Mutational analysis of major, sequential IgE-binding epitopes in αs1-casein, a major cow's milk allergen

Cocco, Renata Rodrigues; Järvinen, Kirsi-Marjut; Sampson, Hugh A.; Beyer, Kirsten

doi:10.1067/mai.2003.1617

Cited by 84 publications

(74 citation statements)

References 21 publications

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“…Lysines have already been shown to be critical for IgE binding in linear epitope analyses of the related grass pollen allergen Lol p 5 [17] and other allergens [13, 14, 16] or at least present in IgE-binding regions [1, 12]. But since IgE epitopes are known to be mainly conformational, it was essential to measure the influence of missing lysines using an allergen with intact 3-dimensional structure.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, IgE antibodies bind to their epitopes with higher affinities than IgG antibodies, the latter often directed against linear epitopes [11, 12]. From what we have learned from epitope mappings with linear peptides, it is important to note that IgE epitopes are primarily composed of charged and hydrophobic amino acids, and many of them contain at least one lysine [2,13,14,15,16]. Interestingly, the two dominant IgE epitopes on a group V grass pollen allergen completely lost their IgE-binding ability when the lysines were exchanged by nonpolar amino acids [2, 17].…”

Section: Introductionmentioning

confidence: 99%

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Lysine as a Critical Amino Acid for IgE Binding in Phl p 5b C Terminus

Gehlhar

Rajashankar²,

Hofmann³

et al. 2006

Int Arch Allergy Immunol

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Background: Allergens induce the formation of specific immunoglobulin (Ig)E and harbor at least two IgE-binding regions (epitopes) to facilitate crosslinking of basophilic or mast-cell-bound specific IgE antibodies. Studies mapping linear epitopes have shown that these regions often contain charged or hydrophobic amino acids. Nevertheless, these studies are hampered by limited significance due to the often conformational nature of IgE epitopes. This prompted us to study the role of lysines in the context of an intact 3-dimensional model. Methods: Major allergen Phl p 5b from timothy grass bears 12 lysines in its C-terminal half. Using site-directed mutagenesis, we substituted all 10 surface-exposed lysines by alanines. Results: Although structural integrity of the lysine-deficient mutant was not altered, IgE-binding capacity measured by ELISA inhibition tests and crosslinking activity in ex vivo basophil stimulation and in vivo skin prick tests were significantly diminished. Interestingly, binding of specific IgG antibodies was considerably less reduced by loss of lysines. Conclusion: Lysine is an important amino acid for IgE binding in more than one epitope of major grass pollen allergen Phl p 5b C terminus. Allergenicity, but not IgG binding of the molecule, is substantially diminished by single amino acid substitutions without structural integrity being hampered.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lysine as a Critical Amino Acid for IgE Binding in Phl p 5b C Terminus

Gehlhar

Rajashankar²,

Hofmann³

et al. 2006

Int Arch Allergy Immunol

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“…The sequence of events and biomarkers that define individuals with persistent food allergy and those who outgrow their food allergy remain unclear. Sequential rather than conformational epitopes as well as greater diversity, higher affinity, and different sensitization patterns is associated with persistent allergy and different severity of the allergic reaction (106)(107)(108)(109)(110)(111), suggesting an important role for Bcell antigen presentation and T-cell help in the maintenance of food sensitization (112). In addition, the subgroup that develops tolerance displays lower levels of allergen-specific IgE and SPT.…”

Section: Oral and Sublingual Immunotherapy In Food Allergymentioning

confidence: 99%

Markers of tolerance development to food allergens

Ponce

Diesner

Szépfalusi

et al. 2016

Allergy

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IgE-mediated reactions to food allergens are the most common cause of anaphylaxis in childhood. Although allergies to cow's milk, egg, or soy proteins, in contrast to peanut and tree nut allergens, resolve within the first 6 years of life in up to 60% due to natural tolerance development, this process is not well understood. At present, there is no cure or treatment for food allergy that would result in an induction of tolerance to the symptom-eliciting food. Avoidance, providing an emergency plan and education, is the standard of treatment. Oral immunotherapeutic approaches have been proven reasonable efficacy; however, they are associated with high rates of side-effects and low numbers of patients achieving tolerance. Nevertheless, mechanisms that take place during oral immunotherapy may help to understand tolerance development. On the basis of these therapeutic interventions, events like loss of basophil activation and induction of regulatory lymphocyte subsets and of blocking antibodies have been described. Their functional importance at a clinical level, however, remains to be investigated in detail. Consequently, there is eminent need to understand the process of tolerance development to food allergens and define biomarkers to develop and monitor new treatment strategies for food allergy.IgE-mediated food allergy represents the most important cause of anaphylaxis in childhood. While milk and egg allergy are associated with a high rate of natural tolerance development within the first 6 years of life, this is less clear for other food allergies. Consequently, once it is communicated the diagnosis persists often lifelong severely impacting the quality of life of the patient and the environment despite the recommendation to reconsider clinical tolerance development from time to time.Currently, avoidance, providing an emergency plan and teaching, is the standard of treatment; however, there is no cure or treatment that has reached the level of recommendation to re-induce tolerance to the symptom-eliciting food. Tolerance assessment occurs either via oral food challenges or due to unintended exposure. Given the cost and time intensiveness of oral food challenges and its potential harmfulness, there is eminent need to understand the process of tolerance development and define markers thereof to develop and monitor new treatment strategies for food allergy. This review aimed to provide an overview on recent advances regarding markers and mechanisms of tolerance development to food allergens.Oral tolerance in the context of food allergy is considered to occur if the antigen/food can be ingested without problems despite prolonged periods of avoidance, while the status of desensitization is strictly dependent on regular ingestion of the respective food in order to confer protection from allergic reactions. Currently, there is no general consensus on the exact time frame of avoidance and re-exposure that would allow the usage of the terminus tolerance that is considered equivalent to cure in the context of or...

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“…Ab binding sites are thought to be dependent on the native conformation of the allergen, and epitope identification using short overlapping peptides has been criticized in that this strategy does not produce meaningful results. However, this strategy has been used to identify major epitopes of peanut allergens (37)(38)(39), and studies of milk and peanut allergens suggested (40,41) associations between IgE Ab reactivities to linear peptides and severity of disease.…”

Section: Figurementioning

confidence: 99%

Reduced Allergenic Potency of VR9-1, a Mutant of the Major Shrimp Allergen Pen a 1 (Tropomyosin)

Reese

Viebranz

Leong-Kee

et al. 2005

The Journal of Immunology

106

101

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The major shrimp allergen, tropomyosin, is an excellent model allergen for studying the influence of mutations within the primary structure on the allergenic potency of an allergen; Pen a 1 allows systematic evaluation and comparison of Ab-binding epitopes, because amino acid sequences of both allergenic and nonallergenic tropomyosins are known. Individually recognized IgE Ab-binding epitopes, amino acid positions, and substitutions critical for IgE Ab binding were identified by combinatorial substitution analysis, and 12 positions deemed critical were mutated in the eight major epitopes. The mutant VR9-1 was characterized with regard to allergenic potency by mediator release assays using sera from shrimp-allergic subjects and sera from BALB/c, C57BL/6J, C3H/HeJ, and CBA/J mice sensitized with shrimp extract using alum, cholera toxin, and Bordetella pertussis, as adjuvants. The secondary structure of VR9-1 was not altered; however, the allergenic potency was reduced by 90–98% measuring allergen-specific mediator release from humanized rat basophilic leukemia (RBL) cells, RBL 30/25. Reduced mediator release of RBL-2H3 cells sensitized with sera from mice that were immunized with shrimp extract indicated that mice produced IgE Abs to Pen a 1 and to the same epitopes as humans did. In conclusion, data obtained by mapping sequential epitopes were used to generate a Pen a 1 mutant with significantly reduced allergenic potency. Epitopes that are relevant for human IgE Ab binding are also major binding sites for murine IgE Abs. These results indicate that the murine model might be used to optimize the Pen a 1 mutant for future therapeutic use.

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Mutational analysis of major, sequential IgE-binding epitopes in αs1-casein, a major cow's milk allergen

Cited by 84 publications

References 21 publications

Lysine as a Critical Amino Acid for IgE Binding in Phl p 5b C Terminus

Lysine as a Critical Amino Acid for IgE Binding in Phl p 5b C Terminus

Markers of tolerance development to food allergens

Reduced Allergenic Potency of VR9-1, a Mutant of the Major Shrimp Allergen Pen a 1 (Tropomyosin)

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