Evaluation of some immune mediators (IL-16, IgE and eosinophils) as diagnostic markers for COVID-19

Aim: To evaluate clinical applicability of immune mediator's interleukin-16, immunoglobulin E along with eosinophil count in diagnosing COVID-19 and determining its severity.

Materials and Methods: Cross-sectional case-control study was conducted at Al-Najaf General Hospital, Najaf, Iraq between March and August 2024. 120 participants: 60 confirmed COVID-19 cases and 60 healthy controls which matched cases in terms of age and sex. Data collected through direct interviews and hospital records; laboratory investigations were performed following standard protocols. Serum analysis: Serum levels of IgE and IL-16 were determined using an automated system and enzyme-linked immune sorbent assay (ELISA).

Results: A significant difference in levels of immune markers between COVID-19 group and healthy controls. Eosinophil count significantly higher in patients than in controls (105±64 cells/ml vs. 78±22 cells/ml, P<0.001). IgE levels in patients were markedly elevated compared to controls (788±98 UI/ml vs. 204±122 UI/ml, P<0.001). IL-16 levels in patients were double of controls (12.8±3.9 pg/ml vs. 6.2±2.9 pg/ml, P<0.01). Logistic regression analysis indicated that elevated levels of IL-16, IgE, and eosinophils were significantly associated with an increased risk of severe COVID-19, with IL-16 showing a particularly strong association (odds ratio=1.7, P<0.001). Sensitivity values were 0.74, 0.48, and 0.85 for eosinophils, IgE, and IL-16, while specificity values were 0.66, 0.58, and 0.72.

Conclusions: Findings underscore probable implication of immune mediators in respect, more especially IL-6, as biomarkers for COVID-19 severity and diagnosis.