Allergic rhinitis (AR) is a public health problem with high prevalence worldwide. We evaluated levels of specific IgE, IgA, and IgG4 antibodies to the Dermatophagoides pteronyssinus (Dpt) house dust mite and to its major allergens (Der p1 and Der p2) in serum and saliva samples from allergic and nonallergic children. A total of 86 children were analyzed, from which 72 had AR and 14 were nonallergic healthy children. Serum IgE and serum/salivary IgG4 levels to Dpt, Der p1, and Der p2 were higher in allergic children whereas serum/salivary IgA levels to all allergens were higher in nonallergic children. IgE levels positively correlated with IgG4 and IgA to all allergens in allergic children, while IgA levels negatively correlated with IgG4 to Dpt and Der p1 in nonallergic children. In conclusion, mite-specific IgA antibodies predominate in the serum and saliva of nonallergic children whereas mite-specific IgE and IgG4 are prevalent in allergic children. The presence of specific IgA appears to have a key role for the healthy immune response to mucosal allergens. Also, specific IgA measurements in serum and/or saliva may be useful for monitoring activation of tolerance-inducing mechanisms during allergen specific immunotherapeutic procedures, especially sublingual immunotherapy.

All children undergoing SLIT showed clinical improvement, but a long-term reduction in symptom/medication scores with modulation of mucosal/systemic antibody responses were seen only in active groups (DPT and DPT+MRB).

BackgroundThis study aimed to evaluate the clinical efficacy and mucosal/systemic antibody response changes after sublingual immunotherapy (SLIT) using Dermatophagoides pteronyssinus (Dpt) allergens with or without bacterial extracts in mite-allergic Brazilian children.MethodsOne-hundred and 2 patients presenting allergic rhinitis with or without asthma were selected for a randomized double-blind, placebo-controlled trial and distributed into 3 groups: DPT (Dpt allergen extract, n = 34), DPT + MRB (Dpt allergen plus mixed respiratory bacterial extracts, n = 36), and Placebo (n = 32). Clinical evaluation and immunological analyses were carried out before and after 12 and 18 months of treatment, including rhinitis/asthma symptom and medication scores, skin prick test (SPT) to Dpt extract, and measurements of Dpt-, Der p 1-, Der p 2-specific IgE, IgG4, and IgG1 in serum and -specific IgA in saliva and nasal lavage fluid.ResultsClinical results showed a significant decline in rhinitis/asthma symptom scores in all groups, but medication use decreased only in active DPT group at 12 months. SPT results showed no significant changes and SLIT was generally safe, with no severe systemic reactions. SLIT using Dpt allergen alone induced increased serum IgG4 levels to Dpt, Der p 1 and Der p 2, and increased serum IgG1 and salivary IgA levels to Dpt and Der p 1. SLIT using DPT+MRB was able to decrease IgE levels, particularly to Der p 2, to increase salivary IgA levels to Der p 1, but had no changes on specific IgG4 and IgG1 levels.ConclusionsTherefore, SLIT seems to be effective in ameliorating clinical symptoms, but only active SLIT was able to modulate the mucosal and systemic antibody responses. These findings support the role of specific serum IgG4 and IgG1, in addition to salivary IgA, as protective or blocking antibodies as well as biomarkers of tolerance that may be useful for monitoring activation of tolerance-inducing mechanisms during allergen immunotherapy.

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