Evaluation of the concentration dynamics of allergen-specific secretory immunoglobulin A in saliva, interleukin 4 and interferon γ in blood serum as predictive biomarkers of the allergen immunotherapy efficacy

BACKGROUND: The only pathogenetic method for treatment of respiratory allergic diseases is allergen immunotherapy. Despite the fact that this method has been used for over a hundred years, its exact mechanisms continue to be studied, and predictive biomarkers that could optimize the selection of patients for therapy are lacking. AIM: To assess the clinical significance of changes in the levels of allergen-specific secretory immunoglobulin A in saliva, interleukin 4 and interferon γ in blood serum as predictive biomarkers of the allergen immunotherapy efficacy in patients with respiratory allergies. MATERIALS AND METHODS: A prospective, single-center study included patients with allergic rhinitis with/without asthma caused by sensitization to allergens of house dust mite and healthy volunteers. Patients in the treatment group received therapy with sublingual allergens of house dust mite for six months; the severity of clinical symptoms was assessed at control visits (before, after 2 and 6 months of therapy). Biomaterial was collected once from healthy volunteers and at every control visit from the patients of the treatment group to assess the concentrations of allergen-specific secretory immunoglobulin A in saliva, interleukin 4 and interferon γ in serum using the enzyme-linked immunosorbent assay. RESULTS: Both treatment and control groups included 10 adult volunteers, matched for age, gender, and baseline cytokine levels (p 0.05). The treatment group had a higher baseline level of allergen-specific secretory immunoglobulin A in saliva (p 0.001). All patients achieved clinical improvement after 6 months of therapy in relation to allergic rhinitis symptoms, patients with asthma achieved improvement after 2 months, this improvement was sustained throughout the observation period. Evaluation of biomarker changes showed a significant increase in the level of allergen-specific secretory immunoglobulin A in saliva by the 2nd month of treatment (p = 0.006), an increase in the concentration of interferon γ in the serum by the 6th month (p = 0.002). The concentration of interleukin 4 in the serum increased by the 2nd (p = 0.002) and decreased by the 6th (p = 0.002) month. The change in the concentration of allergen-specific secretory immunoglobulin A in saliva, interleukin 4 in serum did not correlate with the therapy efficacy, the change in the concentration of interferon γ correlated with the therapy efficacy after 6 months of therapy in relation to symptoms of allergic rhinitis (rs = −0.782; p = 0.012) and asthma (rs = 0.943; p = 0.017). CONCLUSION: The obtained results indicate that changes in the levels of Th1- and Th2-cytokines in the blood serum, induction of the synthesis of allergen-specific secretory immunoglobulin A in the oral cavity participate in the mechanisms of the sublingual allergen immunotherapy effect. The data of the correlation analysis, assessed at a two-month and six-month interval during allergen immunotherapy, allow us to identify changes in the concentration of interferon γ in the serum as potential predictive biomarker of allergen immunotherapy efficacy.