Salivary Immunoglobulin A, E, and G4 Levels Specific to Dermatophagoides pteronyssinus in Allergic Rhinitis Patients Treated With Subcutaneous Immunotherapy

Background Allergen-specific immunotherapy (AIT) is an effective treatment for allergic rhinitis (AR). During the course of AIT, many biomarkers in body fluids change. It is necessary to find effective indicators of AIT. Objective To examine levels of salivary immunoglobulin A, E, and G4 (IgA, IgE, and IgG4, respectively) specific to Dermatophagoides pteronyssinus (Dp-IgA, Dp-IgE, and Dp-IgG4, respectively) and their changes in AR patients undergoing subcutaneous immunotherapy (SCIT). Methods This study included 82 patients with AR sensitized only to Dp and 14 healthy controls. Among patients with AR, 30 patients were not treated with specific immunotherapy (group A), while the remainder (n = 52) received house dust mite SCIT in the up-dosing phase (n = 27; group B) or the maintenance treatment phase (n = 25; group C). Dp-IgA, Dp-IgE, and Dp-IgG4 levels in the saliva were measured using the enzyme-linked immunosorbent assay. Clinical symptoms, concomitant medication, and the Rhinoconjunctivitis Quality of Life Questionnaire score were recorded and correlated with immunoglobulin levels. Results Salivary Dp-IgG4 and Dp-IgA levels were significantly lower in AR patients than in healthy controls (P < .001 for both), while Dp-IgE levels were significantly higher (P < .001). SCIT resulted in sustained increases in Dp-IgG4 and Dp-IgA in the maintenance phase compared to the up-dosing phase (P < .001 for both), whereas Dp-IgE only increased in the up-dosing phase (P = .004, P < .0125). There was no correlation between the different salivary immunoglobulins and clinical scores during SCIT. Conclusions This study shows that allergen-specific IgE levels are increased in the saliva of sensitized patients, suggesting that measuring salivary IgE testing should be further considered for the diagnosis of AR. Moreover, allergen-specific IgA and IgG4 in the saliva, which may play protective roles against allergy, may serve as objective indicators for evaluating treatment response to SCIT. However, none of the immunoglobulin reflects subjective symptoms.