Furthermore, recombinant Fc gamma RIIa2 inhibited in a dose-dependent manner Fc-dependent anti-CD9 antibody-induced platelet aggregation. Thus, release of Fc gamma RIIa2 by activated platelets could play an important role in the regulation of platelet activation by immune complexes.
INSERM Unité 311, Centre Régional de Transfusion Sanguine de Strasbourg, France.
C
C
Gachet
A
A
Astier
H
H
de la Salle
C
C
de la Salle
W H
WH
Fridman
J P
JP
Cazenave
D
D
Hanau
J L
JL
Teillaud
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000276:immunology*; D001792:Blood Platelets / Q000276:immunology* / Q000502:physiology; D015153:Blotting, Western; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008533:Megakaryocytes / Q000276:immunology / Q000502:physiology; D008562:Membrane Glycoproteins / Q000276:immunology; D015539:Platelet Activation / Q000187:drug effects; D010974:Platelet Aggregation / Q000276:immunology*; D016133:Polymerase Chain Reaction; D017452:Receptors, IgG / Q000096:biosynthesis* / Q000276:immunology / Q000302:isolation & purification; D011994:Recombinant Proteins / Q000276:immunology; D060245:Tetraspanin 29; D013917:Thrombin / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; C554869:CD9 protein, human; D008562:Membrane Glycoproteins; D017452:Receptors, IgG; D011994:Recombinant Proteins; D060245:Tetraspanin 29; D013917:Thrombin