Immunoglobulin Fc receptor

Fc Crystallizable fraction of immunoglobulin molecule Fey Receptor for Fc portion of IgG FeyRI Ig Fc receptor I also known as CD64... 

Figure 1.4. Recognition of bacteria by neutrophils. Invading bacteria are opsonised by serum proteins, such as complement fragments (e.g. C3b) and immunoglobulins. The plasma membranes of neutrophils possess receptors for these opsonins (e.g. Fc receptors and complement receptors). Thus, occupancy of these opsonin receptors triggers phagocytosis and activates events such as the respiratory burst and degranulation. Note that the receptors and opsonins are not drawn to scale.

Rosales, C., Brown, E. J. (1992). Signal transduction by neutrophil immunoglobulin G Fc receptors. Dissociation on intracytoplasmic calcium concentration rise from inositol 1,4,5-trisphosphate. J. Biol. Chem. 267, 5265-71. 

Other uptake-linked receptors found on the SECs are the Fc receptor for the uptake of immunoglobulins [19], the CD14 receptor for the binding of lipopolysaccharide (EPS) bound to EPS binding protein [20], the platelet derived growth factor AA receptor [21] and the glucagon receptor [22]. 

In the case of immunoglobulin, microarray data indicated the opposite effect that the Fc-receptor is elevated in chronic MS but not in acute lesions. Using Fcy-receptor knockout mice, the disease was found to be absent. Inter-venous immrmoglobulin therapy in the EAE mouse model was reported (see Lock, 2002, Reference 29). In summary. Lock et al. were able to apply the results of microarray-based gene expression clustering of a human disease pathological state (acute vs. chronic MS) to successfully identify fherapeutic targets for an animal model (EAE) potentially applicable to the human condition. 

Binstadt BA, Geha RS, Bonilla FA. IgG Fc receptor polymorphisms in human disease implications for intravenous immunoglobulin therapy. J Allergy Clin Immunol 2003 697-703. 

Weng WK, Rosenberg A, Levy R. Immunoglobulin G Fc receptor polymorphisms and clinical course in follicular lymphoma patients. Blood2004 104 887a. 

Weng WK, Czerwinski D, Timmerman J et al. Clinical outcome of lymphoma patients after idiotype vaccination is correlated with humoral immune response and immunoglobulin G Fc receptor genotype. J Clin Oncol 2004 22 4717 724. 

Fluorochrome-labeled anti-immunoglobulin antibody labeled F(ab )2 fragments should be selected for target cells that express Fc receptors... 

Another potential source of cross-reactivity is the presence of Fc receptors in cells or tissues, which bind the Fc region of the primary or secondary antibodies. These nonspecific sites can be blocked with normal serum or nonimmune immunoglobulins. When a secondary antibody is used for detection, the normal serum or immunoglobulin for blocking should be from the same species as the secondary antibody. 

Such a control antibody is known as an isotype control because it is of the same immunoglobulin isotype (subclass) as the staining antibody used in the experiment. It will allow you to determine how much background stain is due to irrelevant stickiness (dead cells, Fc receptors, and so forth). The only trouble with this scenario is that exactly correct isotype controls are not usually available. Various manufacturers of monoclonal antibodies will sell so-called isotype controls and will certainly recommend that they be used. These are, however, general purpose isotype controls that will be of an average... 

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