Plasma concentrations of growth arrest specific protein 6 and the soluble form of its tyrosine kinase receptor Axl as markers of large abdominal aortic aneurysms

Objective: The tyrosine kinase receptor Axl is expressed in the vasculature and Gas6 is the ligand. The extracellular part of Axl (sAxl) can be found in circulation. The aim of this study was to determine plasma concentrations of Gas6 and sAxl in patients with abdominal aortic aneurysms (AAA) and to evaluate if Gas6 and sAxl can be used as biomarkers. Design and methods: Immunoassays for sAxl and Gas6 were used to investigate plasma from AAA patients. Patients with large (n = 123) or small AAA (n = 122) were compared with healthy controls (n = 141). Results: Gas6 correlated positively and sAxl correlated negatively with AAA size. As a consequence, the calculated Gas6/sAxl ratios correlated even better to AAA size. Forty percent of all patients with a large AAA had higher Gas6/sAxl ratio than any in the control group. Discussion: The Gas6/Axl system might be involved in AAA pathogenesis, and the Gas6/sAxl ratio may be useful as a biomarker. (c) 2009 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.