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The following is a summary of “Low-dose interleukin-2 in birch pollen allergy: a phase-2 randomized double-blind placebo-controlled trial,” published in the November 2024 issue of Allergy and Immunology by Rosenzwajg et al.
Regulatory T cells (Tregs) are pivotal in immune tolerance to allergens. Low-dose IL-2 (IL-2LD) activates Tregs.
Researchers conducted a prospective study to analyze IL-2LD efficacy in controlling clinical responses to allergen exposures.
The RHINIL-2 phase-2a randomized, double-blind, placebo-controlled trial included patients with birch pollen (BP) allergic rhinitis, 66% with asthma. All had a total nasal symptom score (TNSS) ≥5 after BP exposure in an environmental exposure chamber (EEC). Patients received 1 MUI/day of IL-2 (n=12) or placebo (n=12) for 5 days, then weekly for 4 weeks. Clinical responses to BP exposures were assessed by TNSS, rhinitis visual analogue scale (VAS), and spirometry. The primary endpoint was the TNSS area under the curve change from baseline to day 40 (TNSSΔAUC).
The results showed IL-2LD treatment significantly expanded Tregs, though TNSSΔAUC was not significantly different between IL-2 and placebo groups. Only the IL-2LD group had significant reductions in TNSS and VAS AUCs from baseline to day 40 (P=0.04 and P=0.01, respectively). Forced expiratory volume in 1 second/forced vital capacity (FEV1P) and forced mid-expiratory flow (FEF 25-75%) improved in the IL-2LD group compared to placebo at day 40 (P=0.04 and P=0.04, respectively). Due to short treatment duration, no effect was observed on specific IgE or IgG4 levels. No severe treatment-related adverse events (AEs) occurred.
The study concluded that IL-2LD was well-tolerated in patients with allergies, including those with asthma, supporting its potential for further development. More significant, extended studies are needed to assess IL-2’s therapeutic role in a fully therapeutic role in allergy.
Source: jacionline.org/article/S0091-6749(24)01181-3/abstract
