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

Abstract

In addition to mAbs specific to the central part of cTnI (approximately aar 34-126), antibodies specific to the adjacent epitopes (approximately aar 23-36 and 126-196) could be used in assays because they recognize ≥80% of cTnI in patients' blood samples within the first 36 h after AMI.

Two desired epitopes of cTnI benefit for preparation of standardized monoclonal antibodies

“…19 Another study showed that the N-terminal and C-terminal portions of cTnI (approximately amino acid 1-30 and 110-210) are easy to degrade. 13 Therefore, the most stable part of cTnI are amino acid residues 30 to 50 and 80 to 90. 13 Therefore, the most stable part of cTnI are amino acid residues 30 to 50 and 80 to 90.…”

“…15 Most of the antibodies recognize the amino acid residues 50-80 and 90-130 regions of the free cTnI can hardly recognize TnI-TnC binary and TnT-TnI-TnC ternary complex. In an immunoassay, the utilization of mAbs that are recognized to the degradative region of the analyte might lead to distinct underestimation of the biomarkers' concentration in the sample, and misdiagnosis may occur in some patients or patient groups, 13 which show that only a few epitopes located on the most stable part of cTnI could be used as an epitope for antibody development. In an immunoassay, the utilization of mAbs that are recognized to the degradative region of the analyte might lead to distinct underestimation of the biomarkers' concentration in the sample, and misdiagnosis may occur in some patients or patient groups, 13 which show that only a few epitopes located on the most stable part of cTnI could be used as an epitope for antibody development.…”

“…13 Therefore, the most stable part of cTnI are amino acid residues 30 to 50 and 80 to 90. 13 Therefore, it is more reasonable to select standard epitopes that is located on the most stable part of cTnI to manufacture standard antibodies rather than to use the whole protein. 13 Therefore, it is more reasonable to select standard epitopes that is located on the most stable part of cTnI to manufacture standard antibodies rather than to use the whole protein.…”

“…Ultimately the mAbs 2C3 and 7D2 were selected. 13 In order to verify mAbs 7D2 and 2C3 whether can recognize with different forms of cardiac troponin I. the 7D2 and 2C3 were used to detect with phosphorylated and proteolytic forms,TnI-TnC binary and TnT-TnI-TnC ternary complex. We identified the isotype of all the mAbs as IgG1.…”

“…12 Most of the antibodies recognize the amino acid residues 50 to 80 and 90 to 130 regions of the free cTnI can hardly recognize TnI-TnC binary and TnT-TnI-TnC ternary complex. 13 In order to verify mAbs 7D2 and 2C3 whether can recognize with different forms of cardiac troponin I. the 7D2 and 2C3 were used to detect with phosphorylated and proteolytic forms,TnI-TnC binary and TnT-TnI-TnC ternary complex. As can be seen in Figure 5, mAbs 7D2 and 2C3 can bind to these various modified forms and complexes of cTnI.…”