Seroprevalence of Epstein-Barr Virus Antibodies and Complement C3/C4 Levels in Immunocompromised (Malignant Tumors and Organ Transplant Recipients) Patients

This cross-sectional study (4 Oct 2024–5Mar 2025) assessed Epstein-Barr virus (EBV) seroprevalence and complement activity in 100 immunocompromised patients (80 cancers and 20 kidney transplant) versus 50 healthy blood donors at Baqubah Teaching Hospital. Serum IgG/IgM antibodies were quantified by ELISA, alongside hematologic indices and complement components C3 and C4. EBV exposure was substantially higher in the patient group: 17% were IgG-positive and 4% IgM-positive, compared with only 3% IgG-positivity and 0% IgM-positivity in controls, underscoring greater past and recent infection in immunocompromised hosts. Hematologic profiles reflected this vulnerability. Patients exhibited significantly lower haemoglobin (11.57 ± 0.19 g/dL vs. 12.75 ± 0.16 g/dL; p = 0.001) and lymphocyte counts (1.54 ± 0.07 × 10³ µL⁻¹ vs. 1.89 ± 0.13 × 10³ µL⁻¹; p = 0.02), alongside markedly depressed total white blood cell counts (4.90 ± 0.18 × 10³ µL⁻¹ vs. 9.90 ± 0.29 × 10³ µL⁻¹; p = 0.001). Red blood cell counts were paradoxically higher in patients (4.11 ± 0.10 × 10⁶ µL⁻¹ vs. 3.65 ± 0.10 × 10⁶ µL⁻¹; p = 0.001), while platelet numbers did not differ. Complement analysis revealed a pronounced rise in C3 among patients (116.68 ± 2.17 mg/dL) relative to controls (91.26 ± 3.63 mg/dL; p = 0.001), suggesting enhanced innate immune activation; C4 levels remained comparable (31.46 ± 0.89 mg/dL vs. 31.27 ± 1.11 mg/dL; p = 0.801). In conclusion, the data highlight a significantly greater EBV burden in tumour and transplant recipients, accompanied by characteristic shifts in blood counts and elevated C3.