Evaluation of İFN-gamma, IL-4, IL-10, eosinophilic cationic protein levels in tear in patients with allergic conjunctivitis

Introduction: Allergic conjunctivitis (AC) is one of the most common allergies in the pediatric age group and its frequency is increasing worldwide. It significantly affects the quality of life of patients by causing symptoms such as redness, itching, chemosis, and discharge. Tear is a liquid that covers the surface of the eye and helps to protect the eye, containing many cells, proteins and molecules. In studies on eye diseases, tear samples are frequently used due to their easy access and collection, and collection with a less invasive method. Studies have shown that different cytokines and cytokine groups play an important role in the pathogenesis of AC. Although tear cytokine studies have increased in recent years, many new studies are still needed. In our study, we planned on tear cytokines and preferred cytokines that have different effects on allergic mechanisms. We aimed to examine allergic inflammation from different aspects via IL-4 as a Th2-derived cytokine, IFN-Gamma as a Th1-derived cytokine, IL-10 as an anti-inflammatory and ECP as an eosinophil-derived protein, and we also aimed to evaluated the correlation between this cytokines and serum parameters to correlate these cytokines with serum parameters that were previously checked in outpatient follow-ups. Material and Methods: A total of 27 patients diagnosed with AC in our Bezmiâlem Pediatric Allergy Diseases Outpatient Clinic between April 2022 and October 2022, and 27 healthy children without any chronic disease or additional disease who came to the Ophthalmology Outpatient Clinic as a control group were included in the study. Tear samples were collected with Schirmer filter papers according to the Schirmer 1 test protocol and stored at -40 degrees. The samples were brought to room temperature in our hospital's biochemistry laboratory and were selected the samples with sufficient protein amount and included in the study. Selected samples were studied in accordance with the ELISA kit protocol. Calculations were made with the protein amounts of each sample by drawing the standard graph. Results: There was no significant difference between the case and control groups participating in the study in terms of gender and mean age. There was only a significant increase in IFN-Gamma among the pre-treatment and post-treatment results in the case group. There was no significant difference between other cytokines. There was a significant increase in IL-4 and ECP levels between the pretreatment and control group results. There was a significant difference in IL-4, ECP, IFN-Gamma between the post-treatment, and control group results. In IL-10 results, no significant difference was observed in any group. There was no correlation between IL-4, ECP, IFN-Gamma and IL-10 levels and Total IgE and percentage of eosinophils. Conclusion: The fact that IL-4 and ECP were higher in the patient group than in the healthy group supports Th2-mediated IgE-mediated type 1 reaction and inflammation due to eosinophilic infiltration in allergic inflammation. We observed that they were not effective parameters in evaluating response to treatment. Despite clinical improvement after treatment, the fact that IL-4 and ECP levels were higher than the healthy group suggests that there may still be ongoing subclinical inflammation in the conjunctiva. We observed that IFN-Gamma is not an effective parameter in proving allergy, but is a meaningful test in evaluating the therapeutic response. No significant results were shown for IL-10 in the study. There was no significant correlation between cytokine levels and serum parameters. Keywords: Allergic Conjunctivitis, Tear, IFN-Gamma, IL-4, IL-10, Eosinophilic Cationic Protein