Full-Size Cardiac Troponin I and Its Proteolytic Fragments in Blood of Patients with Acute Myocardial Infarction: Antibody Selection for Assay Development

Cardiac troponins are recognized as the primary biomarkers used in the diagnosis of acute myocardial infarction.  These are commonly detected by immunoassays, which offer the wide availability and rapid results needed in clinical care scenarios to rule out myocardial infarction.  However, immunodetection methods can be limited when there is degradation of the target analyte, as is the case with cardiac troponin I. Early studies suggested that the central region, located between amino acid residues 30 and 110, was the most stable part of the molecule.  This was a driver for the majority of current diagnostic systems to utilize antibodies with epitopes located within the central region.  A down side to this approach is that auto antibodies also bind to this region, potentially causing interference and erroneous results. As more recent studies have identified additional cardiac troponin I proteolytic fragments, it is important to understand their composition and prevalence in the blood of patients with acute myocardial infarction.  Furthermore, there is a need to evaluate whether monoclonal antibodies specific to the regions beyond the central section of the molecule can be used to develop cardiac troponin I assays with improved performance over those currently available.  An original article appearing in the July 2018 issue of Clinical Chemistry describes a study investigating these concepts.