An Immunoluminometric Assay for Cardiotrophin-1: A Newly Identified Cytokine Is Present in Normal Human Plasma and Is Increased in Heart Failure

Cardiotrophin-1, a member of the interleukin-6 related cytokine family which acts via the glycoprotein 130 signalling pathway, may be involved in the process of ventricular remodelling. Its presence in human plasma has never been reported. We have devised a non-radioactive immunoluminometric sensitive and specific assay for CT-1 based on a competitive ligand binding principle. The chemiluminescent label 4-(2-succinimidyl-oxycarbonylethyl)phenyl-10-methylacridinium 9-carboxylate fluorosulfonate was used to label a peptide representing a domain in the middle section of CT-1. Assay of this domain of CT-1 (amino acids 105–120) in patients with heart failure revealed elevated CT-1 values median 87 [range 74.3–182.8] fmol/ml) compared to normal controls (CT-1 median 29.55 [range 6.9–48.3] fmol/ml, P