Reduced FcRn-mediated transcytosis of IgG2 due to a missing Glycine in its lower hinge.

Neonatal Fc-receptor (FcRn), the major histocompatibility complex (MHC) class I-like Fc-receptor, transports immunoglobuline G (IgG) across cell layers, extending IgG half-life in circulation and providing newborns with humoral immunity. IgG1 and IgG2 have similar half-lives, yet IgG2 displays lower foetal than maternal concentration at term, despite all known FcRn binding residues being preserved between IgG1 and IgG2. We investigated FcRn mediated transcytosis of V-matched IgG1 and IgG2 and mutated variants thereof lacking Fc-gamma receptor (FcγR) binding in human cells expressing FcRn.

An investigation into IgE-facilitated allergen recognition and presentation by human dendritic cells.

Background: Allergen recognition by dendritic cells (DCs) is a key event in the allergic cascade leading to production of IgE antibodies. C-type lectins, such as the mannose receptor and DC-SIGN, were recently shown to play an important role in the uptake of the house dust mite glycoallergen Der p 1 by DCs. In addition to mannose receptor (MR) and DC-SIGN the high and low affinity IgE receptors, namely FcεRI and FcεRII (CD23), respectively, have been shown to be involved in allergen uptake and presentation by DCs.

Recombinant HPA-1a antibody therapy for treatment of fetomaternal alloimmune thrombocytopenia: proof of principle in human volunteers.

Fetomaternal alloimmune thrombocytopenia, caused by the maternal generation of antibodies against fetal human platelet antigen-1a (HPA-1a), can result in intracranial hemorrhage and intrauterine death. We have developed a therapeutic human recombinant high-affinity HPA-1a antibody (B2G1Δnab) that competes for binding to the HPA-1a epitope but carries a modified constant region that does not bind to Fcγ receptors. In vitro studies with a range of clinical anti-HPA-1a sera have shown that B2G1Δnab blocks monocyte chemiluminescence by >75%.

Developing recombinant HPA-1a-specific antibodies with abrogated Fcgamma receptor binding for the treatment of fetomaternal alloimmune thrombocytopenia.

Fetomaternal alloimmune thrombocytopenia (FMAIT) is caused by maternal generation of antibodies specific for paternal platelet antigens and can lead to fetal intracranial hemorrhage. A SNP in the gene encoding integrin beta3 causes a clinically important maternal-paternal antigenic difference; Leu33 generates the human platelet antigen 1a (HPA-1a), whereas Pro33 generates HPA-1b. As a potential treatment to prevent fetal intracranial hemorrhage in HPA-1a alloimmunized pregnancies, we generated an antibody that blocks the binding of maternal HPA-1a-specific antibodies to fetal HPA-1a1b platelets by combining a high-affinity human HPA-1a-specific scFv (B2) with an IgG1 constant region modified to minimize Fcgamma receptor-dependent platelet destruction (G1Deltanab).

A chimeric antibody to varicella-zoster virus glycoprotein e.

Varicella-Zoster virus (VZV) immune globulin (VZIG) derived from pooled human serum is currently used in immunotherapy of VZV-associated complications of chickenpox and shingles. We developed a mouse-human chimeric antibody against a VZV glycoprotein E (gE) epitope as a safer replacement for VZIG. Variable (V) heavy- and V kappa light-chain exons, derived from an anti-VZV gE antibody secreting mouse hybridoma cell line, were cloned into expression vectors containing an immunoglobulin promoter and enhancer, and human IgG1 or kappa constant (C) region genes.

Differential binding to human FcgammaRIIa and FcgammaRIIb receptors by human IgG wildtype and mutant antibodies.

We are investigating the interactions of recombinant human IgG antibodies with Fc receptors to enable selection of a constant region giving minimal depletion of antigen-bearing cells. Eight variant constant regions were made by substituting motifs between human IgG subclasses in the lower hinge region and/or a specially close loop of the CH2 domain. Mutations in the lower hinge region were shown to eliminate FcgammaRI binding and monocyte activation [Eur.