Correlation of sPD1 with Procalcitonin and C-Reactive Protein Levels in Patients with Sepsis

Sepsis results from dysregulated host responses to infection, and it is a major cause of mortality in the world. Co-inhibitory molecules, such as PD-1, play a critical role in this process. Considering the lack of information on the relation between sPD1 and sepsis, the present study aimed to examine the sPD1 level in septic patients and evaluate its correlation with procalcitonin (PCT) and C-reactive protein (CRP) levels.

This descriptive cross-sectional study consisted of three groups, including septic patients (n=15), suspected of sepsis (n=15), and healthy subjects (n=15). White blood cells (WBCs) and platelet (PLT) counts are evaluated. The serum levels of CRP, PCT, and sPD1 were measured by immunoturbidimetric assay, electro- chemiluminescence technology, and the enzyme-linked immunosorbent assay (ELISA), respectively.

Our study indicated that there was a significant difference in WBC and PLT counts between the septic group compared to suspected and control groups (P<0.001, P<0.01, respectively). The CRP level was significantly higher in septic compared to suspected and control groups (P<0.001). There was also a significant difference between the PCT level in septic and suspected groups in comparison with the controls (P<0.001, P<0.01). The sPD1 level was significantly higher in septic patients compared to suspected and control groups (P<0.001). In septic patients, sPD1 levels were correlated positively with the CRP and PCT levels.

Overall, sPD1 correlation with inflammatory markers, might propose it as a potential biomarker to sepsis diagnosis. However, the clinical application of serum sPD-1 testing in patients with sepsis requires further investigation.