D3.04 - Sensitization Pattern and Characteristics of IgE Repertoire in Allergic Children with Excessively High Serum IgE Levels

Immunoglobin E (IgE) is closely related to allergic symptoms. Patients with common allergic diseases, including atopic dermatitis (AD), asthma and allergic rhinitis, often present with excessively high serum IgE levels, yet the sensitization pattern could vary largely. In this study, the aim is to analyze the characteristics of IgE-producing B cell repertoire in allergic children with high serum IgE levels.

Pediatric patients presented with allergic diseases with serum IgE > 1000 IU/mL were enrolled, and divided into two groups according to their sensitization patterns to common allergens (poly-sensitized and pauci-sensitized). Medical historie were taken and labratory data were reviewed. Lymphocytes were isolated from their blood samples for RNA extraction. Library construction was done using primer sets from iRepertoire IgH repertoire kits (iRepertoire Inc., Huntsville, AL, USA). Sequencing of B cell receptor (BCR) transcripts was done using MiSeq (Illumina, San Diego, CA, USA). Basic statistics were processed via the iRepertoire pipeline and repertoire characteristics were analyzed using Excel and STATA. Phylogenetic study of IGHE CDR3 reads was done using R scripts.

From July, 2024 to December, 2025, samples from 40 patients had been obtained. Clinically, patients with asthma and/or allergic rhinitis (n =11) were mostly pauci-sensitized, while patients with AD (n=29) could be either poly- or pauci-sensitized. Ten of the samples had been completed of RNA sequencing and statistical analysis, including 2 pauci-sensitized and 8 poly-sensitized patients. The pauci-sensitized patients had higher proportion of IGHE reads (mean: 5.81%) within the whole repertoire than the poly-sensitized patients (mean: 2.26%) despite the more restricted clone numbers. However, the difference was less significant regarding the proportion of unique CDR3 reads. Three diversity indices (D50, Shannon Entropy and Diversity Index (DI)) were applied to evaluate the constitution of IGHE-expressing B cells. The pauci-sensitized group had lower D50 and DI compared to the poly-sensitized group. Some of the poly-sensitized patients had unexpectedly low IgE diversity, implying that few IgE clones could be responsible for an extensive sensitization pattern. As for phylogenetic analysis, current samples showed that IGHG4 reads are phylogenetically closest to IGHE reads in CDR3 sequences in all isotypes, implying an important role of IgG₄ in the sequential class-switching to pathogenic IgE.

To briefly summarize, pauci-sensitized patients had higher proportion of IGHE reads and lower diversity score compared to poly-sensitized patients.