Background Peanut oral immunotherapy (PNOIT) induces persistent tolerance to peanut in a subset of patients and induces specific antibodies that might play a role in clinical protection. However, the contribution of induced antibody clones to clinical tolerance in PNOIT is unknown. Objective We hypothesized that PNOIT induces a clonal, allergen-specific B-cell response that could serve as a surrogate for clinical outcomes. Methods We used a fluorescent Ara h 2 multimer for affinity selection of Ara h 2-specific B cells and subsequent single-cell immunoglobulin amplification. The diversity of related clones was evaluated by means of next-generation sequencing of immunoglobulin heavy chains from circulating memory B cells with 2x250 paired-end sequencing on the Illumina MiSeq platform. Results Expression of class-switched antibodies from Ara h 2-positive cells confirms enrichment for Ara h 2 specificity. PNOIT induces an early and transient expansion of circulating Ara h 2-specific memory B cells that peaks at week 7. Ara h 2-specific sequences from memory cells have rates of nonsilent mutations consistent with affinity maturation. The repertoire of Ara h 2-specific antibodies is oligoclonal. Next-generation sequencing-based repertoire analysis of circulating memory B cells reveals evidence for convergent selection of related sequences in 3 unrelated subjects, suggesting the presence of similar Ara h 2-specific B-cell clones. Conclusions Using a novel affinity selection approach to identify antigen-specific B cells, we demonstrate that the early PNOIT-induced Ara h 2-specific B-cell receptor repertoire is oligoclonal and somatically hypermutated and shares similar clonal groups among unrelated subjects consistent with convergent selection.
Patil, S. U., Ogunniyi, A. O., Calatroni, A., Tadigotla, V. R., Ruiter, B., Ma, A., … Shreffler, W. G. (2015). Peanut oral immunotherapy transiently expands circulating Ara h 2-specific B cells with a homologous repertoire in unrelated subjects. Journal of Allergy and Clinical Immunology, 136(1), 125-134.e12. https://doi.org/10.1016/j.jaci.2015.03.026