Hans Bennich

Structure and Function of Human Immunoglobulin E

Publisher Summary This chapter discusses the isolation, and the physicochemical characteristics of immunoglobulin E (IgE) properties of antigenically and biologically active structural regions of IgE, levels of IgE in disease, and detection of antibody activity in the IgE Class. IgE represents a minor, but a distinct class of proteins present in the serum of man and higher primates, and possibly also in the serum of other species. The detection and quantitation of IgE require very sensitive methods. Immunoglobulin E is elevated 4-30 times normally in various diseases, among which atopic disorders and parasitic infestations appear to be the most prominent. Pathological amounts of IgE have also been found in the serum of patients with γE myeloma. The best way to determine IgE is to use the immunochemical methods based upon the reaction between IgE and the antibodies specific for the class-related antigenic determinants of IgE. Gel diffusion methods, such as single radial diffusion in gel are handicapped by low sensitivity; radioimmune assays have proven to be superior.

In vitro Diagnosis of Atopic Allergy

In 96 children with symptoms of asthma or allergic rhinoconjunctivitis, 503 provocation tests with some common allergens (animal danders, pollens, house dust) were performed and the results were compa

Interaction of Human Polyclonal IgE and IgG from Different Species with Protein A from Staphylococcus aureus: Demonstration of Protein-A-reactive Sites Located in the Fab2 Fragment of Human IgG

The peptic fragments F(ab′)2 and Fc″ of human polyclonal IgE were tested by the SpA‐IgE radioimmunoassay for interaction with protein A from Staphylococcus aureus. The Fab″2ɛ fragment but nut the Fc″ɛ fragment retained the ability to react with protein A. IgG preparations from different species were tested for their capacity to inhibit the reaction between 125I‐IgE and protein A. IgG preparations from man and the dog, pig, guinea‐pig and rhesus monkey were all potent inhibitors whereas those from the rabbit, rat, sheep, horse, cow, goat and mouse were very poor inhibitors. The inhibition of the binding of 125I‐IgE to protein A by Fab′2γ fragments, but not by Feγ fragments, suggests a novel type of interaction of protein A with immunoglobulins.

Structure-Function Relationships in Human Immunoglobulin E

The current interest in IgE has evolved from the discovery that antibodies of this minor class of immunoglobulin carry the biological, immunochemical and physical characteristics of reaginic antibodies. The important property of IgB antibodies which allows them to mediate Type I immediate hypersensitivity is their ability to bind reversibly with high affinity to specific membrane receptors on basophils and mast cells. Combination of specific cell-bound antibody with antigen triggers a series of events which ultimately leads to the release of vasoactive amines and other pharmacologically active substances responsible for the clinical manifestations of hypersensitivity. The nature of these intracellular events is poorly understood. Indeed a substantial number of people may ask why these events need exist at all, particiilarly when they are suffering through the ragweed or other airborne-antigen season! In other words the physiological importance of IgE is not known, although it has been implicated in resistance to parasitic infestation.

Anti-IgE antibodies in human serum: occurrence and specificity.

An IgG type of antibody directed against IgE has been studied in serum from healthy and allergic individuals. The technique used is based on adsorption of the IgG fraction in serum to protein A-Sepharose followed by reacting any specific antibody with 125I-IgE. The anti-IgE antibodies were partially blocked by endogenous IgE, indicating the presence of IgE-containing immune complexes in serum. Heating of serum to 56 degrees C disrupted the immune complexes, thereby facilitating the detection of anti-IgE antibodies. The antibodies were essentially directed against the heat-labile D epsilon 2 antigen. Significantly raised (p less than 0.001) levels of anti-IgE antibodies were found in patients suffering from allergic asthma, as compared with non-allergic blood donors.

In vitro Estimation of Allergens by a Radioimmune Antiglobulin Technique Using Human IgE Antibodies

A radioimmune method based on detection of IgE antibodies (RAST) has been used for allergen quantitation, both as a direct test and as an inhibition test. Commercially available allergen extracts from

Analysis of the Serum IgE Levels in Nonimmunized Rats of Various Strains by a Radioimmunoassay

An assay, the paper radioimmunosorbent test (PRIST) for the measurement of total serum IgE in the rat, that allows the measurement of IgE down to a level of 0.25 ng/ml, is described. With this assay it has been demonstrated that significant differences exist in normal serum IgE levels in non‐immunized rats. These differences are strain‐dependent, and strains may be classified as to low (<50 ng/ml), medium (50–300 ng/ml) or high (>300 ng/ml) serum levels. The serum IgE level is not sex‐dependent. Environmental factors have a pronounced influence, optimal housing conditions resulting in low and stable levels while suboptimal conditions result in high levels with great fluctuations. Hybridization experiments suggest a multigenic control, with low IgE strains having a dominating suppressor effect.

Studies on the stability of diluted allergen extracts using the radioallergosorbent test (RAST)

Allergen extracts from birch pollen, timothy pollen and horse dandruff were investigated. The influence of storage time, volume of extract in the vial and various additives on the potency of diluted extracts was tested with the radioallergosorbent test (RAST). The potency of diluted pollen extracts was found to decrease more rapidly than the potency of diluted dandruff extracts. The differences in allergen activity seen in RAST between freshly diluted extracts and stored extract dilutions were roughly reproducible in skin tests and histamine release tests from passively sensitized chopped human lung. The higher allergen stability of the dandruff extracts could, at least in part, be explained by the higher protein content of these extracts. An adsorption of allergen to the glass wall was shown to be the most probable cause to the more rapid decrease of allergen activity seen in pollen extracts stored in vials only partly filled. With addition of 0.2% Tween 20 after storage the potency of the extracts became almost equivalent to that of corresponding dilutions stored in filled vials.

Human Antibodies to Bovine γ-Globulin

Antibodies to bovine γ -globulin (anti-BGG antibodies) were detectable by a radio-immunoassay in 70% of healthy blood donors but, generally, the titres were low. Significantly increa

Evaluation of basic serum IgE levels and the IgE antibody response in the rat by radioimmunoassays.

Interest in the IgE-mast cell system has mainly focused on its role in allergic reactions, an understandable emphasis, in view of the negative effects and the high frequencies of allergic diseases (Johansson et al. 1972, Ishizaka & Ishizaka 1975). The discovery of plasma cell tumors secreting IgE myeloma proteins in the human (Johansson & Bennich 1967) has greatly advanced the development of radioimmunological assays for serum IgE (Johansson et al. 1968) and for the in vitro diagnosis of allergy (Wide et al. 1967) and, in addition, provided the means for studying the covalent structure (Bennich ct al. 1978a) and conformation al properties of the IgE molecule (Dorrington & Bennich 1978). There are, however, reasons to believe that the IgE-mast cell system has a normal function of definite survival value, as the system is to be found in most vertebrate species. This normal function is of considerable interest to us and our present research is aimed at determining the regulatory mechanisms controlling IgE production and elucidating the possible roles that IgE and the mast cell system may play in relation to other classes of humoral antibody and to the functions of macrophages and T and B lymphocytes in developing and regulating a normal immune response. For these studies an animal model system is required which permits not only qualitative but also quantitative measurements at both the cellular and molecular level. Until the recent discovery of IgE producing plasma cell tumors in the rat by Bazin et al. (1974), man was the only species in which this condition had been foimd. This discovery therefore represents an important