Evaluation of interleukin-35 and interleukin-27 in allergic conjunctivitis and associated allergies before and after allergen-specific immunotherapy

Background/aim
While interleukin (IL)-35 has been identified as a novel immunosuppressive and anti-inflammatory cytokine, IL-27 has both inflammatory and anti-inflammatory functions. Allergen-specific immunotherapy is the most excellent form for custom-tailored treatment of allergic diseases. The aim of this study is to determine the role of IL-35 and IL-27 and the protective role of allergen-specific immunotherapy in allergic conjunctivitis alone or associated with other allergies.
Patients and methods
The present study enrolled 30 patients who were referred to the Allergy Lab, at the Research Institute of Ophthalmology, Giza, Cairo, Egypt. Patients were divided into two groups (15 each); patients complaining of allergic conjunctivitis alone (group 1) and patients who were suffering from allergic conjunctivitis associated with allergic rhinitis and/or allergic bronchitis (group 2). In addition, 15 healthy individuals served as a control group (group 3). Allergen SIT was prepared from natural allergenic extracts from some different crude materials causing allergy, such as pollens, animal hairs, house dust, molds, nicotine, and feathers. Group 1 was treated with local conjunctival immunotherapy as eye drops, while group 2 was treated with subcutaneous immunotherapy for 36 months. Serum levels of IL-35 and IL-27 were measured using the enzyme-linked immunoassay technique before and after immunotherapy.
Results
The present results showed significant decreases in serum levels of IL-35 and IL-27 (146.4 and 13.2 pg/ml, respectively) in all 30 allergic patients before immunotherapy than controls (235.0 and 50.4 pg/ml). However, IL-35 and IL-27 showed a significant increase (478.8 and 42.6 pg/ml, respectively) in all patients after receiving their immunotherapy either as eye drops or as subcutaneous injections when compared before starting immunotherapy. Moreover, insignificant changes were obtained between local and subcutaneous immunotherapy in the level of IL-35, while IL-27 showed a significant increase (<0.05) in the subcutaneous group than the eye drops group. The present results showed a positive excellent correlation between IL-35 and IL-27 after immunotherapy (=0.709, <0.001), while no correlation before immunotherapy (=0.334, =0.063).
Conclusions
Allergic diseases are associated with significant lowered serum levels of IL-35 and IL-27. Allergen-specific immunotherapy significantly increases serum levels of IL-35 and IL-27 confirming the role of IL-35 and IL-27 in allergic diseases and proved that allergen-specific immunotherapy increases their induction.