2025, Vol. 7, Issue 11, Part C

Methods: A case and control study were included among a study population of 400 probable incidents (400 controls matched 200 cases of respiratory tract infections) recruited through private clinics and public hospital in Babylon. Unstimulated saliva specimens were collected and submitted for analysis of Secretory immunoglobulin by the Immunoassay by the Immuno Max-Bride-ELS (Immuno Max-ELSZA; Enzymes Immuno Assay, Conway, MA, USA) and serum IgA concentrations were determined by immunoturbidimetry (Motra suspected SIgAD) using the Technolink ImmunoMax-Well-Serum test (Immuno Max-Well-S-Serum, Enzymed Immuno Assay, Conway, MA, USA). Clinical data such as antibiotic consumption, hospitalization and absenteeism from school/work were recorded.

Results: Median salivary Secretory immunoglobulin was significantly less in the cases (13.2 mg/dL, IQR 8.4-21.1) than that of controls (28.6 mg/dL, IQR 19.5-41.3; p<0.001). the results were the prevalence of low sIgA levels was 34.5% in cases and 9% in controls (p<0.001). However, Secretory immunoglobulin was more prevalent in cases (3.5%) than in the controls (0.5%; p=0.03). Oh - and low Secretory immunoglobulin was related to higher antibiotic use (91.3 vs 58.8%), hospitalization frequency (29 vs 9.1%) and absenteeism (median 14 vs 7 days; all p<0.001). Significant negative correlations were found between Secretory immunoglobulin levels and number of RRTI (r= - 0.62), antibiotic courses (r= - 0.54) and absenteeism (r= - 0.58) (all p<0.001). In the combination of serum and mucosal IgA deficiency the risk of serious infections was greatest (62.5%).

Conclusion: Low mucosal Secretory immunoglobulin was highly associated with the risk and severity of respiratory tract infections among pediatric and adult population living in Babylon. These results support the importance of salivary Secretory immunoglobulin as an accessible and useful biomarker to determine persons at high risk for recurrent infections. The use of Secretory immunoglobulin measurement in the primary care setting would offer early identification and selective management of mucosal immune deficiency in Iraq.