Nasal allergen-neutralizing antibodies correlate closely with tolerated intranasal allergen challenge dose following grass pollen subcutaneous immunotherapy in patients with local allergic rhinitis.

Abstract

Local allergic rhinitis (LAR) is defined by chronic nasal symptoms, absence of atopy, positive nasal allergen challenge (NAC) and a good response to subcutaneous allergen immunotherapy (SCIT). We sought to investigate SCIT capacity to induce local and systemic blocking antibodies in LAR patients. A RDBPC study of grass SCIT was performed, with participants receiving either SCIT (Group A; n = 10) or placebo (Group B; n = 14) in the first 6 months. Both groups subsequently received SCIT for 12 months at Year 2. Nasal and serum antibodies (IgG₄, IgA₁ and IgA₂) and their inhibitory capacity were measured at multiple timepoints. The allergen concentration tolerated increased significantly at 6 months (Group A; p = .047) and 24 months (Group B; p = .049) compared with baseline and persisted until the end of the study. Induction of serum sIgA₁ to Phl p was seen in Groups A and B, albeit the former being induced earlier (1.71-fold, p = .027). A significant induction in sIgG₄ to Phl p 1 and 5 was observed in serum of Group A (p = .047 and p = .0039) and sIgA₂ to Phl p in Group B (p = .032 and p = .0098) at 18 and 24 months, respectively. Both local and systemic blocking antibodies can inhibit allergen-IgE complexes binding to CD23 on B cells, and this correlated with level of allergen tolerated intra-nasally in Group A (serum; 𝜌 = -.47, p = .0006, nasal; 𝜌 = -.38, p = .0294). Grass pollen SCIT induced functional systemic blocking antibodies that correlate with the concentration of allergen tolerated following NAC, highlighting their potential as a biomarker of SCIT in LAR.