Development of monoclonal antibodies for an assay of cardiac troponin-I and preliminary results in suspected cases of myocardial infarction.
To improve the specificity of biochemical markers of myocardial infarction (MI), we have developed a double monoclonal "sandwich" enzyme immunoassay to measure cardiac troponin-I (cTnI) in serum. We produced eight IgG monoclonal antibodies against human cardiac troponin-I (cTnI) and tested them against human and animal (canine, bovine, and rabbit) troponins. Five antibodies were cardiac-specific; none of the antibodies were species-specific. Two of the five cTnI-specific monoclonal antibodies were utilized in an immunoassay. Standards were made by adding purified human cTnI to affinity-stripped cTnI-free human sera to cover the range 0-100 micrograms/L for cTnI. The dose-response curve was nonlinear but reproducible. Total assay imprecision (CV) varied between 11% and 21%. The upper limit of the reference range (nonparametric 95% interval) was established as 3.1 micrograms/L by measuring cTnI concentration in sera of 159 hospitalized patients without evidence of cardiac disease. Purified human skeletal TnI up to 10,000 micrograms/L did not affect the assay (calculated cross-reactivity < 0.1%). Diagnostic sensitivities of creatine kinase MB isoenzyme (CK-MB) and cTnI were evaluated retrospectively in 49 consecutive patients with proven MI. In the 30 patients for whom sufficient information was available to establish an accurate time course, CK-MB was more sensitive during the first 4 h after the onset of chest pain, but thereafter the sensitivities were similar up to 48 h. However, cTnI is more cardiac-specific than is CK-MB and remains increased longer than does CK-MB.
Bodor
G S
GS
Washington University School of Medicine, Department of Pathology, St. Louis, MO 63110.
Porter
S
S
Landt
Y
Y
Ladenson
J H
JH
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology; D000918:Antibody Specificity; D001667:Binding, Competitive; D002417:Cattle; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay / Q000706:statistics & numerical data; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D007118:Immunoassay / Q000706:statistics & numerical data; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D008969:Molecular Sequence Data; D009203:Myocardial Infarction / Q000097:blood*; D009206:Myocardium / Q000737:chemistry*; D011786:Quality Control; D011817:Rabbits; D012016:Reference Values; D012189:Retrospective Studies; D014336:Troponin / Q000097:blood*; D019210:Troponin I
D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D014336:Troponin; D019210:Troponin I