Anti-FCGR2A monoclonal antibody, clone BU21

The binding and activation of macrophages by microscopic aggregates of oxLDL in the intima of the arteries may be an important step towards atherosclerosis leading to heart attack and stroke. Microbeads coated with oxLDL were used to activate, capture and isolate the oxLDL receptor complex from the surface of live cells. Analysis of the resulting tryptic peptides by liquid chromatography and tandem mass spectrometry revealed the Spleen Tyrosine Kinase (SYK), and many of SYK's known interaction network including Fc receptors (FCGR2A, FCER1G and FCGR1A) Toll receptor 4 (TLR4), receptor kinases like EGFR5, as well as RNA binding and metabolism proteins. High-intensity precursor ions (similar to 9*E3 to 2*E5 counts) were correlated to peptides and specific phosphopeptides from long isoform of SYK (SYK-L) by the SEQUEST, OMSSA and X!TANDEM algorithms. Peptides or phosphopeptides from SYK were observed with the oxLDL-microbeads. Pharmacological inhibitors of SYK activity significantly reduced the engulfment of oxLDL microbeads in the presence of serum factors, but had little effect on IgG phagocytosis. Anti SYK siRNA regulated oxLD engulfment in the context of serum factors and or SYK-L siRNA significantly inhibited engulfment of oxLDL microbeads, but not IgG microbeads. (C) 2016 Elsevier Inc. All rights reserved.

Background: The development of factor (F) VIII neutralizing alloantibodies (inhibitors) is a major complication of treatment with FVIII concentrates in hemophilia A and the etiology is still poorly understood. The low-affinity Fc gamma receptors (Fc gamma R), which are expressed on immune cells, provide an important link between cellular and humoral immunity by interacting with IgG subtypes. Genetic variations of the genes encoding Fc gamma Rs (FCGR genes) have been associated with susceptibility to infectious and autoimmune diseases. Objectives: The aim of this study was to investigate the association between genetic variation of FCGR and inhibitor development in severe hemophilia A. Patients/Methods: In this case-control study samples of 85 severe hemophilia A patients (siblings from 44 families) were included. Single nucleotide polymorphisms and copy number variation of the FCGR2 and FCGR3 gene cluster were studied in an FCGR-specific multiplex ligation-dependent probe amplification assay. Frequencies were compared in a generalized estimating equation regression model. Results: Thirty-six patients (42%) had a positive history of inhibitor development. The polymorphism 131R > H in the FCGR2A gene was associated with an increased risk of inhibitor development (odds ratio [OR] per H-allele, 1.8; 95% confidence interval [CI], 1.1-2.9). This association persisted in 29 patients with high titer inhibitors (OR per H-allele, 1.9; 95% CI, 1.2-3.2) and in 44 patients with the F8 intron 22 inversion (OR per H-allele, 2.6; 95% CI, 1.1-6.6). Conclusions: Hemophilia A patients with the HH genotype of the FCGR2A polymorphism 131R > H have a more than 3-fold increased risk of inhibitor development compared with patients with the RR genotype.