Characterization of Fc gamma receptors on human megakaryocytes.
Thromb Haemost
; 75(4): 661-7, 1996 Apr.
Article
em En
| MEDLINE
| ID: mdl-8743196
ABSTRACT
Megakaryocyte and platelet Fc gamma receptors (FcR) are of importance in the pathophysiology of immune complex-mediated thrombocytopenias such as heparin-induced thrombocytopenia. In this study, Fc gamma R proteins and mRNAs in normal human megakaryocytes were examined. Fc gamma R proteins were studied with immunocytochemical staining, dual colour flow cytometry and immunoprecipitation using monoclonal antibodies against Fc gamma R I, Fc gamma R II and Fc gamma R III. Fc gamma R mRNAs were measured with biotinylated cDNA of oligonucleotide probes using a novel quantitative in situ hybridization technique. Using these techniques, Fc gamma R II protein and mRNA, but not Fc gamma R I and Fc gamma R III proteins and transcripts were detected in megakaryocytes. Further, transcript analysis showed that megakaryocytes contain only the transcript of Fc gamma R IIA gene but no transcripts of Fc gamma R IIB nor Fc gamma R IIC genes; Fc gamma R IIA transcripts with and without the transmembrane (TM) exon are present in approximately equal proportions. In contrast, neutrophils and macrophages also contain Fc gamma R IIA transcript but Fc gamma R IIA transcript with the TM exon predominates suggesting cell lineage-specific Fc gamma R IIA expression. Fc gamma R IIA transcript lacking the TM exon predicts the presence of a potential soluble form of Fc gamma R in platelets and megakaryocytes which may have a physiological role as it can compete with the membrane-bound Fc gamma R IIA for binding of IgG-containing immune complexes and thus protect these cells from excessive binding and injurious effects of immune complexes.
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Base de dados:
MEDLINE
Assunto principal:
RNA Mensageiro
/
Megacariócitos
/
Receptores Fc
/
Éxons
Limite:
Humans
Idioma:
En
Ano de publicação:
1996
Tipo de documento:
Article