Application Methods: Flow Cytometry, IHC-Leica® Bond™, Immunohistochemistry (Paraffin), Immunoprecipitation, Western Blotting
Background: FcγRIIB (CD32B) is a low affinity, IgG Fc-binding receptor expressed on B cells, monocytes, macrophages, and dendritic cells (DCs) (1-3). It is the inhibitory Fc receptor and signals through an immunoreceptor tyrosine-based inhibitory motif (ITIM) within its carboxy-terminal cytoplasmic tail (2). Binding of immune complexes to FcγRIIB results in tyrosine phosphorylation of the ITIM motif at Tyr292 and recruitment of the phosphatase SHIP, which mediates inhibitory effects on immune cell activation (2,4). In this way, FcγRIIB suppresses the effects of activating Fc-binding receptors (3). For example, mice deficient for FcγRIIB have greater T cell and DC responses following injection of immune complexes (5, 6). In addition, FcγRIIB plays a role in B cell affinity maturation (7). Signaling through FcγRIIB in the absence of signaling through the B cell receptor (BCR) is proapoptotic, while signaling through FcγRIIB and the BCR simultaneously attenuates the apoptotic signal and results in selection of B cells with higher antigen affinity (7).
Application Methods: IHC-Leica® Bond™, Immunohistochemistry (Paraffin), Western Blotting
Background: Cluster of Differentiation 4 (CD4) is a glycoprotein composed of an amino-terminal extracellular domain (four domains: D1-D4 with Ig-like structures), a transmembrane part and a short cytoplasmic tail. CD4 is expressed on the surface of T helper cells, regulatory T cells, monocytes, macrophages and dendritic cells, and plays an important role in the development and activation of T cells. On T cells, CD4 is the co-receptor for the T cell receptor (TCR), and these two distinct structures recognize the Antigen–Major Histocompatibility Complex (MHC). Specifically, the D1 domain of CD4 interacts with the β2-domain of the MHC class II molecule. CD4 ensures specificity of the TCR–antigen interaction, prolongs the contact between the T cell and the antigen presenting cell and recruits the tyrosine kinase Lck, which is essential for T cell activation (1).
Application Methods: Immunohistochemistry (Paraffin), Immunoprecipitation, Western Blotting
Background: VWF (Von Willebrand factor) is a multimeric plasma glycoprotein that promotes adhesion of platelets to sites of vascular injury (1). Mature circulating VWF is made up of disulfide-bonded multimers that are in a complex with factor VIII (2). VWF is stored in secretory Weibel-Palade bodies in endothelial cells (3,4). It is synthesized as a large precursor protein and undergoes extensive posttranslational modifications including dimerization in the endoplasmic reticulum followed by cleavage of the pro-peptide and multimerization in the Golgi apparatus (3,4). VWF is important in hemostasis, and genetic defects in the structure and modification of VWF can cause von Willebrand disease (VWD), the most common congenital bleeding disorder in humans (5). Alternatively, increased levels of VWF have been shown to be involved in acute coronary thrombosis and are a clinical risk marker for atherosclerosis (6). VWF has also been shown to have a role in inflammation, functioning as an adhesive site for a variety of leukocyte subsets (7). Through siRNA experiments and the use VWF-deficient mice, it has also been shown that VWF regulates angiogenesis (8).