Combining CD64 and CD123 Biomarkers for Sepsis Early Diagnosis and Severity Assessment via PD-L1 Antibody Affinity Microfluidic (PAAM) Chip in Trace Clinical Samples

Sepsis, a lethal organ dysfunction caused by a dysregulated host response to infection, is the leading cause of worldwide in-hospital mortality. However, the early diagnostic methods for sepsis are still urgent for guiding accurate antibiotic usage and improving the survival rate of the patients. Herein, we constructed a PD-L1 antibody affinity microfluidic (PAAM) chip for early sepsis diagnosis and severity assessment. The chip was used to capture PD-L1-expressing leukocytes from whole blood samples obtained from healthy control (HC) volunteers (n = 15) and sepsis patients on day 1 (D1) and day 7 (D7) (n = 20), and there was a statistically significant difference between HC and sepsis patients (p < 0.0001), and the AUC was 0.96. However, there was no significant difference in the number of cells captured on-chip between sepsis patients on D1 and D7 (p = 0.16). Therefore, we performed immunofluorescence staining of PD-L1, CD64, and CD123 on the chip. The results showed that the combination of PD-L1, CD64, and CD123 for sepsis diagnosis had an AUC of 0.98, and there was a significant difference in PD-L1⁺/CD64⁺/CD123⁺ leukocytes between sepsis patients on D1 and on D7 (p < 0.0001). In conclusion, we found that the combination of multiple biomarkers was more precise and dependable for sepsis diagnosis and severity assessment.