Clonal evolution and stereotyped sequences of human IgE lineages in aeroallergen-specific immunotherapy

Prospective Piperacillin Lymphocyte Transformation Testing in Patients With Cystic Fibrosis Receiving Regular and Desensitization Courses of Piperacillin-Tazobactam

BACKGROUND

Piperacillin-tazobactam is used in patients with cystic fibrosis to treat recurrent respiratory infections. Exposure is associated with a high frequency of nonimmediate hypersensitivity.

OBJECTIVE

To assess the applicability of the lymphocyte transformation test (LTT) for the diagnosis of piperacillin hypersensitivity and the influence of desensitization on piperacillin-specific T-cell responses.

METHODS

Study arm 1 was an analysis of LTT responses from 58 naive/baseline tolerant patients with samples collected over a 3-year interventional phase. In study arm 2, 17 hypersensitive patients were recruited and LTTs were conducted before and after desensitization. Clinical hypersensitivity reactions in both arms were monitored over an 8-year observational period.

RESULTS

In study arm 1, 58 patients received 611 piperacillin-tazobactam courses (range, 2-40; mean ± SD, 10.5 ± 8.1) during the interventional phase; 11 patients developed hypersensitivity. The patients who remained tolerant received 236 piperacillin-tazobactam courses in the observational period, 9 of whom developed hypersensitivity. Ten of 11 interventional phase hypersensitive patients had a positive LTT whereas one remained negative. We recorded 136 negative LTTs with 39 tolerant patients, whereas eight patients had a positive LTT and four developed hypersensitivity during the observational period. Ten LTT-positive patients in study arm 2 underwent piperacillin-tazobactam desensitization, with seven tolerating the drug. The strength of the LTT decreased during desensitization, and negative results were recorded for a minimum of 14 days. During follow-up, eight patients tolerated 62 piperacillin-tazobactam courses through desensitization.

CONCLUSIONS

The LTT is a sensitive marker of drug sensitization that could be used to inform future patient management. Desensitization is associated with attenuation of the piperacillin-specific T-cell response.

Omics in allergy and asthma

This review explores the transformative impact of omics technologies on allergy and asthma research in recent years, focusing on advancements in high-throughput technologies related to genomics and transcriptomics. In particular, the rapid spread of single-cell RNA sequencing has markedly advanced our understanding of the molecular pathology of allergic diseases. Furthermore, high-throughput genome sequencing has accelerated the discovery of monogenic disorders that were previously overlooked as ordinary intractable allergic diseases. We also introduce microbiomics, proteomics, lipidomics, and metabolomics, which are quickly growing areas of research interest, although many of their current findings remain inconclusive as solid evidence. By integrating these omics data, we will gain deeper insights into disease mechanisms, leading to the development of precision medicine approaches that promise to enhance treatment outcomes.

B cell memory of Immunoglobulin E (IgE) antibody responses in allergy

Immunoglobulin E (IgE)-mediated allergic diseases are driven by high-affinity allergen-specific IgE antibodies. IgE antibodies bind to Fc epsilon receptors on mast cells, prompting their degranulation and initiating inflammatory reactions upon allergen crosslinking. While most IgE-producing plasma cells have short lifespans, and IgE memory B cells are exceedingly rare, studies have indicated that non-IgE-expressing type 2-polarized IgG memory B cells serve as a reservoir of IgE memory in allergies. This review explores the B cell populations underlying IgE-mediated allergies, including the cellular and molecular processes that drive IgE class switching from non-IgE memory B cells. It highlights emerging evidence from human studies identifying type 2 IgG memory B cells as the source of pathogenic IgE in allergic responses.

Linear epitopes of bony fish β-parvalbumins

Introduction

Fish β-parvalbumins are common targets of allergy-causing immunity. The nature of antibody responses to such allergens determines the biological outcome following exposure to fish. Specific epitopes on these allergens recognised by antibodies are incompletely characterised.

Methods

High-content peptide microarrays offer a solution to the identification of linear epitopes recognised by antibodies. We characterized IgG and IgG4 recognition of linear epitopes of fish β-parvalbumins defined in the WHO/IUIS allergen database as such responses hold the potential to counter an allergic reaction to these allergens. Peripheral blood samples, collected over three years, of 15 atopic but not fish-allergic subjects were investigated using a microarray platform that carried every possible 16-mer peptide of known isoforms and isoallergens of these and other allergens.

Results

Interindividual differences in epitope recognition patterns were observed. In contrast, reactivity patterns in a given individual were by comparison more stable during the 3 years-course of the study. Nevertheless, evidence of the induction of novel specificities over time was identified across multiple regions of the allergens. Particularly reactive epitopes were identified in the D helix of Cyp c 1 and in the C-terminus of Gad c 1 and Gad m 1.02. Residues important for the recognition of certain linear epitopes were identified. Patterns of differential recognition of isoallergens were observed in some subjects.

Conclusions

Altogether, comprehensive analysis of antibody recognition of linear epitopes of multiple allergens enables characterisation of the nature of the antibody responses targeting this important set of food allergens.