The research team, led by investigators at Virant Diagnostics Laboratory and the Institute for Asthma and Allergy in Maryland, followed 32 peanut-allergic children aged 4 to 18 who underwent peanut oral immunotherapy at a single clinic between 2021 and 2025. Sixteen of the children had Ara h 2-specific IgE levels of 40 kU/L or higher — a threshold associated with severe, clinically significant peanut allergy — while the other 16 had lower values. Rather than the faster escalation schedules used in commercial protocols, every participant started at a mere 0.1 milligrams of peanut protein, roughly a ten-thousandth of a peanut’s worth, and climbed through 18 dose levels over a prolonged up-dosing phase lasting one to two years, with clinic visits spaced 14 to 28 days apart or longer.

The clinical results defied expectations for the high-risk group. By 24 months, 68.8 percent of the children with high Ara h 2-IgE had achieved effective desensitization, defined as safely consuming at least 300 milligrams of peanut protein daily — a benchmark estimated to shield against more than 95 percent of accidental exposures, which typically involve amounts well below 100 milligrams. The lower-IgE group fared no better and no worse, with 62.5 percent reaching the same goal. Nine children escalated further, exceeding 1,000 milligrams per day, and one tolerated up to 7,000 milligrams. Safety data were equally reassuring: despite the forbidding baseline antibody levels, only one severe reaction occurred in each subgroup across the entire study, no child discontinued treatment because of adverse events, and no cases of eosinophilic esophagitis emerged.

Alongside the clinical outcomes, the researchers pursued a question that has long frustrated the allergy field: can laboratory measurements tell whether immunotherapy is actually working inside a patient? No validated biomarker currently exists to predict who will succeed with oral immunotherapy or to monitor the desensitization process as it happens. The gold standard for measuring food allergy, the double-blind placebo-controlled oral food challenge, is resource-hungry and carries its own risks, so a blood test that captures immune change in real time would be transformative for both research and routine care.

The team focused on two candidate measures. The first is the basophil activation test, or BAT, a flow-cytometry technique that measures how strongly a patient’s basophils — the white blood cells that unleash histamine in allergic reactions — display the CD63 surface marker when exposed to escalating concentrations of peanut protein in a test tube. Because it interrogates effector-cell reactivity directly rather than merely quantifying antibodies, BAT offers a functional window into allergic potential. The second measure is the ratio of allergen-specific IgE, the antibody class that drives allergic reactions, to allergen-specific IgG4, a so-called blocking antibody that competes with IgE for allergen binding and is thought to dampen responses during immunotherapy.

What emerged was a dynamic, biphasic picture that static snapshots would have missed entirely. Basophil reactivity did not simply fade during treatment; it first spiked during the early up-dosing months, between months two and six, before progressively and significantly declining thereafter. Mixed-effects models accounting for repeated measurements within each participant confirmed a highly significant overall change over time, with suppression becoming statistically robust at 19 to 24 months and deepening further at 25 to 36 months. Even more telling, the activation threshold shifted stepwise upward: significant blunting of basophil responses appeared first at low peanut concentrations, then at intermediate doses, and finally even at the highest concentration tested — meaning that by the end of the study, a child’s basophils needed far more allergen to fire than they had at the start.

When the researchers compared the most recent BAT area under the curve during months 13 to 36 with each child’s maximum tolerated daily dose, a value below 100 was significantly associated with effective desensitization, achieving a sensitivity of 89.5 percent. Receiver operating characteristic analysis yielded an area under the curve of 0.784 for the continuous measure. The antibody story ran in parallel: peanut- and component-specific IgE rose transiently in the first months of therapy — at one point, 100 percent of participants exceeded 50 kU/L for peanut IgE — before drifting downward, while specific IgG4 climbed early and kept climbing, driving the IgE/IgG4 ratio down throughout treatment. A ratio below 50, reached by 72 percent of participants at 13 to 18 months, showed strong discriminatory performance with an ROC value of 0.836.

The authors are careful about what these thresholds can and cannot do. Baseline BAT and baseline IgE bore no relationship to eventual desensitization, and exploratory time-lagged analyses — asking whether biomarker values at 13 to 18 months predicted success at 19 to 24 months — did not establish prospective predictive power, with confidence intervals too wide to be conclusive. Both cutoffs were derived and tested within the same small cohort, a practice the researchers themselves flag as likely optimistic. The study was also single-center, retrospective, and lacked a control group, and it required participants to have completed treatment and at least two BAT measurements, a design that may have excluded early dropouts and inflated success rates. Desensitization was judged from routinely consumed doses rather than blinded food challenges.

Even so, the conceptual message may prove the study’s most durable contribution. The traditional approach to assessing food allergy — a single IgE number drawn before treatment begins — appears fundamentally limited, because the most informative signals are trajectories, not starting points. In this cohort, children whose IgE remained elevated at two years were nonetheless clinically desensitized, showing that serologic antibody decline lags behind functional improvement, sometimes by a wide margin. A clinician relying on IgE alone mid-treatment might wrongly conclude that therapy was failing when basophil suppression and rising IgG4 told a very different story.

For the growing number of families considering peanut oral immunotherapy, the findings carry a practical takeaway: patients with frighteningly high antibody levels are not automatically excluded from treatment, provided the protocol is paced to match their risk. Whether slow escalation genuinely improves safety compared with faster regimens, and whether longitudinal biomarker monitoring can be validated against standardized challenges in independent cohorts, remain open questions that the authors say must precede any clinical implementation. But the vision is clear — a future in which a series of blood draws, tracking basophils and antibody ratios over months, could give allergists and anxious parents a real-time readout of the immune system slowly learning to tolerate the very food that once threatened it.

Subject of Research: Longitudinal basophil activation testing and antibody biomarkers during low-dose, slow-escalation peanut oral immunotherapy in children with high Ara h 2-specific IgE

Article Title: Longitudinal basophil activation testing for assessing response to low-dose initiation, slow-escalation peanut oral immunotherapy in patients with high Ara h 2-sIgE

Article References: Chen, J., Yu, J. J., Yu, J., Wan, L., Chiao, J., Economides, A., Han, D., & Li, H. H. (2026). Longitudinal basophil activation testing for assessing response to low-dose initiation, slow-escalation peanut oral immunotherapy in patients with high Ara h 2-sIgE. Frontiers in Allergy, 7, Article 1902025. https://doi.org/10.3389/falgy.2026.1902025

Image Credits: AI Generated

DOI: 10.3389/falgy.2026.1902025

Keywords: peanut allergy, oral immunotherapy, basophil activation test, Ara h 2, desensitization, biomarkers, IgG4, food allergy, allergen immunotherapy, pediatrics, flow cytometry, anaphylaxis

The research, led by Ran Zhao, Na Dong, and Xiaoyan Dong of Shanghai Children’s Hospital at Shanghai Jiao Tong University, together with Weilong Zhang and Shifang Ren of Fudan University’s NHC Key Laboratory of Glycoconjugates Research, examined how immunoglobulin G glycosylation changes during the course of subcutaneous allergen immunotherapy. Immunoglobulin G, the most abundant antibody in human plasma, carries a conserved N-glycan at a specific asparagine residue in its Fc region. This glycan is not decorative. Its composition, including the number of terminal galactose and sialic acid residues and the presence of a bisecting N-acetylglucosamine, directly modulates the antibody’s ability to engage Fc gamma receptors on immune cells and thereby determines whether IgG exerts pro-inflammatory or anti-inflammatory effects.

Decades of work have established that IgG glycosylation shifts measurably in inflammatory conditions. Reduced galactosylation and sialylation are hallmarks of active rheumatoid arthritis, and intravenous immunoglobulin preparations owe part of their anti-inflammatory activity to a small sialylated fraction. Because successful allergen immunotherapy is thought to depend on regulatory B cells producing IgG4 and on interleukin-10-driven tolerance mechanisms, the researchers reasoned that the glycan profile of plasma IgG might track the immunological state of patients undergoing the therapy, and might even flag those at risk of adverse reactions before treatment begins.

To test this, the team enrolled 37 patients with allergic asthma or allergic rhinitis who were beginning subcutaneous immunotherapy, largely against house dust mite allergens such as Dermatophagoides pteronyssinus. Of these, 26 patients were followed longitudinally at three time points: before treatment, at the initiation of the maintenance phase, and after more than six months of maintenance injections. Plasma samples were collected at each visit, IgG was purified, and its N-linked glycans were released and profiled by ultra-performance liquid chromatography, a high-resolution technique that separates glycans into discrete chromatographic peaks, each corresponding to a defined glycan structure that can be quantified as a percentage of total glycan signal.

The longitudinal data revealed a coherent remodeling of the IgG glycome as tolerance developed. Total galactosylation and sialylation of IgG glycans rose gradually across the treatment course, while the proportion of bisecting glycans, structures bearing a bisecting N-acetylglucosamine added by the enzyme GnT-III, declined. This pattern is consistent with a shift toward the anti-inflammatory, sialylated IgG species associated with immune regulation, and it provides a mechanistic readout of the tolerance process that clinicians have previously had to infer indirectly from symptom scores and medication use.

The more striking result emerged when the researchers compared baseline samples from patients who later experienced adverse reactions with those who tolerated the therapy. Patients destined to react showed significantly elevated levels of the glycan peak designated GP6, reduced levels of peaks GP18 and GP23, lower overall galactosylation and sialylation, and increased bisecting glycans before receiving any treatment. In other words, the pretreatment glycan signature of reactive patients resembled a pro-inflammatory state, with IgG skewed toward agalactosylated, asialylated, and bisected structures known to enhance antibody-dependent effector functions through activating Fc gamma receptors.

To translate these differences into a clinically usable predictor, the team performed receiver operating characteristic analysis, a standard method for evaluating how well a biomarker discriminates between two groups across all possible thresholds. A combined model built from multiple glycan features achieved an area under the curve of 0.863 for predicting adverse reactions, a level of discrimination that, if validated, would substantially outperform the clinical history and skin testing alone that currently guide risk assessment. Because the measurement requires only a small plasma sample drawn before therapy starts, the authors describe the approach as minimally invasive and mechanism-based, offering a route to pretreatment risk stratification that could allow clinicians to adjust dosing schedules, intensify monitoring, or select alternative management for high-risk individuals.

The implications extend beyond the allergy clinic. Glycosylation is increasingly recognized as a sensitive barometer of immune status, and this study adds allergen immunotherapy to the growing list of contexts in which IgG N-glycan profiling carries genuine predictive power. The work also connects to a broader mechanistic picture: regulatory T cells and regulatory B cells, interleukin-10 signaling, and the IgG4 class-switching that characterizes successful immunotherapy all intersect with the glycan machinery of antibody-producing cells. A glycan biomarker therefore does not merely correlate with outcomes; it plausibly reflects the underlying immunological shift from a Th2-dominated allergic phenotype toward tolerance.

The authors are careful to note the limitations of the study. The cohort of 37 patients, drawn from a single pediatric hospital, is modest in size, and the findings require validation in larger, multicenter populations before glycan profiling can enter routine practice. The published version remains subject to final editorial updates, and the researchers emphasize that further work is needed to standardize the chromatographic assay, define cut-off values, and test whether the same signatures apply to adults, to other allergen extracts, and to sublingual as well as subcutaneous routes of administration. Still, the combination of a strong longitudinal signal, a clear baseline distinction between tolerant and reactive patients, and a respectable area under the curve makes this one of the more compelling biomarker candidates to emerge in the allergy field in recent years.

If multicenter validation confirms the result, the practical consequences could be significant. Allergen immunotherapy is underused relative to its disease-modifying potential, partly because of safety concerns and the burden of monitoring patients through a months-long buildup phase. A simple blood test that identifies patients at elevated risk of reactions before the first injection would allow the therapy to be offered more confidently to suitable candidates and tailored more cautiously to those at risk. It would also open a window on the biology of tolerance itself, letting researchers watch, in molecular detail, as the immune system learns to accept what it once attacked. For a field long guided by trial and error, the sugars on a single antibody may finally provide the objective compass that clinicians have been missing.

Subject of Research: IgG N-glycan profiling as a predictive biomarker for adverse reactions in allergen-specific immunotherapy

Article Title: Plasma IgG glycan dynamics predict adverse reactions in allergen immunotherapy

Article References: Plasma IgG glycan dynamics predict adverse reactions in allergen immunotherapy. (n.d.). https://doi.org/10.1186/s12014-026-09627-y

Image Credits: AI Generated

DOI: 10.1186/s12014-026-09627-y

Keywords: allergen immunotherapy, IgG glycosylation, N-glycans, allergic asthma, allergic rhinitis, biomarkers, adverse reactions, immune tolerance, Clinical Proteomics, ultra-performance liquid chromatography, ROC analysis, glycomics