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OIT correlates with increased allergen-binding B cells in patients with peanut allergies

Peanut allergen-specific B cells in patients express mutated antibody genes and bind to linear and conformational epitopes, according to study results.

Also, oral immunotherapy is linked to increased frequencies of allergen-binding B cells in the blood members of an allergen-specific clone.

Ramona A. Hoh, PhD, from the department of pathology at Stanford University, and colleagues conducted a phase 1 study and collected blood samples from 27 patients aged 4 to 43 years with double blind, placebo-controlled food challenge-confirmed peanut allergy undergoing peanut oral immunotherapy (OIT).

The researchers wanted to see if they could characterize peanut allergen-specific B-cell populations and the sequences and binding activities of their antibodies before and during immunotherapy.

The researchers collected samples from 14 patients at baseline alone, nine patients during OIT alone and four patients at baseline and during OIT.

The results indicated median allergen-binding B-cell frequencies as 0.0097% (Ara h 1) and 0.029% (Ara h 2) of B cells in baseline blood from allergic patients and approximately threefold higher during immunotherapy.

Five of 57 allergen-specific cells also belonged to clones containing immunoglobulin-E-expressing members.

The researchers noted a significant proportion of allergen-specific antibodies as being mutated and they detected binding to conformational and linear allergen epitopes.

“These findings represent an initial evaluation of the antibodies expressed by peanut allergen-specific B cells in human subjects,” the researchers wrote. “Extension of these findings to large numbers of patients and correlative analysis with other immune system features, such as T-cell responses and mast cell and basophil functional status, both before treatment and during OIT should provide additional details and result in an integrated understanding of allergic phenotypes and therapeutic responses in the coming years.” – by Ryan McDonald

Disclosure: Hoh reports receiving research support from the Child Health Research Institute of Stanford. Please see the full study for a list of all other authors’ relevant financial disclosures.