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J Allergy Clin Immunol. 2012 Sep;130(3):663-670.e3. doi: 10.1016/j.jaci.2012.04.006. Epub 2012 May 13.

Allergen specificity of IgG(4)-expressing B cells in patients with grass pollen allergy undergoing immunotherapy.

Author information

1
Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom. louisa.james@kcl.ac.uk

Abstract

BACKGROUND:

Serum IgG(4) responses to allergen immunotherapy are well documented as blocking allergen binding to receptor-bound IgE on antigen-presenting cells and effector cells, but the molecular characteristics of treatment-induced IgG(4), particularly in relation to expressed antibody, are poorly defined.

OBJECTIVES:

We aimed to clone and express recombinant IgG(4) from patients receiving grass pollen immunotherapy using single B cells to obtain matched heavy- and light-chain pairs.

METHODS:

IgG(4)(+) B cells were enriched from blood samples taken from 5 patients receiving grass pollen immunotherapy. Matched heavy- and light-chain variable-region sequences were amplified from single IgG(4)(+) B cells. Variable regions were cloned and expressed as recombinant IgG(4). Binding analysis of grass pollen-specific IgG(4) was performed by using surface plasmon resonance. Functional assays were used to determine IgE blocking activity. In a separate experiment grass pollen-specific antibodies were depleted from serum samples to determine the proportion of grass pollen-specific IgG(4) within total IgG(4).

RESULTS:

Depletion of grass pollen-specific antibodies from serum led to a modest reduction in total IgG(4) levels. Matched heavy- and light-chain sequences were cloned from single IgG(4)(+) B cells and expressed as recombinant IgG(4). We identified an IgG(4) that binds with extremely high affinity to the grass pollen allergen Phl p 7. Furthermore, we found that a single specific mAb can block IgE-mediated facilitated allergen presentation, as well as IgE-mediated basophil activation.

CONCLUSION:

Although increases in IgG(4) levels cannot be wholly accounted for within the allergen-specific fraction, allergen immunotherapy might result in the production of high-affinity allergen-specific blocking IgG(4).

PMID:
22583928
DOI:
10.1016/j.jaci.2012.04.006
[Indexed for MEDLINE]

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