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Epitope specificity determines cross-protection of a SIT-induced IgG4 antibody

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Gadermaier, E. and James, L.K. and Shamji, M.H. and Blatt, K. and Fauland, K. and Zieglmayer, P. and Garmatiuk, T. and Focke-Tejkl, M. and Villalba Díaz, Mayte and Beavil, R. and Keller, W. and Valent, P. and Durham, S.R. and Gould, H.J. and Flicker, S. and Valenta, R. (2015) Epitope specificity determines cross-protection of a SIT-induced IgG4 antibody. Allergy . ISSN 1398-9995 (On line) (Submitted)

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Official URL: http://onlinelibrary.wiley.com/doi/10.1111/all.12710/abstract



Abstract

The calcium-binding 2EF-hand protein Phl p 7 from timothy grass pollen is a highly cross-reactive pollen pan-allergen that can induce severe clinical symptoms in allergic patients. Recently, a human monoclonal Phl p 7-specific IgG4 antibody (mAb102.1F10) was isolated from a patient who had received grass pollen-specific immunotherapy (SIT).We studied epitope specificity, cross-reactivity, affinity and cross-protection of mAb102.1F10 towards homologous calcium-binding pollen allergens. Sequence comparisons and molecular modelling studies were performed with ClustalW and SPADE, respectively. Surface plasmon resonance measurements were done with purified recombinant allergens. Binding and cross-reactivity of patients’ IgE and mAb102.1F10 to calcium-binding allergens and peptides thereof was studied with quantitative RAST-based methods, in ELISA, basophil activation and IgE-facilitated allergen presentation experiments. Allergens from Timothy grass (Phl p 7), Alder (Aln g 4), Birch (Bet v 4), Turnip rape (Bra r 1), Lamb′s quarter (Che a 3) and Olive (Ole e 3, Ole e 8) showed high sequence similarity and cross-reacted with allergic patients’ IgE. mAb102.1F10 bound the C-terminal portion of Phl p 7 in a calcium-dependent manner. It cross-reacted with high affinity with Ole e 3 whereas binding and affinity to the other allergens was low. mAb102.1F10 showed limited inhibition of patients’ IgE binding and basophil activation. Sequence comparison and surface exposure calculations identified three amino acids likely to be responsible for limited cross-reactivity.Our results demonstrate that a small number of amino acid differences among cross-reactive allergens can reduce the affinity of binding by a SIT-induced IgG and thus limit cross-protection.


Item Type:Article
Uncontrolled Keywords:calcium-binding protein;cross-reactivity;pollen allergen;recombinant allergen;SIT-induced IgG antibody
Subjects:Medical sciences > Medicine > Allergy
Medical sciences > Medicine > Biochemistry
ID Code:33180
Deposited On:08 Oct 2015 13:33
Last Modified:09 Oct 2015 08:52

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