Human IgG Fc receptors

I A Heijnen1, J G van de Winkel

  • 1Department of Immunology and Medarex Europe BV, G04.614, University Hospital Utrecht, The Netherlands.

Human IgG receptors constitute a family of glycoprotein complexes consisting of ligand-binding, and associated signaling chains. Three leukocyte classes (Fc gamma RI, II, and III) and one separate endothelial Fc gamma R class (FcRB) are defined which are expressed on hematopoietic and endothelial cells. Upon interaction with IgG, Fc gamma R initiate a plethora of signaling cascades involving receptor signaling motifs, and protein tyrosine kinases and phosphatases. These cascades ultimately culminate in activation or deactivation of effector cells, resulting in initiation or down-modulation of cellular processes. Recent evidence points to a crucial in vivo role of Fc gamma R in both initiation and regulation of inflammatory and cytotoxic responses. These Fc gamma R-mediated immune responses can be exploited to develop novel immunotherapies.

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