Mechanism of allergic cross-reactions—II. Cross-stimulation, by chemically unrelated ligands, of rat basophilic leukemia cells sensitized with an anti-DNP IgE antibody

Characterization of Modified Allergen Extracts by in vitro β-Hexosaminidase Release from Rat Basophils

“…The RBL cell assay as a murine equivalent of human type I allergic reaction (release of β-hexosaminidase from IgE-sensitized rat basophils upon allergen stimulation) has already been established as an in vitro method not only for characterizing allergenic extracts [24, 25]but also for studying the properties of IgE-mediated release [25, 26, 27]. …”

Comparative docking studies on ligand binding to the multispecific antibodies IgE-La2 and IgE-Lb4

“…This leads to a better understanding of the experimental observation gained by screening essays and subsequent spectroscopic determination of binding constants [10,12] showing that these antibodies bind large sets of ligands in the range of medium and low affinity, which is still of physiological relevance as shown by the stimulation of mediator release [34]. Further support for the results comes from the study of Mian et al [6] who concluded that frequent occurrence of Tyr and Trp residues in the binding site is of major importance for multispecific behaviour.…”

“…Concerning the first point, experimental evidence for multispecific behaviour of antibodies is already available for a considerable amount of systems [6][7][8][9] and models exist which describe the specificity of the immune response, in general, and of the antigenmntibody reaction in particular, as a population-and-threshold phenomenon [12,34,35]. However, little structural information is available upon which an explanation of multispecific behaviour may be based.…”

Mechanism of Allergic Cross-Reactions

“…the cross-stimulation of rat ba sophilic leukemia (RBL-2H3) cells can be affected by structurally dissimilar compounds when the cells are sensi tized with the same multispecific monoclonal IgE [3], Sub sequently, two of the mouse monoclonal IgEs were cloned and sequenced [4], and from the amino acid sequence data 3-D images of the combining regions were reconstructed by computer-aided molecular modeling [5], Based on biophys ical studies and molecular modeling, it was suggested that an overabundance o f solvent-exposed aromatic residues in the.combining regions are responsible for the multispecific Received: November 9,1994 Accepted after revision: April 4. 1995 binding characteristics of these IgEs [5], Although the anti bodies recognized a large number of ligands that were struc turally unrelated to the immunizing haptens [2, 4-dinitrophenol (DNP) or 2 ,4 ,6-trinitrophenol (TNP)], the great ma jority of the interacting compounds found by screening [2] and mediator release [3] were aromatics. And since the li gand-binding regions were found to be irregular aromatic surfaces [5], the multispecific interactions of aromatic li gands could have been interpreted as 'mimicking interac tions' with the involvement of the same DNP-orTNP-binding pockets of these antibodies.…”

“…The purified allergen was kindly provided by Dr. W. R. Thomas (Princess Margrct Hospital, Subiaco, Australia). BSA-(DNP)7 was prepared as described [3]. Induced release of incorporated [3H]serotonin (obtained from Amersham) from RBL-2H3 cells was measured as described [3] with the following modification: optimal allergen and conjugate concentration for sero tonin release was determined in preliminary experiments by adding the allergens or DNP-conjugate in 1:10 serial dilutions; the serotonin release assay was repeated at least twice with allergens added at opti mal concentrations.…”