ASSAY FOR CARDIAC TROPONIN AUTOANTIBODIES

• US 20100311079A1
• Filed: 08/17/2010
• Published: 12/09/2010
• Est. Priority Date: 10/26/2006
• Status: Active Grant

• Current Assignee: Abbott Laboratories Incorporated
• Original Assignee: Abbott Laboratories Incorporated
• Inventors: Doss, Robert C., Adamczyk, Maciej, Mattingly, Phillip G., Brashear, Roy Jeffrey
• Granted Patent: US 8,173,382 B2
• Time in Patent Office: Days
• US Class Current: 435/7.1
• CPC Class Codes: G01N 2800/324 Coronary artery diseases, e.g. angina pectoris, myocardial infarction
• CPC Class Codes: G01N 2800/325 Heart failure or cardiac arrest, e.g. cardiomyopathy, congestive heart failure
• CPC Class Codes: G01N 33/54326 Magnetic particles
• CPC Class Codes: G01N 33/564 for pre-existing immune complex or autoimmune disease , i.e. systemic lupus erythematosus, rheumatoid arthritis, multiple sclerosis, rheumatoid factors or complement components C1-C9
• CPC Class Codes: G01N 33/6854 Immunoglobulins
• CPC Class Codes: Y10T 436/10 Composition for standardization, calibration, simulation, stabilization, preparation or preservation; processes of use in preparation for chemical testing
• CPC Class Codes: Y10T 436/101666 Particle count or volume standard or control [e.g., platelet count standards, etc.]
• CPC Class Codes: Y10T 436/25125 Digestion or removing interfering materials

Abstract

The invention provides among other things methods and kits based on assaying for cardiac troponin autoantibodies, either in conjunction with an assay for cardiac troponin and/or as an independent indicator of cardiac pathology, such as myocarditis, cardiomyopathy, and/or ischemic heart disease. Assay methods of the invention can be employed among other things to identify cardiac pathology, or risk thereof, in subjects who have an autoimmune disease or who are related to an individual with an autoimmune disease. In particular embodiments, the invention also provides a method of determining whether a subject having, or at risk for, a cardiac pathology is a candidate for immunosuppressive therapy or immunoabsorption therapy. The invention also provides kits and kit components that are useful for performing the methods of the invention.

Claims

1. A method of determining the reliability of a cardiac troponin antigen assay in a biological sample from a subject, the method comprising

assaying the biological sample from the subject for an autoantibody reactive with the cardiac troponin antigen being assayed, to allow detection of an elevated level of the cardiac troponin-reactive autoantibody against the cardiac troponin antigen in the biological sample in comparison to a predetermined normal control sample having normal values of cardiac troponin-reactive autoantibody against the cardiac troponin antigen, wherein assaying comprises detecting the level of cardiac troponin-reactive autoantibody, and:

detecting an elevated level of cardiac troponin-reactive autoantibody in the biological sample in comparison to the predetermined normal control sample provides indication that the biological sample is scored as one in which the cardiac troponin antigen assay is not reliable, and

detecting a level of cardiac troponin-reactive autoantibody that is not elevated in the biological sample in comparison to the predetermined normal control sample provides indication that the biological sample is scored as one in which the cardiac troponin antigen assay is reliable.

2. The method of claim 1, wherein the biological sample is obtained from a human.

3. The method of claim 1, wherein the cardiac troponin antigen assayed comprises a cardiac troponin antigen selected from the group consisting of a cardiac troponin I, cardiac troponin T, and cardiac troponin C, and complexes thereof.

4. The method of claim 1, wherein the autoantibody is reactive with a cardiac troponin antigen comprising a cardiac troponin antigen selected from the group consisting of a cardiac troponin I, cardiac troponin T, and cardiac troponin C, and complexes thereof.

5. The method of claim 1, said method comprising:

(a) contacting the biological sample with a cardiac troponin antigen affixed to a solid phase, under conditions sufficient for binding of the cardiac troponin antigen to any corresponding cardiac troponin-reactive autoantibody present in the sample; and

(b) measuring agglutination resulting from binding of the cardiac troponin antigen affixed to the solid with any corresponding cardiac troponin-reactive autoantibody present in the sample,

wherein the degree of agglutination is positively correlated with the concentration of the corresponding cardiac troponin-reactive autoantibody present in the sample.

6. The method of claim 1, said method comprising:

(a) contacting the biological sample with a cardiac troponin antigen, under conditions sufficient for binding of the cardiac troponin antigen to any corresponding cardiac troponin-reactive autoantibody present in the sample; and

(b) detecting the level of complex(es) comprising the cardiac troponin antigen bound to cardiac troponin-reactive autoantibody.

7. The method of claim 6, wherein the level of said complex(es) is positively correlated with the concentration of the corresponding cardiac troponin-reactive autoantibody present in the sample.

8. The method of claim 7, said method additionally comprising:

(c) contacting the biological sample with a species-specific antibody which binds to the cardiac troponin-reactive autoantibody against the cardiac troponin antigen, wherein the species-specific antibody is specific for the species from which the biological sample was obtained, under conditions sufficient for specific binding of the species-specific antibody to the corresponding cardiac troponin-reactive autoantibody present,

wherein said detecting comprises detecting any complex comprising the cardiac troponin antigen bound to the corresponding cardiac troponin-reactive autoantibody, which is bound to species-specific antibody.

9. The method of claim 8, wherein the contacting of claim 6(a) and the contacting of claim 8(c) are carried out simultaneously.

10. The method of claim 8, wherein the contacting of claim 12(a) and the contacting of claim 8(c) are carried out sequentially, in any order.

11. The method of claim 8, wherein the cardiac troponin antigen is affixed to a solid phase.

12. The method of claim 11, wherein the solid phase comprises a microplate.

13. The method of claim 11, wherein the solid phase comprises a microparticle.

14. The method of claim 13, wherein the microparticle is magnetic or paramagnetic.

15. The method of claim 11, wherein the solid phase comprises an electrode.

16. The method of claim 8, wherein the species-specific antibody is labeled.

17. The method of claim 16, wherein the label comprises a direct label.

18. The method of claim 17, wherein the direct label comprises an acridinium-9-carboxamide.

19. The method of claim 16, wherein the label comprises an indirect label.

20. The method of claim 16, wherein the detecting of claim 14(c) comprises contacting the label with an indicator reagent.

21. The method of claim 8, wherein the species-specific antibody is affixed to a solid phase, binding of the species-specific antibody to the corresponding cardiac troponin-reactive autoantibody present in the sample forms a solid phase-affixed complex, and said detecting comprises detecting the level of the solid phase-affixed complex.

22. The method of claim 21, wherein the solid phase comprises a microplate.

23. The method of claim 21, wherein the solid phase comprises a microparticle.

24. The method of claim 23, wherein the microparticle is magnetic or paramagnetic.

25. The method of claim 21, wherein the solid phase comprises an electrode.

26. The method of claim 8, wherein the cardiac troponin antigen is labeled.

27. The method of claim 26, wherein the label comprises a direct label.

28. The method of claim 27, wherein the direct label comprises an acridinium-9-carboxamide.

29. The method of claim 26, wherein the label comprises an indirect label.

30. The method of claim 26, wherein the detecting of claim 14(c) comprises contacting the label with an indicator reagent.

31. The method of claim 1, wherein the method is carried out before, or simultaneously with, the cardiac troponin antigen assay.

32. The method of claim 1, wherein the method is carried out in the absence of the cardiac troponin antigen assay.

33. The method of claim 1, wherein the sample is determined to have an elevated level of cardiac troponin-reactive autoantibody, and the sample is assessed for one or more additional indicators of cardiac pathology selected from the group consisting of myoglobin, CK-MB, BNP, CRP, Troponin-I, Troponin-T, blood oxygen level, cardiac imaging, and electrocardiography.

34. The method of claim 6, wherein the signal is negatively correlated with the concentration of the corresponding cardiac troponin-reactive autoantibody present in the sample.

35. The method of claim 34, said method additionally comprising:

(c) contacting the biological sample with a labeled cardiac troponin-reactive antibody under conditions sufficient for specific binding of the labeled cardiac troponin-reactive antibody to the cardiac troponin antigen.

36. The method of claim 35, wherein the contacting of claim 6(a) and the contacting of claim 35(c) are carried out simultaneously.

37. The method of claim 35, wherein the contacting of claim 6(a) and the contacting of claim 35(c) are carried out sequentially, in any order.

38. The method of claim 35, wherein the cardiac troponin antigen is affixed to a solid phase, binding of the cardiac troponin antigen to labeled cardiac troponin-reactive antibody or to the corresponding cardiac troponin-reactive autoantibody present in the sample forms a solid phase-affixed complex, and said detecting comprises detecting a signal from the solid phase-affixed complex.

39. The method of claim 38, wherein the solid phase comprises a microparticle.

40. The method of claim 38, wherein the solid phase comprises an electrode.

41. The method of claim 35, wherein the label comprises a direct label.

42. The method of claim 41, wherein the direct label comprises an acridinium-9-carboxamide.

43. The method of claim 35, wherein the label comprises an indirect label.

44. The method of claim 35, wherein the detecting of (c) comprises contacting the label with an indicator reagent.

45. A test kit for use in the method of claim 33, the test kit comprising a humanized monoclonal antibody, wherein the humanized monoclonal antibody is specific for a cardiac Troponin-I or Troponin-T.

46. The test kit of claim 45, wherein the test kit additionally comprises a solid phase and a capture agent affixed to the solid phase, wherein the capture agent is selected from the group consisting of a cardiac troponin antigen and a species-specific antibody which binds to the cardiac troponin-reactive autoantibody against the cardiac troponin antigen, wherein the species-specific antibody is specific for the species from which the biological sample is to be obtained.

47. The test kit of claim 46, wherein the test kit additionally comprises a labeled detection agent, wherein

if the capture agent comprises a cardiac troponin antigen, the detection agent comprises a species-specific antibody;

and

if the capture agent comprises a species-specific antibody, the detection agent comprises a cardiac troponin antigen.

48. The test kit of claim 45, wherein the test kit additionally comprises a labeled non-human monoclonal antibody, wherein the non-human monoclonal antibody is specific for a cardiac Troponin-I or Troponin-T.

49. The test kit of claim 47, wherein the species-specific antibody comprises a human-specific antibody.

50. The test kit of claim 47, wherein at least the label comprises a direct label.

51. The test kit of claim 50, wherein the direct label comprises an acridinium-9-carboxamide.

52. The test kit of claim 47, wherein the label comprises an indirect label.

53. The test kit of claim 47, additionally comprising an indicator reagent that interacts with at least one label to produce a detectable signal.

54. The test kit of claim 46, wherein the solid phase comprises a microplate.

55. The test kit of claim 46, wherein the solid phase comprises a microparticle.

56. The test kit of claim 46, wherein the solid phase comprises an electrode.