title: Biomarkers for non-human primate type-I hypersensitivity: antigen-specific immunoglobulin E assays.
abstract: Immunoglobulin E (IgE) is the least abundant immunoglobulin in serum. However, development of an IgE immune response can induce IgE receptor-expressing cells to carry out potent effector functions. A reliable antigen-specific IgE biomarker method for use in non-human primate studies would facilitate (i) confirmation of Type-I hypersensitivity reactions during safety toxicology testing, and (ii) a better understanding of non-human primate models of allergic disease. We cloned and expressed a recombinant cynomolgus monkey IgE molecule in order to screen a panel of commercially available detection reagents raised against human IgE for cross-reactivity. The reagent most reactive to cynomolgus IgE was confirmed to be specific for IgE and did not bind recombinant cynomolgus monkey IgG1-4. A drug-specific IgE assay was developed on the MSD electrochemiluminescent (ECL) platform. The assay is capable of detecting 10 ng/mL drug-specific IgE. Importantly, the assay is able to detect IgE in the presence of excess IgG, the scenario likely to be present in a safety toxicology study. Using our ECL assay, we were able to confirm that serum from cynomolgus monkeys that had experienced clinical symptoms consistent with hypersensitivity responses contained IgE specific for a candidate therapeutic antibody. In addition, a bioassay for mast cell activation was developed using CD34(+)-derived cynomolgus monkey mast cells. This assay confirmed that plasma from animals identified as positive in the drug-specific IgE immunoassay contained biologically active IgE (i.e. could sensitize cultured mast cells), resulting in histamine release after exposure to the therapeutic antibody. These sensitive assays for Type-I hypersensitivity in the NHP can confirm that secondary events are downstream of immunogenicity.
authors.affiliation: Department of Discovery Toxicology, Amgen Inc., Thousand Oaks, CA 91320, United States.
authors.forename: Darcey
authors.initials: D
authors.lastname: Clark
authors.forename: Faith
authors.initials: F
authors.lastname: Shiota
authors.forename: Carla
authors.initials: C
authors.lastname: Forte
authors.forename: Padma
authors.initials: P
authors.lastname: Narayanan
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Mytych
authors.forename: M Benjamin
authors.initials: MB
authors.lastname: Hock
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018952:Antigens, CD34 / Q000276:immunology; D015415:Biomarkers / Q000737:chemistry; D003429:Cross Reactions; D000939:Epitopes; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology; D006969:Hypersensitivity, Immediate / Q000276:immunology*; D007118:Immunoassay / Q000379:methods*; D007073:Immunoglobulin E / Q000737:chemistry* / Q000276:immunology*; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology; D008252:Macaca fascicularis; D008407:Mast Cells / Q000276:immunology; D008969:Molecular Sequence Data; D017455:Receptors, IgE / Q000276:immunology
chemical_list: D018952:Antigens, CD34; D015415:Biomarkers; D000939:Epitopes; D007074:Immunoglobulin G; D017455:Receptors, IgE; D007073:Immunoglobulin E