Poster Tour: Thursday

Introduction and Aim: TCR-T cell therapies targeting NY-ESO-1, typically using avidity-enhanced TCRs, show clinical efficacy but are associated with severe toxicities, potentially driven by excessive TCR avidity and off-target reactivity. We investigated whether naturally occurring NY-ESO-1-specific TCRs provide a safer alternative aiming for prospective clinical trials.

Methods: 30 natural TCRαβ clonotypes identified by scRNA-Seq from melanoma survivors were expressed in the Jurkat CD8^pos TCR^ko T cell subline. Binding avidity was assessed using NY-ESO-1 multimers/tetramers ±CD8 and integrated into an avidity score. Functional avidity (EC₅₀) was tested with NY-ESO-1-loaded T2 cells, while off-target reactivity was evaluated in binding and functional assays with COG7 and MKI67 cross-reactive peptides. A set of avidity-enhanced and clinically-used TCRs were also analyzed in parallel.

Results: Natural TCRs spanned a wide binding avidity range, with strong positive correlation between binding avidity and functional responses. Avidity-enhanced TCRs exhibited generally much higher cross-reactive binding and activation compared to natural clonotypes. In contrast, most natural TCRs of higher binding avidity showed reduced to absent off-target reactivity while maintaining high functional activity.

Conclusions: Natural TCRs display diverse yet controlled avidity profiles with much lower cross-reactivity than the avidity-enhanced clinically-used receptors. These findings support their development as safer, physiologically relevant candidates for next-generation TCR-T therapies.

Idiopathic inflammatory myopathies (IIM) are rare autoimmune muscle diseases characterized by chronic inflammation, fibrosis, and progressive muscle weakness. While adaptive immune responses are well studied, the role of natural killer (NK) cells in muscle injury and regeneration remains unclear. Emerging evidence suggests that NK cells may acquire either pathogenic or reparative functions depending on the inflammatory and metabolic microenvironment. This project investigates how transforming growth factor beta (TGFβ) signaling and lactate accumulation regulate NK cell phenotype and function in IIM muscle tissue.

We will combine translational clinical analyses with mechanistic in vitro studies. NK cells from patients' blood and muscle biopsies will be characterized using flow cytometry, tissue imaging, and transcriptomic approaches. Lactate and TGFβ1 levels will be evaluated as candidate biomarkers associated with disease activity and fibrosis. Functional studies will assess the effects of lactate and TGFβ1/2/3 variants on NK cell function using primary human NK cells and myoblasts.

Preliminary data show that elevated lactate impairs NK cell migration and cytotoxicity while increasing tissue-residency markers such as CD69. TGFβ1 also suppresses NK cell-mediated cytotoxicity against human myoblasts. Together, these findings support the hypothesis that the IIM microenvironment promotes a tissue-retained, less cytotoxic NK cell state.

This study aims to distinguish pathogenic from reparative NK cell programs and may identify novel biomarkers and therapeutic targets for IIM.

Allergic asthma affects over 300 million individuals worldwide and remains a significant clinical burden. Allergen immunotherapy is the only disease-modifying treatment but has limited applicability in severe cases. Here, we investigated the therapeutic potential of regulatory T cells (Tregs) engineered with chimeric allergen receptors (CAlleRs) targeting the major birch pollen allergen Bet v 1. Four anti–Bet v 1 human antibodies were identified and used to generate CAlleR constructs in Tregs. Antigen-specific activation and suppressive function were assessed in vitro. Therapeutic efficacy was evaluated in a murine model of birch pollen–induced allergic airway inflammation. CAlleR Tregs showed allergen-specific activation and suppressive function in vitro. In vivo, adoptive transfer of CAlleR Tregs significantly reduced airway hyperresponsiveness and inflammation. Mechanistically, CAlleR Tregs migrated to the lungs and mediastinal lymph nodes, interacted with CD11c⁺ dendritic cells, and were activated in an Fcγ receptor–dependent manner by cross-presenting Bet v 1 stabilized by non-competitive anti-Bet v 1 antibodies. These findings unveil a novel mechanism for targeting soluble antigens and highlight the potential of CAlleR Tregs as a therapeutic strategy for severe allergic diseases.

Introduction/aim of the study: Perioperative anaphylaxis remains a major diagnostic challenge, particularly when multiple potential triggers are administered in rapid sequence. Although antibiotics and anaesthetic agents are often prioritized in the work-up, chlorhexidine remains an under-recognized cause despite its widespread perioperative use. We aimed to highlight chlorhexidine as a relevant trigger of perioperative anaphylaxis and to illustrate the diagnostic value of basophil activation testing (BAT) in this setting.

Design and methods: Two patients were evaluated in an Immunoallergology department following perioperative anaphylaxis. A detailed review of perioperative exposures was undertaken. The diagnostic investigation included skin testing, measurement of chlorhexidine-specific IgE, and basophil activation testing (BAT).

Results: The first case involved a male patient who developed anaphylaxis shortly after urinary catheterisation with a chlorhexidine-containing lubricant, following an otherwise uneventful general anaesthetic. The second involved a 36-year-old woman with two episodes of perioperative anaphylactic shock. In both cases, anaesthetic drugs were excluded and chlorhexidine sensitisation was confirmed by positive specific IgE, skin prick tests and BAT.

Conclusions: Chlorhexidine should be systematically considered in the evaluation of perioperative anaphylaxis. BAT may be particularly useful in complex cases, increasing diagnostic confidence, helping exclude alternative culprits, and supporting safer planning of future procedures.

Background: Skin prick testing (SPT) is the gold standard for diagnosing IgE-mediated allergies. Traditional manual SPT is subject to operator variability and labour-intensive processes. Digital devices have been developed to standardise wheal measurement and reduce inter-operator variability.

Objective: To assess the sensitivity and specificity of a Digital SPT device (DSPT) versus manual SPT, compare time efficiency, and evaluate technology acceptability.

Methods: A single-centre, cross-sectional study enrolled 225 participants who underwent SPT using both methods with 17 allergens, with positive and negative controls. Primary endpoints were sensitivity and specificity; secondary endpoints were time to result and inter-method agreement.

Results: Of 225 participants (147 females, 78 males; mean age 39 years), the device achieved 87.6% sensitivity, 80.0% specificity, and an area under the curve (AUC) of 0.952 for histamine, with 98.2% specificity for saline. Processing time was comparable (device: 60 s, interquartile range IQR 53–68 s vs manual: 56 s, IQR 40–73 s; p=0.042), with manual time increasing with complexity while device time remained constant. Across five allergens, sensitivity ranged 75.0–92.6% and specificity 94.9–100%, with substantial to near-perfect inter-method agreement (Cohen's kappa [κ]=0.73–0.902).

Conclusion: The DSPT showed high specificity and strong inter-method agreement, supporting standardisation of wheal measurement. Moderate sensitivity requires manual confirmation of negative results, and multicenter validation is needed before clinical adoption.

While "trained immunity" has been extensively studied in infectious diseases and cancer, its mechanisms and functions in chronic inflammatory disorders such as asthma remain poorly characterized. Our previous work identified an inflammatory epigenetic and metabolic memory in macrophages from patients with type 2 (T2)-high asthma. However, how this program is affected by biologics targeting type 2 cytokines is unknown. Here, we aimed to dissect how dupilumab/ anti-IL-4Ralpha treatment affects "training" of monocytes and macrophages in patients and mice with T2-high asthma. In a mouse model of chronic T2-high asthma, we found that anti-IL-4Rα treatment robustly reduces type 2 airway inflammation while leaving Th17 responses unaffected. Multi-omic profiling, including bulk and single-cell RNA-seq, ATAC-seq, and lipidomics, showed that anti-IL-4Rα treatment restores healthy peripheral prostaglandin profiles or monocyte phenotype and function in allergen-challenged mice or asthmatic patients. In contrast, anti-IL-4Rα largely fails to correct the inflammatory reprogramming of airway macrophages in T2-high asthma. Finally, by combining long-term ex vivo expansion with adoptive transfer of hematopoietic stem and progenitor cells (HSPCs), we show that anti-IL-4Rα treatment reprograms asthmatic bone marrow myeloid progenitors and thereby modulates subsequent responses to allergenic molds. Thus, our study provides clinically relevant insight into the mechanistic underpinnings, functional impact, and therapeutic modulation of trained immunity as an underappreciated component of asthma.