Preparation of platelet analogs
Erythrocytes from a vertebrate animal other than a human that have been size reduced and treated with a fixing agent by conventional methods to resemble human platelets are further treated to achieve a size distribution that is detected in a consistent manner by different methodologies of blood cell counting. The further treatment includes heating to a denaturing temperature followed by a second treatment with a fixing agent. The resulting cells are useful as controls for calibrating and checking the accuracy of automated blood cell counting equipment.
1. A process for the manufacture of human platelet analogs for use as reference controls in automated blood cell analyzers, said process comprising:
(a) treating a single lot of red blood cells of a vertebrate other than a human that have been reduced in size by extraction of cellular fluid and fixed with a fixing agent, by heating said cells in the absence of a fixing agent for about 4 hours to about 48 hours to a sufficient degree to achieve a denaturing effect, and
(b) reacting said single lot of cells with a fixing agent after said heating, to cause said single lot to display by optical measurement a log normal size distribution simulating that of human platelets.
2. The process of claim 1 wherein said red blood cells are goat red blood cells.
3. The process of claim 1 wherein said heating of step (a) is performed at about 50° C. to about 75° C. and from about 4 hours to about 24 hours.
4. The process of claim 1 wherein said heating of step (a) is performed at about 50° C. to about 60° C.
5. The process of claim 1 wherein step (b) is performed at a temperature below 30° C. for at least about 2 hours.
6. The process of claim 1 wherein (b) is performed at ambient temperature for 8 to 48 hours.
7. The process of claim 1 wherein (b) is performed at ambient temperature for 16 to 24 hours.
8. The process of claim 1 wherein said fixing agent of step (a) is a crosslinking fixing agent.
9. The process of claim 1 wherein said fixing agent of step (a) is a member selected from the group consisting of glutaraldehyde, formaldehyde, osmium tetroxide, acrolein, and tannic acid.
10. The process of claim 1 wherein said fixing agent of step (a) is a member selected from the group consisting of glutaraldehyde and formaldehyde.
11. The process of claim 1 wherein said fixing agent of step (a) is glutaraldehyde.
12. The process of claim 1 wherein said red blood cells of step (a) prior to heating have a mean platelet volume of from about 7 to about 15 femtoliters.
13. The process of claim 1 wherein said red blood cells of step (a) prior to heating have a mean platelet volume of from about 9 to about 15 femtoliters.
14. The process of claim 1 wherein said red blood cells of step (a) prior to heating have a mean platelet volume of from about 10 to about 13 femtoliters.
15. Modified blood cells for use as analogs of human platelets in reference controls for automated blood cell analyzers, prepared by a process comprising:
(a) treating a single lot of red blood cells of a vertebrate other than a human that have been reduced in size by extraction of cellular fluid and fixed with a fixing agent, by heating said cells to a denaturing temperature in the absence of a fixing agent for about 4 hours to about 48 hours to achieve a denaturing effect, and
(b) reacting said cells with a fixing agent after said heating, to cause said single lot of red blood cells to display by optical measurement a log normal size distribution simulating that of human platelets.
16. The modified blood cells of claim 15 wherein said red blood cells are goat red blood cells.
17. The modified blood cells of claim 15 wherein said denaturing temperature is from about 50° C. to about 75° C. and said heating is performed for a period of from about 4 hours to about 24 hours.
18. The modified blood cells of claim 15 wherein said denaturing temperature is from about 50° C. to about 60° C.
19. The modified blood cells of claim 15 wherein step (b) is performed at a temperature below 30° C. for at least about 2 hours.
20. The modified blood cells of claim 15 wherein step (b) is performed at ambient temperature for 8 to 48 hours.
21. The modified blood cells of claim 15 wherein step (b) is performed at ambient temperature for 16 to 24 hours.
22. The modified blood cells of claim 15 wherein said fixing agent of step (a) is a crosslinking fixing agent.
23. The modified blood cells of claim 15 wherein said fixing agent of step (a) is a member selected from the group consisting of glutaraldehyde, formaldehyde, osmium tetroxide, and tannic acid.
24. The modified blood cells of claim 15 wherein said fixing agent of step (a) is a member selected from the group consisting of glutaraldehyde and formaldehyde.
25. The modified blood cells of claim 15 wherein said fixing agent of step (a) is glutaraldehyde.
26. The modified blood cells of claim 15 wherein said red blood cells of step (a) prior to heating have a mean platelet volume of from about 7 to about 15 femtoliters.
27. The modified blood cells of claim 15 wherein said red blood cells of step (a) prior to heating have a mean platelet volume of from about 9 to about 15 femtoliters.
28. The modified blood cells of claim 15 wherein said red blood cells of step (a) prior to heating have a mean platelet volume of from about 10 to about 13 femtoliters.