Development of an immunoassay for the derived-peptide of chromogranin A, Vasostatin-I (1-76): assessment of severity in patients with sepsis.

Context: Proteolytic fragments of chromogranin A (CgA) including the CgA 1-76 fragment (called vasostatin-I [VS-I]) could be a useful biomarker of sepsis, but there is no available immunoassay. Methods: A sandwich ELISA for VS-I was developed, and plasma VS-I was measured in 30 healthy controls and 60 critically ill patients with sepsis. Results: The ELISA showed intra- and inter-assay coefficients of variations (CVs) below 4 and 9%. Plasma VS-I was significantly increased compared with controls in patients with sepsis, severe sepsis, and sepsis shock (p < 0.0001). Receiver operating curve (ROC) analyses indicated that plasma VS-I was more sensitive and specific than plasma CgA to diagnose sepsis and to assess its severity. Conclusions: The measurements of plasma VS-I with this new ELISA may be useful for the clinical investigation of patients with sepsis.