title: In vitro basophil histamine-releasing activity of circulating IgG1 and IgG4 autoanti-IgE antibodies from asthma patients and the demonstration that anti-IgE modulates allergen-induced basophil activation.
abstract: In this study we have examined the relationship between the in vitro basophil histamine-releasing activity of human IgG anti-IgE, isolated as euglobulin fractions from sera of asthmatic patients, and its IgG1/IgG4 subclass distribution. In particular, we have investigated whether IgG anti-IgE modulates allergen-induced basophil activation. The study has revealed that only a small proportion of IgG anti-IgE samples triggered histamine release from basophils of an asthmatic individual (4/21; 19%), a hay fever sufferer (4/10; 40%) and a healthy person (7/21; 33%). The basophil histamine-releasing activity of IgG anti-IgE did not seem to be determined by the IgG1/IgG4 subclass composition of the IgG anti-IgE preparation used. Furthermore, we have demonstrated that autoanti-IgE antibodies modulate allergen-induced basophil histamine release. The three modulatory effects exerted by IgG anti-IgE antibodies on allergen-triggered basophil activation (i.e. additive, synergistic and blocking) were not dependent on the subclass nature of IgG anti-IgE or the use of histamine-releasing anti-IgE preparations. Our data suggest that IgG anti-IgE antibodies in asthma patients may consist of two functionally distinct subpopulations: those which up-regulate (pro-allergic) and those which down-regulate (anti-allergic) the allergic release of mediators from mast cells and basophils.
authors.affiliation: Department of Immunology, University of Nottingham Medical School, UK.
authors.forename: F
authors.initials: F
authors.lastname: Shakib
authors.forename: S J
authors.initials: SJ
authors.lastname: Smith
mesh_terms: D000485:Allergens / Q000276:immunology*; D000818:Animals; D039741:Antigens, Dermatophagoides; D001249:Asthma / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D001491:Basophils / Q000276:immunology*; D005260:Female; D006023:Glycoproteins / Q000276:immunology; D006636:Histamine Release / Q000276:immunology*; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D007074:Immunoglobulin G / Q000145:classification / Q000276:immunology*; D008297:Male; D051379:Mice; D008925:Mites / Q000276:immunology; D011058:Pollen / Q000276:immunology; D012712:Serum Globulins / Q000276:immunology
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D001323:Autoantibodies; D006023:Glycoproteins; D007074:Immunoglobulin G; D012712:Serum Globulins; D007073:Immunoglobulin E