Carbenes with reduced heteroatom stabilization: a computational approach.

High-level DFT calculations, coupled with appropriate isodesmic reactions, are employed to investigate the effects of monoheteroatom substitution, cyclization, and unsaturation on the stability, multiplicity, and reactivity of amino-, oxy-, silyl-, phosphino-, and thioalkylcarbenes. The results of these calculations are compared to those of di-tert-butylcarbene, 2,2,5,5-tetramethylcyclopentanylidene, and 2,2,5,5-tetramethylcyclopent-3-enylidene as the reference molecules. The calculated singlet-triplet energy gaps (DeltaE(S-T)) demonstrate the following trend: (amino approximately = oxy) > thio > phosphino > alkyl > silyl. In contrast to the previous reports, isodesmic reactions show that pi-donor/sigma-acceptor amino substituents stabilize not only the singlet but also the triplet states. The stabilization of the triplet states by amino substitution is much less than the singlet states. The DeltaE(S-T) values of all the carbenes are increased through cyclization, while the introduction of unsaturation causes small and rather random changes. These changes are carefully probed by means of isodesmic reactions for the singlet and triplet states, separately. The reactivity of the species is discussed in terms of nucleophilicity, electrophilicity, and proton affinity issues showing amino- and phosphinoalkylcarbenes to be more nucleophilic, more basic, and less electrophilic than oxy- and thioalkylcarbenes, respectively. This detailed study offers new insights into the chemistry of these novel carbenes.

Differential protein expression by dendritic cells from atopic and non-atopic individuals after stimulation by the major house dust mite allergen Der p 1.

BACKGROUND: Dendritic cells (DCs) are sentinels of the immune system and are known to play a key role in allergic responses. However, it is not clear how DCs that have been exposed to an allergen support Th2 type immune responses. It is possible that DCs from atopic individuals are inherently programmed to support allergic disease, or it is the exposure of dendritic cells to allergens that is key to the development of allergic sensitisation. METHODS: We used 2D gel electrophoresis and MALDI mass spectrometry to compare the proteome of DCs from atopic and non-atopic individuals in both the resting state and after stimulation with the major house dust mite allergen Der p 1. RESULTS: Our data show that unstimulated DCs from atopic and non-atopic individuals are very similar at the whole cell proteome level, showing few differentially expressed proteins. However, upon stimulation with Der p 1, a number of additional proteins are differentially expressed, and of these several were of potential relevance to Th2 cell differentiation and the allergic response, including GTP-binding regulatory protein Gi alpha-2, frabin and cathepsin D. CONCLUSION: Whilst there are inherent differences between DCs from atopic and non-atopic individuals, it seems that exposure to allergen plays a key role in differential expression of proteins by these key immune cells. Further studies should now focus on establishing the biological relevance of these proteins as biomarkers in house dust mite allergy and their role in allergen induced Th2 cell differentiation.

An immunoglobulin E-reactive chimeric human immunoglobulin G1 anti-idiotype inhibits basophil degranulation through cross-linking of FcepsilonRI with FcgammaRIIb.

BACKGROUND: IgE binds to mast cells and basophils via its high-affinity receptor, FcepsilonRI, and cross-linking of FcepsilonRI-bound IgE molecules by allergen leads to the release of allergic mediators characteristic of type I hypersensitivity reactions. Previous work has shown that cross-linking of FcepsilonRI with FcgammaRIIb, an ITIM-containing IgG receptor, leads to inhibition of basophil triggering. 2G10, a chimeric human IgG1 anti-idiotype, has broad reactivity with human IgE and as such has the potential to bind simultaneously to FcepsilonRI-bound IgE, via its Fab regions, and the negative regulatory receptor, FcgammaRIIb, via its Fc region. OBJECTIVE: To assess the ability of human 2G10 to inhibit anti-IgE and allergen-driven basophil degranulation through cross-linking of FcepsilonRI-bound IgE with FcgammaRIIb. METHODS: 2G10 was assessed for its ability to bind to FcgammaRIIb on transfected cells and on purified basophils. In the basophil degranulation assay, basophils were purified from peripheral blood of atopic individuals and activated with either anti-IgE or the house dust mite allergen Der p 1, in the presence or absence of human 2G10. Basophil activation was quantified by analysis of CD63 and CD203c expression on the cell surface, and IL-4 expression intracellularly, using flow cytometery. RESULTS: Human 2G10 was able to bind to FcgammaRIIb on transfected cells and on purified basophils, and induce a dose-dependent inhibition of both anti-IgE and Der p 1-driven degranulation of basophils. CONCLUSION: The inhibition of basophil degranulation by the human IgG1 anti-idiotype 2G10 highlights the therapeutic potential of IgE-reactive IgG antibodies in restoring basophil integrity through recruitment of the inhibitory receptor FcgammaRIIb.

The protease allergen Der p 1 cleaves cell surface DC-SIGN and DC-SIGNR: experimental analysis of in silico substrate identification and implications in allergic responses.

BACKGROUND: The cysteine protease Der p 1 from the house dust mite Dermatophagoides pteronyssinus is one of the most potent allergens known. An attractive mechanism for a component of Der p 1 allergenicity lies in its ability to cleave key regulatory molecules from leucocyte surfaces, subverting cellular function and driving abnormal immunoglobulin E (IgE) responses. OBJECTIVE: Although CD23, CD25 and CD40 have already been identified as major Der p 1 targets, other significant substrates may also exist. METHODS: To investigate this, knowledge of the proteolytic properties of Der p 1 was used to perform in silico digestion of human dendritic cell surface proteins, using the prediction of protease specificity (PoPS) bioinformatics tool, in conjunction with cellular in vitro analysis and cleavage site determination. RESULTS: Targets identified included DC-SIGN and DC-SIGNR, two C-type lectins implicated mostly in pathogen trafficking. Treatment of positively expressing cells with Der p 1 led to loss of detectable surface DC-SIGN and DC-SIGNR. Digestion of purified soluble recombinant DC-SIGN and DC-SIGNR, followed by N-terminal sequencing and MALDI mass spectrometry, indicated in each case one major cleavage site and several minor sites, the former correlating well with Der p 1 enzymology and the folded state of the substrate proteins. Loss of DC-SIGN from the cell surface led to reduced binding of intracellular adhesion molecule-3, an endogenous DC-SIGN ligand expressed on naïve T cells which is thought to be involved in T-helper type 1 cytokine signalling. CONCLUSION: These data provide evidence of lectin involvement in the initiation of the allergic response and the value of using genome-wide in silico digestion tools.

Proteolytic activity of the house dust mite allergen Der p 1 enhances allergenicity in a mouse inhalation model.

BACKGROUND: We have recently demonstrated that intraperitoneal immunization of mice with proteolytically active Der p 1, the major house dust mite allergen, results in a significant and selective enhancement of total and Der p 1-specific IgE synthesis compared to mice immunized with proteolytically inactive Der p 1. OBJECTIVE: To investigate whether the proteolytic activity of Der p 1 would lead to enhanced inflammatory cellular infiltration of the lungs and systemic IgE production when administered through the respiratory system, which is the natural route of entry for this allergen. METHODS: Groups of mice were initially sensitized with proteolytically active Der p 1 through the intraperitoneal and the subcutaneous routes and subsequently exposed intranasally to either proteolytically active Der p 1, inactive Der p 1 or PBS. The extent of cellular infiltration of the lungs and systemic IgE production in the three animal groups were then compared. RESULTS: Here, we show for the first time that the administration of proteolytically active Der p 1 to mice through the intranasal route leads to significant inflammatory cellular infiltration of the lungs and systemic production of IgE. CONCLUSIONS: These data underline the important role of the proteolytic activity of Der p 1 in driving the allergic response in the lungs.

The proteolytic activity of the major dust mite allergen Der p 1 conditions dendritic cells to produce less interleukin-12: allergen-induced Th2 bias determined at the dendritic cell level.

BACKGROUND: The proteolytic activity of the house dust mite allergen Der p 1 has recently been shown to bias Th cell subset development in favour of Th2. Apart from its direct effect on T cells, it is conceivable that the proteolytic activity of Der p 1 may induce the generation of dendritic cells (DCs) that favour a Th2 response. OBJECTIVE: To study the effect of the proteolytic activity of Der p 1 on DC functions; namely cell surface phenotype, IL-12 production and ability to favour a Th2 response. METHODS: We have generated immature DCs from peripheral blood monocytes, matured them with LPS in the presence of either proteolytically active or inactive Der p 1 and compared their functions using flow cytometric analysis. RESULTS: Here we demonstrate for the first time that DCs that have been matured in the presence of proteolytically active Der p 1 produce significantly less IL-12, compared to DCs that have been matured in the presence of proteolytically inactive Der p 1. The suppression of IL-12 production was due to the cleavage of CD40 by the proteolytic activity of Der p 1, hence rendering the DCs less responsive to stimulation through the CD40L-CD40 pathway. Furthermore, we demonstrate that DCs that have been matured in the presence of proteolytically active Der p 1 induce the production of significantly less IFN-gamma and more IL-4 by CD4 T cells, compared to DCs that have been matured in the presence of proteolytically inactive Der p 1. CONCLUSIONS: Collectively, our data provide compelling evidence for the role of the proteolytic activity of Der p 1 in directing DCs to induce Th2 subset development.

The production and characterisation of a chimaeric human IgE antibody, recognising the major mite allergen Der p 1, and its chimaeric human IgG1 anti-idiotype.

BACKGROUND: Two mouse monoclonal antibodies have been described, namely: mAb 2C7 (IgG2bkappa), which is directed against the major house dust mite allergen Der p 1, and mAb 2G10 (IgG1kappa), which is an anti-idiotypic antibody raised against mAb 2C7. Given its broad IgE specificity, anti-idiotype mAb 2G10 could potentially have immunomodulatory applications. For example, a chimaeric human IgG version of mAb 2G10 could prove to be a useful molecule for binding to mast cell and basophil FcepsilonRI bound IgE, and in doing so co-ligating FcepsilonRI with FcgammaRIIB, which has been reported to have downregulatory effects. AIMS: To produce a chimaeric human IgE version of mAb 2C7 (mAb 2C7huE) and a chimaeric human IgG1 version of its anti-idiotype mAb 2G10 (mAb 2G10huG1). METHODS: The Vkappa and VH regions of mAb 2C7 and its anti-idiotype mAb 2G10 were engineered into human constant regions of the IgE and IgG1 isotypes, respectively. RESULTS: The production of chimaeric mAb 2C7huE and its anti-idiotype mAb 2G10huG1 confirmed that the respective mouse antibody V regions were successfully engineered into human constant regions and still retained the specificity of the original murine V regions. CONCLUSION: The newly constructed chimaeric antibodies will be useful to investigate the downregulation of IgE mediated hypersensitivity by the crosslinking of FcepsilonRI with FcgammaRIIB.

Human T cells that have been conditioned by the proteolytic activity of the major dust mite allergen Der p 1 trigger enhanced immunoglobulin E synthesis by B cells.

BACKGROUND: We have previously demonstrated that the proteolytic activity of Der p 1 selectively cleaves human CD25, the 55 kDa alpha subunit of the IL-2 receptor. As a result of cleavage of surface CD25, peripheral blood T cells produce less IFN-gamma and more IL-4, thereby leading to progressive polarization of the T cells towards a Th2 cytokine profile. Therefore, these observations underline the potential role of the proteolytic activity of Der p 1 in creating a microenvironment conducive for IgE synthesis. OBJECTIVE: To study the effect of T cells that have been conditioned by the proteolytic activity of Der p 1 on IgE synthesis by B cells. METHODS: We have examined this concept in experiments whereby T cells that have been exposed to either proteolytically active or inactive Der p 1 were cocultured with autologous B cells and IgE antibody synthesis was monitored. RESULTS: Here we demonstrate for the first time that coculturing T cells that have been in contact with proteolytically active Der p 1 with autologous B cells leads to augmentation of IgE antibody responses. CONCLUSIONS: The proteolytic activity of Der p 1 conditions human T cells, which then become empowered to trigger enhanced IgE synthesis by B cells.

The proteolytic activity of the major dust mite allergen Der p 1 enhances the IgE antibody response to a bystander antigen.

BACKGROUND: We have recently demonstrated that immunization of mice with proteolytically active Der p 1, the major dust mite allergen, results in a significant enhancement in total and Der p 1-specific IgE synthesis compared to mice immunized with Der p 1 that has been irreversibly blocked with the cysteine protease inhibitors E-64 and iodoacetamide. Thus, the demonstration that the proteolytic activity of Der p 1 enhances total IgE production, apart from increasing Der p 1-specific IgE, suggests that this allergen may have an IgE-specific adjuvant effect. OBJECTIVE: To determine if the proteolytic activity of Der p 1 has an IgE-specific adjuvant effect. METHODS: We have examined this concept in experiments whereby ovalbumin, used as a bystander antigen, was injected alone or coinjected with either proteolytically active or inactive Der p 1 into groups of mice and IgE and IgG antibody responses were measured. RESULTS: Here we demonstrate for the first time that the proteolytic activity of Der p 1, when given at 10-fold higher concentration, enhances the IgE antibody response to ovalbumin. CONCLUSIONS: These findings show that the proteolytic activity of Der p 1 leads to the augmentation of IgE antibody responses to itself and to other allergens present in the microenvironment.

The molecular basis of allergenicity: comparative analysis of the three dimensional structures of diverse allergens reveals a common structural motif.

BACKGROUND: Although a large number of allergens have been characterised, the structural, functional, and biochemical features that these molecules have in common, and that could explain their ability to elicit powerful IgE antibody responses, are still uncertain. Recently, there has been considerable interest in the role of the cysteine protease activity of the house dust mite allergen Der p 1 in biasing the immune response in favour of IgE production. AIMS: To search for remote homologues of Der p 1 with sequences similar to the 30 conserved amino acids surrounding the catalytic cysteine residue (Cys34). METHODS: Potential homologues were analysed by examining their three dimensional structures and multiple sequence alignments using the programs PROPSEARCH, ClustalW, GeneDoc, and Swiss Pdb Viewer. RESULTS: Diverse allergens (for example, the plant cysteine protease papain, the transport protein lipocalin Mus m 1, and the ragweed allergen Amb a 5) have a similar structural motif; namely, a groove resembling the substrate binding groove of Der p 1. The groove is located inside an alpha-beta motif, between an alpha helix on one side and an antiparallel beta sheet on the other side. A similar common motif (a cysteine stabilised alpha-beta fold) can also be found in some toxins and defensins. CONCLUSION: Allergens of diverse sources have a common structural motif, namely a groove located inside an alpha-beta motif, which could potentially serve as a ligand binding site.

Human T cell subset commitment determined by the intrinsic property of antigen: the proteolytic activity of the major mite allergen Der p 1 conditions T cells to produce more IL-4 and less IFN-gamma.

The house dust mite Dermatophagoides pteronyssinus allergen Der p 1 elicits IgE antibody responses in a significant proportion of patients suffering from dust mite allergy. We have recently shown that Der p 1 proteolytically cleaves a cell surface molecule involved in the homeostatic control of human IgE synthesis, namely the IL-2 receptor (CD25) on T cells. As a result, these T cells show markedly diminished proliferation and IFN-gamma secretion in response to stimulation by anti-CD3 antibody. However, these observations still leave open the important issue of whether CD25 cleavage, and the consequent suppression of IFN-gamma secretion, leads to enhanced IL-4 secretion, and whether such cytokine changes would be exhibited by both CD4 and CD8 T cells. Here we demonstrate for the first time that the proteolytic activity of Der p 1 biases human CD4 and CD8 T cells towards a type 2 cytokine profile. Our data provide compelling evidence for the role of the proteolytic activity of Der p 1 in creating a microenvironment conducive for IgE synthesis.

Comparative molecular modelling identifies a common putative IgE epitope on cysteine protease allergens of diverse sources.

BACKGROUND: Previous approaches for studying common allergenic epitopes have mainly focused on sequence comparisons, which unfortunately yield little or no information on the shape of the epitope which is the most important determinant of cross-reactivity. OBJECTIVES: The aim of this study was to investigate the structural basis for cross-reactivity between a previously identified immunodominant epitope of the house dust mite allergen Der p 1 (Leu147-Gln160) and the corresponding epitopes on other allergens that are either taxonomically closely related (i.e. cysteine proteases of other mite species) or representing evolutionary conserved structures (i.e. plant, human and parasite cysteine proteases). METHODS: We carried out comparative molecular modelling on a range of cysteine proteases, including those of other mite species (Der f 1 and Eur m 1), human (cathepsins B, K, L, S and O), plants (papain, chymopapain and actinidin) and parasites (cruzain, cathepsin L-like Leishmania protease, Entamoeba ACP1 protease and Schistosoma Q26534, Q11003 and cathepsin L proteases). RESULTS: Our study shows that all the cysteine proteases investigated here display an epitope corresponding to that previously identified on Der p 1, but with varying shapes and degree of accessibility. It appears that the core of the epitope on these homologous cysteine proteases consists of a centrally located conserved Tyr residue flanked on either sides by accessible amino acids. CONCLUSION: Therefore, these cysteine proteases seem to use similar accessible structures, which may form the basis for the rational design of generic epitope-directed treatment strategies for controlling allergic diseases.

Characterisation of a mouse monoclonal anti-idiotype reactive with a V region sequence commonly used by human immunoglobulins.

BACKGROUND: A mouse monoclonal antibody (2C7/IgG2b kappa) has been described recently, which is directed against the major house dust mite allergen Der p 1, and whose epitope specificity is representative of a major component of the human IgE anti-Der p 1 response. AIMS: To characterise an anti-idiotypic antibody (2G10/IgG1 kappa) raised against monoclonal antibody 2C7 as surrogate human IgE anti-Der p 1. METHODS: The specificity of the anti-idiotype antibody 2G10 was determined by competitive inhibition experiments using human and mouse immunoglobulins of known VH gene families. The epitope recognised by monoclonal antibody 2G10 was located on the molecular model of the Fv (fragment variable) region of monoclonal antibody 2C7. RESULTS: The data suggest that monoclonal antibody 2G10 is directed against a crossreactive idiotype on human IgE that is shared by polyclonal IgG. Competitive inhibition studies against human immunoglobulins, representative of VH2, VH3, and VH4 gene families, showed that monoclonal antibody 2G10 is mostly likely to be directed against sequences encoded by either VH3 or VH4 genes. The fact that monoclonal antibody 2G10 binds to the humanized (complementarity determining region (CDR) grafted) CAMPATH-1H antibody, but not to the original rat CAMPATH-1 YTH34.5.6 antibody, indicates that it is directed against a framework region rather than the CDRs. Analysis of amino acids in the VH region for charge, hydrophobicity, and accessibility suggests that reactivity with monoclonal antibody 2G10 is defined by a hexapeptide spanning residues 74-79 within framework region 3. CONCLUSION: The anti-idiotype monoclonal antibody 2G10 could potentially be used as a probe for determining the contribution of the VH3 and VH4 gene segments to antigenic specificity.

Identification of peptide motifs recognized by a human IgG autoanti-IgE antibody using a phage display library.

BACKGROUND: The potential of murine monoclonal anti-IgE antibodies as long-term therapy for atopic diseases will have to rely, for the time being, on passive antibody administration. There is therefore considerable interest in developing a peptide-based vaccine for active immunization to elicit long-term protective anti-IgE antibodies in the patient. It has been shown that some human IgG autoanti-IgE antibodies have the ability to partially block the binding of IgE to Fc receptors such as Fc epsilonRI. Therefore, the epitopes recognized by such antibodies could have vaccine potential. OBJECTIVE: To determine the epitope specificity of one such human IgG anti-IgE antibody. METHODS: A 15-mer phage-peptide library was used to establish the epitope specificity of an IgG anti-IgE antibody isolated from the serum of an asthma patient. RESULTS: The SRPSP sequence, or part of it (i.e. RPS, RPSP, SPS or PSP), was present in all 18 phage-peptides that have been sequenced. This common motif was found to be within the human epsilon chain sequence Ser341-Thr355 near the N-terminus of the C epsilon3 domain. According to the human Fc epsilon model, the most accessible residues in this sequence are Arg342, Ile350, Arg351, Lys352 and Ser353. CONCLUSIONS: The present data should provide the molecular basis for the rational design of a suitable peptide immunogen (vaccine) for boosting the production of protective autoanti-IgE antibodies.

Prediction of the interacting surfaces in a trimolecular complex formed between the major dust mite allergen Der p 1, a mouse monoclonal anti-Der p 1 antibody, and its anti-idiotype.

BACKGROUND: Two mouse monoclonal antibodies (mAbs) have been described recently; namely, mAb 2C7 (IgG2b kappa), which is directed against the major house dust mite allergen Der p 1, and mAb 2G10 (IgG1 kappa), which is an anti-idiotypic antibody raised against mAb 2C7. The anti-idiotype mAb 2G10 does not block the binding of mAb 2C7 to Der p 1, which means that mAb 2C7 can simultaneously bind to Der p 1 and to mAb 2G10, thereby generating a trimolecular complex consisting of antigen-idiotype-anti-idiotype. AIMS: To sequence and model the V region of the anti-idiotypic antibody mAb 2G10 to enable the prediction of the interacting surfaces in the trimolecular complex consisting of Der p 1-mAb 2C7-mAb 2G10. METHODS: DNA sequencing of mAb 2G10 was carried out and the Swiss Model and Swiss PDB-Viewer programs were used to build a three dimensional model of the trimolecular complex. RESULTS: Complementarity of shape and charge was revealed when comparing the protrusion of the previously determined Der p 1 epitope (Leu147-Gln160) with the cavity formed by the complementarity determining regions (CDRs) of mAb 2C7. Such complementarity was also observed between the mAb 2C7 epitope predicted to be recognised by mAb 2G10 (residues Lys19 from framework region 1 (FRW1) and Ser74-Gln81 from FRW3) and residues from the CDRs of mAb 2G10 (a negatively charged patch flanked by the residues Asp55H/Glu58H and Glu27L/Glu27cL). As expected, the location of the mAb 2C7 epitope recognised by mAb 2G10 does not appear to interfere with the binding of Der p 1 to mAb 2C7. CONCLUSION: Although the results obtained represent only an approximation, they nevertheless provide a rare insight into how an antigen (Der p 1) might bind to its antibody (mAb 2C7) while in complex with an anti-idiotype (mAb 2G10).

The cysteine protease activity of the major dust mite allergen Der p 1 selectively enhances the immunoglobulin E antibody response.

The house dust mite Dermatophagoides pteronyssinus allergen Der p 1 is the most immunodominant allergen involved in the expression of dust mite-specific immunoglobulin (Ig)E-mediated hypersensitivity. The reason for this potent IgE-eliciting property of Der p 1 remains unknown, but there is mounting in vitro evidence linking the allergenicity of Der p 1 to its cysteine protease activity. Here we demonstrate for the first time that immunization of mice with proteolytically active Der p 1 results in a significant enhancement in total IgE and Der p 1-specific IgE synthesis compared with animals immunized with Der p 1 that was irreversibly blocked with the cysteine protease inhibitor E-64. We conclude that the proteolytic activity of Der p 1 is a major contributor to its allergenicity.

The use of phage-peptide libraries to define the epitope specificity of a mouse monoclonal anti-Der p 1 antibody representative of a major component of the human immunoglobulin E anti-Der p 1 response.

BACKGROUND: More than 80% of individuals who are sensitive to the dust mite Dermatophagoides pteronyssinus produce immunoglobulin (Ig) E antibodies to Der p 1, the most significant domestic allergen. There is therefore considerable interest in elucidating the interaction between human IgE and Der p 1, as a basis for developing strategies for therapeutic intervention. OBJECTIVES: We have therefore sought to determine the Der p 1 epitope recognized by a mouse monoclonal anti-Der p 1 antibody (mAb 2C7) representative of a major component of the human IgE anti-Der p 1 response. METHODS: M13 15mer and T7 9mer bacteriophage-peptide display libraries were screened with mAb 2C7. Mimotope sequences were defined and compared with the native Der p 1 sequence and with those of three homologous molecules, namely chymopapain, papain and actinidin. The sequence of a candidate epitope was then located in the three-dimensional model of Der p 1 and the corresponding sequences in the homologous molecules were studied for accessibility in the three-dimensional structure. RESULTS: We have demonstrated that it is possible to isolate phage clones with peptide inserts specific for mAb 2C7. Examination of the sequences obtained and the location of the corresponding epitope within the three-dimensional model of Der p 1 has shown that mAb 2C7 recognizes a conformational epitope comprising the sequence Leu147-Gln160. The relevance of the identified epitope was established by showing that native Der p 1 can block the binding of specific phage clones to mAb 2C7. Similar sequences were identified within the three-dimensional structures of chymopapain, papain and actinidin, thereby providing a structure-based explanation for immunological cross-reactivity. CONCLUSION: The identification of the Der p 1 sequence Leu147-Gln160 as a potential epitope recognized by a major component of the human IgE anti-Der p 1 response may provide therapeutic opportunities for disrupting the interaction between IgE and this important allergen.