Cellular controls for glycated hemoglobin Hb A1c

• US 20060228803A1
• Filed: 04/08/2005
• Published: 10/12/2006
• Est. Priority Date: 04/08/2005
• Status: Active Grant

• Current Assignee: Streck
• Original Assignee: Streck Laboratories Inc.
• Inventors: Wu, Jiong, Ryan, Wayne L.
• Granted Patent: US 7,361,513 B2
• Time in Patent Office: Days
• US Class Current: 436/67
• CPC Class Codes: G01N 33/723 Glycosylated haemoglobin
• 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 436/105831 Protein or peptide standard or control [e.g., hemoglobin, etc.]
• CPC Class Codes: Y10T 436/108331 Preservative, buffer, anticoagulant or diluent
• CPC Class Codes: Y10T 436/25 including sample preparation
• CPC Class Codes: Y10T 436/25125 Digestion or removing interfering materials

Abstract

Disclosed are cellular hemoglobin Alc (Hb Alc ) normal and abnormal (high) controls for use in detecting Hb Alc levels. The present invention also relates to methods for generating cellular Hb Alc controls using red blood cells and methods for using the cellular controls. The present invention encompasses several methods for the preparation of Hb Alc cellular controls including: (1) a boronate method where the glycation occurs non-specifically; (2) a stabilized diabetic blood method where the glycation occurs specifically on Hb Alc, and (3) the glycation of normal blood method that is achieved by controlling conditions such that glycation occurs predominantly on Hb Alc. These methods produce cellular Hb Alc controls with desirable stability and that can be detected on a variety of instruments.

Claims

1. A method for preparing a cellular hemoglobin Alc (Hb Alc) control comprising the steps of:

(a) selecting a sample of red blood cells with at least one desired feature from a suitable subject;

(b) washing the sample;

(c) processing the washed sample to remove white blood cells;

(d) preserving the Hb Alc molecules in said sample;

(e) washing the sample of step (d);

(f) optionally adjusting the Hb Alc level to a desired level thereby producing a cellular Hb Alc control, wherein the level of Hb Alc of the control is substantially stabilized and detectable.

2. The method of claim 1, further comprising the step:

g) admixing the control of step f) in a suspension medium suitable for delivering said control to a suitable analytical instrument for analysis.

3. The method of claim 1, wherein said suitable subject is a mammal, an avian, or a reptile subject.

4. The method of claim 3, wherein said sample is obtained from human, bovine, or both human and bovine subjects.

5. The method of claim 3, wherein said sample is obtained from a diabetic subject.

6. The method of claim 1, wherein Hb Alc level of the control is detectable using immunologic detection, ion exchange, or affinity chromatography.

7. The method of claim 1, wherein the Hb Alc level of the control is at least about 1-5%.

8. The method of claim 1, wherein the Hb Alc level of the control is greater than 5%.

9. The method of claim 1, wherein the Hb Alc level of the control is between about 5-20%.

10. The method of claim 1, wherein the step of preserving comprises treating the cells with about 0.001-3% polyethylene glycol.

11. The method of claim 10, wherein the step of preserving comprises treating the cells with about 0.001-1% glucose.

12. The method of claim 1, wherein the preserving step comprises fixing the red blood cells.

13. The method of claim 12, wherein fixing comprises treating the cells with about 0.002-0.10% glutaraldehyde.

14. The method of claim 1, wherein adjusting the level of Hb Alc comprises maintaining pH at from about 6-8.

15. The method of claim 1, further comprising after step (c), incubating the red blood cells with about 3% glucose and about 0.5% NaCNBH₃ at room temperature.

16. The method of claim 1, further comprising after step (c) a step of incubating the red blood cells for at least about 50 days, at about 4-6°

C., with a glycation solution which comprises;

0.04% Methyl paraben;

0.3% PEG 20K;

0.025% Inosine;

0.015% Chloramphenicol

0.04% Neomycin Sulfate

0.585% EDTA (2Na⁺);

325% Magnesium gluconate;

225% Na₂HPO₄;

0.07% NaOH;

0.005% NaF; and

3.15% Glucose;

wherein the osmolality of the glycation solution is adjusted to about 300±

7 (mOsm) and pH is adjusted to about 7.0±

0.1.

18. The control of claim 17, prepared by the method of claim 1.

17. A cellular hematology control for Hb Alc comprising red blood cells having a desired level of Hb Alc and wherein the Hb Alc level is substantially stabilized.

19. The control of claim 17, wherein the red blood cells have a substantially stable Hb Alc content for at least about one month.

20. The control of claim 17, wherein the red blood cells have a substantially stable Hb Alc content for at least about three months.

21. The control of claim 17, wherein the Hb Alc level is at least about 1-5%.

22. The control of claim 17, wherein the Hb Alc level is greater than 5%.

23. The control of claim 17, wherein the Hb Alc level is between about 5-20%.

24. The control of claim 17, wherein the desired level of Hb Alc is stabilized through adjusting pH of the control to from about 6-8.

25. The control of claim 17, wherein the desired level of Hb Alc is stabilized through the addition of glucose at an amount of from about 0.001-1%.

26. A method for determining the accuracy of an analytical instrument capable of measuring Hb Alc levels comprising the steps of:

a. providing the cellular hematology control for Hb Alc of claim 17 in a known reference quantity;

b. determining the Hb Alc level in said control of step a with said instrument; and

c. comparing the Hb Alc level obtained in step b with said known reference quantity;

wherein said comparing indicates the accuracy of said analytical instrument.