Distinction between peanut allergy and tolerance by characterization of B-cell receptor repertoires

Background: Specific IgE against a peanut 2S albumin (Ara h2 or 6) is the best predictor of clinically relevant peanut sensitization. However, sIgE levels of peanut allergic and those of peanut sensitized but tolerant patients partly overlap, highlighting the need for improved diagnostics to prevent incorrect diagnosis and consequently unnecessary food restrictions. Thus, we sought to explore differences in V(D)J gene transcripts coding for peanut 2S albumin-specific monoclonal antibodies (mAbs) from allergic and sensitized but tolerant donors Methods 2S albumin-binding B-cells were single-cell sorted from peripheral blood of peanut allergic (n=6) and tolerant (n=6) donors sensitized to Ara h2 and/or 6 (≥ 0.1 kU/l) and non-atopic controls (n=5). Corresponding heavy and light chain gene transcripts were heterologously expressed as mAbs and tested for specificity to native Ara h2 and 6. HCDR3 sequence motifs were identified by Levenshtein distances and hierarchically clustering. Results The frequency of 2S albumin-binding B-cells was increased in allergic (median: 0.01%) compared to tolerant (median: 0.006%) and non-atopic donors (median: 0.0015%, p=0.008). The majority of mAbs (74%, 29/39) bound specifically to Ara h2 and/or 6. Non-specific mAbs (9/10) were mainly derived from non-atopic controls. In allergic donors, 89% of heavy chain gene transcripts consisted of VH3-family genes, compared with only 54% in sensitized but tolerant and 63% of non-atopic donors. Additionally, certain HCDR3 sequence motifs were associated with allergy or tolerance upon hierarchical clustering of their Levenshtein distances. Conclusions HCDR3 sequence motifs associated with allergy or tolerance may support correct diagnosis of patients with suspected peanut allergy.