Chemistry: analytical and immunological testing – Composition for standardization – calibration – simulation,... – Particle count or volume standard or control
Reexamination Certificate
2001-12-03
2003-11-25
Wallenhorst, Maureen M. (Department: 1743)
Chemistry: analytical and immunological testing
Composition for standardization, calibration, simulation,...
Particle count or volume standard or control
C436S008000, C436S063000, C436S164000, C422S073000, C422S082050, C435S002000
Reexamination Certificate
active
06653137
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to an improved method of making a hematology control composition, improved compositions, and their use in an automated or semi-automated hematology analyzer.
BACKGROUND
The proliferation of semi-automated and automated hematology instruments in recent years and the increased regulation of clinical laboratories has placed an increasing demand for high performance, long-term stable reference controls. Certain instruments characterize a sample of blood by detecting the impedance or light scatter or radiofrequency characteristics of cells in a sample. It has become especially popular to use these instruments for differentiating cells relative to each other, as well as for other flow cytometry techniques.
In both U.S. Pat. Nos. 6,187,590 and 5,858,790 (both incorporated by reference) the patentee identifies examples of certain of these instruments, including the ABBOTT CELL-DYN® 4000 Analyzer and the STKS® Analyzer from Beckman Coulter. In the latter patents, differences in the modes of detection of the respective instruments are emphasized as determinative of whether a particular control may properly function in the instrument. The differences are emphasized with particular reference to a control including a nucleated red blood cell component prepared from mammalian nucleated blood cells or avian or fish erythrocytes. The control disclosed is intended specifically for use in a multi-angle light scatter hematology analyzer, such as a CELL DYN® Analyzers. The nucleated red blood cell component is made by stripping a membrane from a nucleated cell.
It would be particularly attractive to provide a control including a simulated nucleated red blood cell component, wherein after preparation the nucleus remains at least partially, if not substantially wholly encapsulated with a membrane, and especially the natural membrane of the cell; thus also rendering the control sensitive to components of the instrument system (e.g., lysing agent, stain or dye, or the like). It would also be attractive to have a simulated nucleated red blood cell component that is useful in a control for any or all of instruments that measure hematological parameters by (for instance) light scatter, radiofrequency or electrical impedance.
SUMMARY OF THE INVENTION
The present invention meets the above needs by providing an improved control composition, and method of making and using the same.
In a particularly preferred embodiment a blood cell is provided for simulating a nucleated red blood cell. When provided, the blood cell has a nucleus and cytoplasm enclosed by a membrane. Cytoplasm is optionally removed from within the membrane and the membrane is handled for preserving it substantially intact at least partially encapsulating the nucleus. The resulting cell form is suspended in a suitable suspension medium and is capable of functioning as a simulated nucleated red blood cell.
In another embodiment, the resulting cell form is incorporated into a multi-parameter hematology control, and particularly one that includes a white blood cell component, prepared from red or white blood cells, adapted for simulating at least three, and more preferably five subpopulations of white blood cells.
In another embodiment, the white blood cell component is prepared from a sample of human whole blood in which white blood cells are fixed prior to lysing of the red blood cells from the whole blood. After red blood cell lysis, the white blood cells are again fixed for a period of at least about 1 hour, and more preferably about 4 to about 5 hours.
In another embodiment, compositions in accordance with the above are employed in a hematology analyzer as a reference control that detects blood cell characteristics on the basis of light scatter, electrical impedance, radiofrequency or a mixture thereof.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
Blood Cell Source
One object of the present invention, as gathered from the foregoing, is to provide a component for a hematology reference control that simulates nucleated red blood cells of human blood. In this regard, the simulation does not necessarily mean that cells be chemically similar to the intended corresponding human cells. Rather, the desired simulation is in a characteristic that would be detected by an instrument suitable for analysis of such cells. For example, by way of summary, an instrument might detect the presence or amount of a particular cell by measuring one or more of light scatter, impedence, radiofrequency response or some other physical response or lack thereof to an applied stimulus.
Thus, as is well known in the art pertaining to blood cell analogs, as exemplified in a number of teachings spanning the past few decades, such as (without limitation) U.S. Pat. Nos. 3,574,137; 3,640,896; 3,873,467; 4,219,440; 4,704,364; 5,207,208; 5,262,327; 5,320,964; 5,389,664; 5,994,139; 6,187,590; 6,187,590 or the like (all of which are expressly incorporated by reference), the simulated blood cell component need not originate from a human blood cell. In fact, though human blood cells may be suitably employed in the present invention for any of the particular components, a preferred component for simulating a blood cell will be one that is derived from a blood cell other than a human blood cell.
In the context of one aspect of the present invention, by way of illustration, and though not intended as limiting, examples of sources of a cell component for simulating a human nucleated red blood cell include reptile nucleated blood cells, avian nucleated blood cells, fish nucleated blood cells or the like. Other mammalian blood cells may be employed as well, such as bovine cells, porcine cells, goat cells or otherwise. In a particularly preferred embodiment, the reptilian source of a nucleated blood cell is an alligator, the fish source is a salmon and the avian source is a turkey or chicken. Most preferably, the source of blood cell is an alligator, a salmon or a mixture thereof. It should be appreciated from the above that the source of the cell component for simulating a human nucleated red blood cell need not be a red blood cell, but may indeed be a nucleated white blood cell or other cell.
Starting materials for providing these components are widely available and preferably they are provided in a suitable suspension. For example, the starting material for a cell for simulating a human nucleated red blood cell may be suitably supplied in whole blood form or in a suspension form or otherwise in a suitable handling medium, (e.g., without limitation, a liquid or gel medium). Such medium preferably includes a suitable amount of an anti-coagulant, and may include other ingredients for stabilizing the cells during storage, transport and handling.
Early Stage Cell Preparation
For preparing nucleated red blood cells in accordance with the present invention, upon providing cells from a suitable source, the cells are treated as desired for removing any of the handling medium and for subsequent processing for forming a simulated human nucleated red blood cell. In one preferred embodiment, this can be accomplished by simply washing the cells with a suitable solution, preferably a buffered solution and still more preferably an isotonic wash solution, such as that described (without limitation) in further detail herein, under the heading “Isotonic Wash Solution”.
This treatment step may be done below, at or above room temperature, but preferably under conditions for substantially maintaining the integrity of the nucleus of the cell and a major portion of the cell membrane.
Lysis of Nucleated Blood Cell
In one particularly preferred embodiment of the present invention, though not in every embodiment, lysis is performed upon the nucleated blood cell for permitting cytoplasm from within the cell membrane to escape through the membrane. It is preferred, in these instances, that the membrane remain at least partially surrounding the remaining nucleus. Lysis therefore preferably is a controlled lysis by which the membrane is permeated or otherwise penetra
Howrey Simon Arnold & White , LLP
Streck Laboratories Inc.
Wallenhorst Maureen M.
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