Cardiac troponin I (cTnI) and cardiac troponin T (cTnT) are challenging analytes to measure quantitatively due to the complex biochemical properties of human cardiac troponins (cTn) and the presence of various forms in the blood of myocardial infarction patients. Factors such as phosphorylation, proteolytic degradation, and the blocking of epitopes by autoantibodies contribute to these challenges. Additionally, as early as 1999, HyTest scientists ( Katrukha, AG et al. ) suggested that certain anti-cTnI monoclonal antibodies (MAbs) are sensitive to the presence of heparin in samples, which could result in a lower response in heparin-containing samples. Our scientists have continued to work on this topic, and recently, a new article titled 'Interaction of Heparin with Human Cardiac Troponin Complex and Its Influence on the Immunodetection of Troponins in Human Blood Samples' was published on May 14th in Clinical Chemistry and Laboratory Medicine (CCLM). 

In this latest article, the authors further discuss the effects of heparin on the measurement of cardiac isoforms of cTnI and cTnT. They propose that heparin binds to free cTnT and interacts with the ITC complex via the cTnT molecule. It was demonstrated that heparin binds to both the human cardiac full-size ternary troponin complex (ITC-complex) and free cTnT, increasing their apparent molecular weights in gel filtration (GF) studies. However, heparin did not bind to the low molecular weight ITC-complex or the binary cTnI-troponin С complex. The identification of heparin binding sites on the cTnT molecule is also highlighted as an important factor to consider when selecting antibodies for the development of new cTnT assays. 

Hytest has systematically characterized cTn and developed comprehensive antibody selection strategies for cTnI and cTnT assay development since 1999. For more detailed information, please check troponin booklet