Ragweed SLIT-Tablets Induce Similar Patterns of Allergen-Specific IgE and IgG4 Responses in Children and Adults with Allergic Rhinoconjunctivitis

New pediatric data now allows for comparison of treatment-induced serological immune responses to ragweed sublingual immunotherapy (SLIT)-tablets between children and adults with allergic rhinitis with or without conjunctivitis (AR/C). Subjects with ragweed AR/C with or without asthma were randomized to daily ragweed SLIT-tablets or placebo ≈12-20 (pediatric) or ≈16 weeks (adult) before ragweed pollen season in two double-blind, international trials, one in children aged 5-17 years (NCT02478398; N=1025) and one in adults aged 18-50 years (NCT00770315; N=784). The primary endpoint was the total combined daily symptom and medication scores (TCS) during peak season. Serum IgE and IgG4 to Ambrosia artemisiifolia at baseline, pre-season, and end-of-season were evaluated. Relative TCS improvements with ragweed SLIT-tablets (12 Amb a 1-U dose) versus placebo were 38% and 24% in the pediatric and adult trials, respectively (P≤0.002 vs placebo). Specific IgE and IgG4 levels markedly increased from baseline to pre-season in children (2.5-fold and 3-fold, respectively) and adults (4-fold and 5-fold, respectively) receiving ragweed SLIT-tablet and plateaued by end-of-season. In children and adults receiving placebo, specific IgE and IgG4 levels remained similar from baseline to pre-season but increased at the end-of-season after natural exposure to Ambrosia artemisiifolia. The increase in IgE was more pronounced in children compared with adults. Ragweed SLIT-tablets induced similar specific IgE and IgG4 patterns in children and adults, although the overall fold increase in specific IgE versus placebo appeared higher in adults. These results support the concept that mechanisms of allergy immunotherapy disease-modification are similar in both populations.