A Point-of-Care Diagnostic Platform for Detecting Host Immune Activation due to Infections: Cytocapture of Biomarkers In Situ (CyBIS).

Abstract

The prompt diagnosis of internal infections is an important, but surprisingly difficult, component of healthcare. Existing clinical and laboratory tests, such as complete blood counts, are low accuracy (~70%), time consuming (>90 min), and require expensive blood analyzers. More sensitive and specific tests, such as PCR or sequencing, require access to a sample of the infected tissue, genomic data for all potential pathogens and expensive equipment. Culturing organisms introduces its own biases and is prone to false positives due to contamination. We describe a device for the rapid isolation of neutrophils and measurement of neutrophil elastase activity to provide a measure of host immune activity toward a broad range of infectious agents. CyBIS (Cytocapture of Biomarkers In Situ) is a Point-of-Care (POC) device that isolates neutrophils from a small volume of blood (75 ul) using anti-CD66b antibody-coated paramagnetic beads and analyzes elastase activity via a kinetic assay. This inexpensive and rapid (35 min) testing system provides a quantitative measure that combines neutrophil count with neutrophil elastase activity per cell to diagnose elevated host immune activity and possible infection. Neutrophil-associated elastase is elevated in emergency department patients with clinically relevant infections, including sepsis, compared to healthy control patients.