Fc Portion (fc + portion)

Distribution by Scientific Domains

Selected Abstracts

Binding site on human immunoglobulin G for the affinity ligand HWRGWV

Haiou Yang
Abstract Affinity ligand HWRGWV has demonstrated the ability to isolate human immunoglobulin G (hIgG) from mammalian cell culture media. The ligand specifically binds hIgG through its Fc portion. This work shows that deglycosylation of hIgG has no influence on its binding to the HWRGWV ligand and the ligand does not compete with Protein A or Protein G in binding hIgG. It is suggested by the mass spectrometry (MS) data and docking simulation that HWRGWV binds to the pFc portion of hIgG and interacts with the amino acids in the loop Ser383,Asn389 (SNGQPEN) located in the CH3 domain. Subsequent modeling has suggested a possible three-dimensional minimized solution structure for the interaction of hIgG and the HWRGWV ligand. The results support the fact that a peptide as small as a hexamer can have specific interactions with large proteins such as hIgG. Copyright 2009 John Wiley & Sons, Ltd. [source]

Combining etanercept with traditional agents in the treatment of psoriasis: a review of the clinical evidence

PA Foley
Abstract Psoriasis is a chronic, systemic inflammatory disorder manifesting primarily in skin and potentially in joints, frequently necessitating treatment with conventional systemic therapies, phototherapy or biological agents. Patients with moderate to severe disease suffer a diminished quality of life, experience significant comorbidities and have a higher mortality. Although traditional treatments are effective in the short-term, their use is often limited by concerns over long-term toxicity, including end-organ damage and risk of malignancy. Combination therapy is a commonly used approach and is often more effective than any single agent. Lower doses of two treatments in combination can also minimize potential side effects from a single agent at higher doses. Etanercept is a recombinant human tumour necrosis factor (TNF), receptor (p75) protein fused with the Fc portion of IgG1 that binds to TNF,. This article reviews the evidence on the efficacy and safety of etanercept in combination with methotrexate, acitretin, narrowband UVB and cyclosporin. The largest body of evidence assesses the combination with methotrexate, although evidence is available for the other combinations. Data suggest that although highly effective as monotherapy, etanercept in combination with a conventional systemic agent can enhance efficacy and allow drug sparing. Potentially, the combination may also result in faster treatment responses and permit safe transitioning from one systemic agent to another. Evidence to date suggests that these benefits can be achieved without significant additional toxicity, although long-term data on the efficacy and safety of the combination in psoriatic populations is limited and further evaluation is warranted. [source]

Fusion protein consisting of the first immunoglobulin-like domain of porcine nectin-1 and Fc portion of human IgG1 provides a marked resistance against pseudorabies virus infection to transgenic mice

Yukiko Tomioka
ABSTRACT Nectin-1 is a Ca2+ -independent Ig-like cell,cell adhesion molecule and an alphaherpesvirus receptor that binds to virion glycoprotein D by the first Ig-like domain. We have investigated the antiviral potentials of soluble forms of porcine nectin-1 to PRV infection by generating transgenic mice expressing different types of fusion protein. Previously, we reported that mice transgenic for a chimera that carried the entire ectodomain of porcine nectin-1 fused to the Fc portion of porcine IgG1 were more resistant than those transgenic for a chimera that carried the first Ig-like domain fused to the Fc portion. Recently, we generated transgenic mice expressing a fusion protein made of the first Ig-like domain fused to the Fc portion of human IgG1, and reported that they showed a microphthalmia. Here, two transgenic mouse lines expressing the fusion protein were challenged with PRV for comparing their resistances with those of transgenic mice expressing different types of fusion protein. Surprisingly, both transgenic mouse lines showed a high resistance to the viral infection, especially via the i.n. route. Significant resistance of the embryonic fibroblasts was also observed. Altogether, these findings indicated that the fusion protein consisting of the first Ig-like domain fused to the human Fc portion provided a marked resistance against PRV infection to the transgenic mice. [source]

Interindividual variability in the concentration,effect relationship of antilymphocyte globulins,a possible influence of Fc,RIIIa genetic polymorphism

David Ternant
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT ,,There is interindividual variability in the antilymphocyte globulin (ALG) effect, but there is no pharmacokinetic,pharmacodynamic study of this subject. ,,In addition, a time dependence of the pharmacokinetics of some therapeutic antibodies has been described. ,,ALGs may partly act by antibody-dependent cellular cytotoxicity (ADCC), but their mechanism of action in humans is not known. WHAT THIS STUDY ADDS ,,Horse ALG pharmacokinetics can be described using a two-compartment model with time-dependent central volume of distribution. ,,After an initial concentration-independent lymphocyte depletion, the concentration,effect relationship can be described using a physiological indirect response model. ,,The genetic polymorphism of Fc,RIIIa at position 158 may influence the ALG concentration,effect relationship and these polyclonal antibodies may therefore act by ADCC. AIMS Polyclonal antilymphocyte globulins (ALGs) are currently used in transplantation, but the sources of interindividual variability of their effect are poorly understood. No pharmacokinetic,pharmacodynamic (PK,PD) study of ALG is available. Moreover, the genetic polymorphism of Fc,RIIIa, a receptor for the Fc portion of immunoglobulins involved in antibody-dependent cellular cytotoxicity (ADCC), may influence their concentration,effect relationship. METHODS Fourteen kidney transplant patients treated by horse ALG were included in a prospective, noncomparative study. A population two-compartment PK model including a time dependence of the central volume of distribution was developed. Total lymphocyte count was used as biomarker of effect. Concentration,effect data were described using a physiological indirect response model, combining concentration-dependent and -independent inhibitions of lymphocyte input into the circulation. In addition, six kidney transplant patients in whom ALG concentrations were not available were included retrospectively. All patients were genotyped for FCGR3A. RESULTS Both the PK and the PK,PD model described the data satisfactorily and showed high interindividual variability. Asymptotic T1/2 -, and T1/2 -,-values were 1.3 and 25 days, respectively. The concentration of ALG leading to a 50% inhibition of lymphocyte input (IC50) was lower in FCGR3A- V carriers than in FCGR3A- F/F patients (383 199 vs. 593 209 mg l,1, P = 0.008). CONCLUSIONS This is the first description of the ALG effect on lymphocyte count using PK,PD modelling. Our results show that part of the variability in their concentration,effect relationship may be explained by Fc,RIIIa genetic polymorphism and therefore that horse ALG may deplete lymphocytes by ADCC. [source]

Engineering therapeutic monoclonal antibodies

Xiao-yun Liu
Summary: During last two decades, the chimerization and humanization of monoclonal antibodies (mAbs) have led to the approval of several for the treatment of cancer, autoimmune diseases, and transplant rejection. Additional approaches have been used to further improve their in vivo activity. These include combining them with other modalities such as chemotherapy and redesigning them for improved pharmacokinetics, effector function, and signaling activity. The latter has taken advantage of new insights emerging from an increased understanding of the cellular and molecular mechanisms that are involved in the interaction of immunoglobulin G with Fc receptors and complement as well as the negative signaling resulting from the hypercrosslinking of their target antigens. Hence, mAbs have been redesigned to include mutations in their Fc portions, thereby endowing them with enhanced or decreased effector functions and more desirable pharmacokinetic properties. Their valency has been increased to decrease their dissociation rate from cells and enhance their ability to induce apoptosis and cell cycle arrest. In this review we discuss these redesigned mAbs and current data concerning their evaluation both in vitro and in vivo. [source]