Exploring the immunological underpinnings of allergic conjunctivitis: the role of CD4 + T Cells and SLAM expression in ocular surface disease.

Background: Allergic conjunctivitis is a common ocular disease characterized by inflammation of the conjunctiva, often associated with environmental allergens. CD4 + T cells and signal lymphocyte activation molecule (SLAM) expression has been implicated in the pathogenesis of allergic conjunctivitis, but their roles and interactions remain unclear.

Methods: This prospective cross-sectional observational study enrolled 100 participants, 50 with allergic conjunctivitis and 50 healthy controls, to investigate the relationship between peripheral blood CD4 + T cells, SLAM expression, and allergic conjunctivitis. Participants were evaluated using the Aston university allergy questionnaire (AUAQ), ocular surface disease index (OSDI), and dry eye questionnaire (DEQ-5). Peripheral blood mononuclear cells were isolated and analyzed for SLAM expression on CD4 + T cells using flow cytometry. Total serum IgE levels were measured using ELISA.

Results: The allergic group demonstrated significantly higher AUAQ, OSDI, and DEQ-5 scores compared to the control group, indicating a more severe allergic and ocular surface disease burden. Flow cytometry analysis revealed a significant increase in SLAM expression on CD4 + T cells in the allergic group (22.6% ± 5.3%) compared to the control group (15.2% ± 4.7%) (p < 0.001). Total serum IgE levels were also significantly higher in the allergic group (255.3 ± 131.2 IU/mL) compared to the control group (36.7 ± 19.8 IU/mL) (p < 0.001). Spearman's rank correlation analysis indicated significant correlations between AUAQ and OSDI scores (R = 0.38, p < 0.001), and between TBUT and OSDI scores (R = 0.21, p = 0.008), suggesting that reduced tear film stability is associated with more severe ocular surface symptoms.

Conclusion: The study findings suggest a significant association between allergic symptoms, ocular surface disease, and immunological markers in individuals with allergic conjunctivitis. The increased SLAM expression on CD4 + T cells and elevated total serum IgE levels in the allergic group may play a pivotal role in the pathophysiology of allergic conjunctivitis. These insights could inform the development of targeted therapies that address both the allergic and ocular surface components of the disease, potentially improving management and outcomes for patients with allergic conjunctivitis.