Correlation between Serum Levels of Some Immunological Biomarkers and Severity of Idiopathic Immune Thrombocytopenia

Abstract

Background: Idiopathic immune thrombocytopenia (ITP) is an autoimmune hematological disorder characterized by a platelet count below 100 × 10⁹/L due to immune-mediated destruction and impaired production of platelets. Immune regulatory molecules, including cytokines and immune checkpoint markers, play a vital role in modulating the inflammatory environment and immune tolerance. Dysregulation in the expression or function of these biomarkers contributes significantly to disease pathogenesis and progression. Aim: The objective of this study was to evaluate the correlation between serum levels of five immunological markers—TNFAIP3, CD28, CTLA4, FoxO3, and IL-39—and the severity of ITP in Iraqi patients, with an emphasis on diagnostic utility and inter-marker relationships. Methods: This case-control study enrolled 180 participants, divided into three groups: newly diagnosed ITP patients (ND, n = 62), medicated ITP patients (MD, n = 58), and healthy controls (HC, n = 60). Serum concentrations of TNFAIP3, CD28, CTLA4, FoxO3, and IL-39 were quantified using ELISA. Statistical analysis was conducted using GraphPad Prism v9.0..Results: The study found significantly elevated levels of TNFAIP3 (928 ± 127.7 ng/mL), CD28 (17.5 ± 1.28 ng/mL), CTLA4 (147.5 ± 29.34 ng/mL), FoxO3 (711.7 ± 45.17 ng/mL), and IL-39 (12.98 ± 2.98 ng/mL) in ND patients compared to MD patients and HC (p < 0.001). IL-39 levels were notably reduced in the MD group (4.61 ± 0.392 ng/mL) but remained elevated in ND patients, suggesting its potential as an early-stage biomarker. ROC analysis demonstrated exceptional diagnostic performance for CD28, CTLA4, FoxO3, and IL-39, with AUC values of 1.0 in ND patients, achieving 100% sensitivity and specificity at optimal cut-off points. TNFAIP3 showed excellent discriminatory power in ND patients (AUC = 1.0), but limited diagnostic value in MD cases (AUC = 0.537). Pearson correlation analysis revealed strong positive correlations among most biomarkers, especially between TNFAIP3 and FoxO3 (r = 0.938), CTLA4 (r = 0.934), and CD28 (r = 0.893), indicating coordinated immunoregulatory dysfunction in ITP pathogenesis. Conclusion: The findings highlight that TNFAIP3, CD28, CTLA4, FoxO3, and IL-39 are significantly associated with disease onset and severity in ITP. These markers offer strong diagnostic value, especially in distinguishing newly diagnosed cases, and may serve as potential targets for immunomodulatory therapies. The observed inter-marker correlations further suggest a complex but coordinated dysregulation of immune responses in ITP, meriting further mechanistic studies.

Keywords

• ITP
• Immunological markers
• ELISA