Patent Description:
Automated blood analyzers are well-established instruments for the measurement of leukocytes, erythrocytes and platelets in whole blood. The leukocyte components of blood differ from erythrocytes and platelets morphologically and functionally. Impedance, light scatter and enzymatic and antigenic differences serve as the basis for counting and differentiating leukocytes by automated hematology. These instruments are highly complex and do not lend themselves to point-of-care (POC) assay development.

Activation of phagocyte metabolism, i.e., the "respiratory burst", is characterized by a large increase in glucose metabolism via the dehydrogenases of the hexose monophosphate shunt (pentose pathway) and a proportional increase in non-mitochondrial O<NUM> consumption (Sbarra and Karnovsky <NUM>). Both activities reflect the activation of NADPH oxidase (NADPH: O<NUM> oxidoreductase), an enzyme common to blood phagocytes (Rossi, Romeo et al. Activation of phagocyte NADPH oxidase drives combustive dioxygenation reactions that yield a native chemiluminescence as an energy product (Allen et al <NUM>). Native leukocyte chemiluminescence is O<NUM>-dependent and directly proportional to hexose monophosphate shunt dehydrogenase activity. NADPH oxidase activation results in the generation of HO<NUM>, O<NUM>- and H<NUM>O<NUM>. The H<NUM>O<NUM> generated serves as substrate for MPO (H<NUM>O<NUM>:halide oxidoreductase) oxidation of chloride to hypochlorite (OCl-), and secondary chemical reaction with an addition H<NUM>O<NUM> yielding singlet molecular oxygen (<NUM>O<NUM>*) (Allen, Yevich et al. <NUM>, Allen <NUM>). The halide-dependent haloperoxidase activity of isolated MPO also yield native chemiluminescence as an energy product (Allen <NUM>, Allen <NUM>).

Chemiluminescence quantum yield, i.e., the ratio of photons emitted per oxygenation event, is dependent on the type and quantity of oxygenating agent generated, and on the nature and quantum efficiency of the substrate oxygenated. Oxygenation of native substrates is associated with a relatively low chemiluminescence quantum yield and this yield varies with the nature of the substrate oxygenated. Introducing a high quantum yield chemiluminigenic substrate (CLS) overcomes the problems of sensitivity and substrate variability. Addition of cyclic hydrazides, e.g., luminol, increase the yield of phagocyte luminescence by greater than a thousand-fold (Allen and Loose <NUM>). Acridinium salts such as lucigenin also greatly increase leukocyte luminescence yield (Allen <NUM>, Allen <NUM>).

Cyclic hydrazide and acridinium chemiluminescence can be chemically elicited by exposure to H<NUM>O<NUM> under alkaline conditions (Albrecht <NUM>, Totter <NUM>). However, these substrates do not yield CL in mildly acidic-to-neutral pH conditions of physiologic milieux. Luminol- and lucigenin-dependent phagocyte CL activities measure different oxygenation pathways (Allen <NUM>, Allen <NUM>). Luminol CL results from dioxygenations generating electronically excited aminophthalate, i.e., luminol + O<NUM> → aminophthalate + N<NUM> + photon. In phagocytic leukocytes, such activity is strongly associated MPO. Luminol CL results from non-reductive, simple dioxygenation. A small luminol CL is observed in MPO-negative leukocytes, but MPO-positive leukocytes yield more than a hundredfold greater luminescence (Allen <NUM>, Merrill, Bretthauer et al. <NUM>, Allen <NUM>).

Phagocyte NADPH oxidase catalyzes the univalent reduction of O<NUM> to HO<NUM>. In neutral milieu, HO<NUM> dissociates yielding O<NUM>- and H+, O<NUM>- and HO<NUM> disproportionate yielding H<NUM>O<NUM>. Under acid to neutral conditions, the divalent cationic lucigenin (N,N'-dimethyl-<NUM>,<NUM>' biacridinium and bis-N-methylacridinium) can undergo one electron reduction yielding the monovalent cation radical, i.e., lucigenin++ + e- → lucigenin+, and this radical can react with O<NUM>- to yield a dioxetane intermediate, and ultimately, two N-methylacridone and a photon, i.e., lucigenin+ + O<NUM>- → lucigenin-O<NUM> → <NUM> N-methylacridone + photon (Allen <NUM>, Allen <NUM>).

The present inventors surprisingly found that complex instrumentation required for impedance and flow cytometric measurements of neutrophils can be obviated by using a chemiluminescence approach to directly measure the functional activity of stimulated neutrophils present in diluted whole blood. The neutrophils per volume of whole blood are determined by measuring stimulated NADPH oxidase-dependent reductive dioxygenation of lucigenin as a chemiluminigenic substrate. Introducing a stimulus, such as PMA, that is optimal for activation of neutrophil NADPH oxidase results in generation of reductive dioxygenating activity.

The resulting reductive dioxygenation of lucigenin yields CL that can be quantified by measuring the light emitted using a luminometer. This luminescence is proportional to the metabolic activity of the neutrophils per volume of whole blood tested. This absolute neutrophil function (ANF) assay is proportional to the absolute neutrophil count (ANC) and is applicable for assessing the clinical state of a patient with regard to inflammation/infection or chemotherapy related bone marrow suppression. Such function-based analysis provides an alternative and arguably superior assay compared to the conventional ANC. The technical requirements of the ANF approach are applicable to point-of-care testing. As described in the Examples herein, the ANF assay allows quantitative assessment of neutrophil number (ANC) and function in blood during the initial sixteen-hour interval post venipuncture.

The present disclosure provides a method for estimating a number of phagocytes in a body fluid of an animal, the method comprising: stimulating NADPH oxidase activity of the phagocytes; and quantifying a resulting reductive dioxygenation of a chemiluminigenic substrate by an emitted chemiluminescence of the chemiluminigenic substrate using an instrument capable of measuring light.

In an embodiment, the NADPH oxidase activity of the phagocytes is stimulated by an immunologic or chemical capable of activating a respiratory burst by the phagocytes.

In an embodiment, the NADPH oxidase activity of the phagocytes is stimulated by a stimulus in solution or coated to a surface contacted by the phagocytes. The stimulus can be phorbol myristate acetate (PMA).

In an embodiment, the animal is a human.

The phagocytes are neutrophil leukocytes.

The chemiluminigenic substrate is lucigenin (N,N'-dimethyl-<NUM>,<NUM>'-biacridinium dinitrate). The lucigenin can be in solution or coated to a surface contacted by the phagocytes.

The method comprises diluting the whole blood <NUM> to <NUM> to diminish erythrocyte absorbance of chemiluminescence.

In an embodiment, the method comprises using a lectin to aggregate or remove erythrocytes from the body fluid to facilitate chemiluminescence detection.

The emitted chemiluminescence is measured by a portable or hand-held luminometer. In an embodiment, the components are prefabricated to facilitate point-of-care testing.

The method further comprises using the estimated number of neutrophils to determine an absolute neutrophil count (ANC) and further comprises using the ANC to assess myelopoietic suppression in the animal, e.g., myelopoietic suppression is associated with chemotherapy or a measure of inflammation or infection. In this regard, inflammation or infection typically increases myelopoietic activity, but neutrophil consumption in response to infection can actually decrease the neutrophil count.

The present disclosure also describes a method for estimating myelopoiesis stimulation is provided. The method comprises: measuring non-reductive dioxygenation-driven myeloperoxidase (luminol CL) activity and reductive dioxygenation (lucigenin CL) activity of chemically-activated blood neutrophils of an animal using an instrument capable of measuring light; and calculating a ratio of the luminol CL activity to the lucigenin CL activity.

The absolute neutrophil function (ANF) assay disclosed herein includes a sensitive chemiluminigenic probe method for determination of the number of functional phagocytes, i.e., neutrophil leukocytes with minor contributions from monocytes and eosinophils, in diluted whole blood. Specifically, phagocyte function is quantified by introducing lucigenin as a chemiluminigenic probe and measuring the chemiluminescence product of stimulated NADPH oxidase reductive dioxygenation activity.

The method requires less than a drop of whole blood. A small volume of the specimen is diluted in a balanced salt solution. The diluted specimen is introduced into a milieu containing a chemical stimulant, such as phorbol <NUM>-myristate <NUM>-acetate (PMA), capable of activating phagocyte NADPH oxidase-dependent respiratory burst metabolism, and a chemiluminigenic probe susceptible to reductive dioxygenation, i.e., lucigenin (N,N'-dimethyl-<NUM>,<NUM>'-biacridinium dinitrate). Such contact activates phagocyte NADPH oxidase-dependent reductive dioxygenation of lucigenin yielding chemiluminescence that can be detected and quantified by luminometry. Chemiluminigenic probes such as luminol measure phagocyte non-reductive (simple) dioxygenation reactions, especially those catalyzed by myeloperoxidase (MPO).

Under normal myelopoietic conditions, measurement of non-reductive dioxygenation approximates the number of neutrophils present. Inflammatory stimulation and g-CSF treatment expand the promyelocytic pool of the bone marrow and can result in a several-fold increase in MPO content per neutrophils. Non-reductive dioxygenation activity reflects MPO content per phagocyte, and reflects the specific MPO content per phagocyte. NADPH oxidase-dependent reductive dioxygenation of lucigenin is not dependent on MPO, and consequently, is directly proportional to the number of functional phagocytes in the specimen. The lucigenin-based ANF system quantifies phagocyte presence by measuring stimulated phagocyte reductive dioxygenation. In the absence of genetic, e.g., chronic granulomatous disease, or an acquired neutrophil abnormality, lucigenin-dependent measurement of NADPH oxidase reductive dioxygenation activity is MPO-independent and closely approximates the neutrophil count of the specimen. The ANC determines the number of neutrophils present in a specimen. The ANF assay provides more clinically relevant information based on quantifying the functional presence of neutrophils in a specimen. The ANF assay is demonstrated to quantitatively reflect the whole blood ANC during the initial sixteen-hour post venipuncture interval, and is applicable to point-of-care testing.

Although NADPH oxidase activity per phagocyte is relatively constant, myeloperoxidase (MPO) activity per phagocyte varies with the state of myelopoietic stimulation. MPO and cationic proteases are lysosomal enzymes synthesized in the promyelocytic phase of development and stored in the azurophilic granules of neutrophils (Bainton <NUM>). The concentration of MPO per phagocyte is dependent on the degree of myelopoietic stimulation, i.e., activation by colony stimulating factors (physiologic or recombinant G-CSF or GM-CSF) and on the number of mitotic divisions during the myelocytic phase of neutrophil development (Allen, Stevens et al. For example, each division in the myelocytic phase dilutes the myeloperoxidase per neutrophil by one half. Components of NADPH oxidase are synthesized in the myelocytic phase of development, and required for respiratory burst metabolism. Consequently, the NADPH oxidase activity per phagocyte is relatively constant with regard to variation in myelopoietic activity. The specific NADPH oxidase activity per phagocyte remains relatively constant in various conditions of inflammation and myelopoietic stimulation or suppression.

As such, stimulated oxidase activity closely approximates the phagocyte count, especially the neutrophil count. Measurement of such activity closely approximates the absolute neutrophil count per volume of blood or body fluid. Introduction of lucigenin as chemiluminigenic probe allows sensitive quantification of phagocyte NADPH oxidase reductive dioxygenation activity (Allen <NUM>, Allen <NUM>, Allen <NUM>). A simple or non-reductive dioxygenation is a reaction where O<NUM> is incorporated in a substrate, e.g., luminol + O<NUM> → aminophthalate + N<NUM> + photon (Allen and Loose <NUM>). A reductive dioxygenation is a reaction where O<NUM> plus two reducing equivalents (<NUM> electrons + <NUM> protons) is incorporated, e.g., lucigenin + <NUM> electrons +<NUM> protons + O<NUM> → <NUM> N-methyl acridone + photon.

NADPH oxidase dependent reductive dioxygenation of lucigenin provides a measurement of absolute neutrophil function (ANF) that closely approximates the absolute neutrophil count (ANC). In addition to providing information consistent with an ANC, lucigenin chemiluminescence (CL) measurement of stimulated neutrophil oxidase activity provides useful clinical information and can be applied to point-of-care (POC) testing using a hand-held luminometer.

Activity-based measurement of neutrophils offers additional information. The ANC quantifies the physical presence of neutrophils, but does not quantify neutrophil function. As such, conditions associated with impaired phagocyte function, e.g., chronic granulomatous disease or any toxic effect of treatment on neutrophil function, are not detected. Functional measurement of the respiratory burst activity that drives reductive dioxygenation activity quantifies neutrophil microbicidal capacity. By analogy, the antigenic detection of an enzyme does not provide information with regard to its function. An enzyme may be antigenically present, but non-functional. Functional measurement of the enzyme provides more complete and clinically useful information; i.e., the enzyme is present and functional.

When stimulated neutrophils are quantified by measuring reductive dioxygenation of lucigenin, the CL response correlates with the neutrophil count. When stimulated neutrophils are quantified by measuring non-reductive dioxygenation of luminol, the CL response shows less correlation with the neutrophil count. Chemiluminigenic probes such as luminol measure non-reductive dioxygenation or dioxygenation activity, especially those catalyzed by MPO (Allen <NUM>). Under normal myelopoietic conditions, the MPO content per neutrophil is stable, and luminol dioxygenation activity roughly approximates the number of neutrophils present. However, in clinical conditions associated with increased myelopoietic activity, e.g., g-CSF treatment and inflammatory stimulation, the promyelocytic pool of the bone marrow is expanded, and there are fewer mitotic divisions in the myelocytic pool of the marrow. MPO is synthesized only during the promyelocytic stage of development. Inflammatory stimulation or therapeutic treatment with G-CSF stimulates and expands the promyelocytic pool and decreases the number of divisions in the myelocytic pool. Consequently, the azurophilic granules containing MPO are not diluted by mitoses in the myelocytic phase of development. Neutrophils synthesized under such stimulated myelopoietic conditions show several-fold increases in MPO per neutrophils (Allen et al <NUM>).

The ANF method disclosed herein is highly sensitive and can be performed on less than a microliter of diluted whole blood. As the following examples demonstrate, the ANF chemiluminigenic technique for quantifying phagocytes in blood or body fluids provides the functional equivalent of an ANC. This lucigenin CL method is technically flexible and is applicable to point-of-care testing (POCT) using a portable or handheld luminometer for measurement. The acceptance and demand for POCT continues to increase (Asha, Chan et al. <NUM>, Schilling <NUM>). No handheld POCT method is available for ANC (POCT).

The following non-limiting examples provide scientific data supporting the concepts disclosed herein.

Human blood specimens tested were provided by a local clinical testing laboratory. De-identified blood specimens were obtained with time of venipuncture, age (in years), sex of the Subject, and the automated hematology analyzer (Advia <NUM>, Siemens AG) printout. The reason for ordering the complete blood count and information on the Subject's medical condition were unknown.

The blood specimens were maintained at ambient temperature (<NUM> ± <NUM> C°) until tested. Each of the <NUM> blood-specimens were tested in triplicate. The average (mean) post-venipuncture age of the blood with standard deviation (SD) at initial testing was <NUM> ± <NUM> hrs and the median post-venipuncture age was <NUM> hrs.

The specimens were tested again about <NUM> hours later; the average post-venipuncture age with a SD was <NUM> ± <NUM> hrs and the median was <NUM> hrs. The blood was also tested at later times post-venipuncture in an attempt to establish a limit of acceptability with regard to the post-venipuncture age of the specimen.

Acceptably reproducible neutrophil functional activities were obtained over the initial <NUM> hrs post-venipuncture period, and as such, the combined venipuncture average (mean) with SD of <NUM> hrs ± <NUM> and a median of <NUM> hrs was used for analysis. The Subjects included <NUM> males and <NUM> females. The age range was <NUM> to <NUM> years with an average age of <NUM> and an SD of <NUM> and a median age of <NUM> years. A total of <NUM> measurements were taken.

The media employed included diluting media (DM), luminol balanced salt solution (LBSS) and lucigenin (dimethylbiacridinium dinitrate) balanced salt solution (DBSS). DM contained: <NUM> <NUM>-(N-morpholine) propanosulfonate (MOPS)-buffered balanced salt solution (<NUM> mEq/L Na+, <NUM> mEq/L K+, <NUM> mEq/L Cl-, <NUM> HnPO<NUM>; pH <NUM>; <NUM> ± <NUM> mOsmol/kg and endotoxin <<NUM> endotoxin units (EU)/mL. LBSS contained: <NUM> MOPS-buffered salt solution containing <NUM> mEq/L Na+, <NUM> mEq/L K+, <NUM> Ca<NUM>+, <NUM> Mg<NUM>+, <NUM> mEq/L Cl-, <NUM> HnPO<NUM>, plus <NUM> luminol (<NUM>-amino-<NUM>,<NUM>-dihydro-<NUM>,<NUM>-phthalazinedione) and <NUM> D-glucose; pH <NUM>; <NUM> ± <NUM> mOsmol/kg and endotoxin <<NUM> EU/mL. DBSS contained: <NUM> MOPS-buffered salt solution containing <NUM> mEq/L Na+, <NUM> mEq/L K+, <NUM> Ca<NUM>+, <NUM> Mg<NUM>+, <NUM> mEq/L Cl-, <NUM> HnPO<NUM>, plus <NUM> lucigenin (N,N'-dimethyl-<NUM>,<NUM>'-biacridinium dinitrate; aka bis-N-methylacridinium nitrate) and <NUM> D-glucose; pH <NUM>; <NUM> ± <NUM> mOsmol/kg and endotoxin <<NUM> EU/mL.

<FIG> shows the plot of chemiluminescence intensity (velocity) expressed as relative light units (RLU/sec) measured over a <NUM> interval plotted against the time interval of testing for first two subjects tested. The potassium ethylenediaminetetraacetate (K<NUM>EDTA)-anticoagulated whole blood specimens were initially diluted with DM and tested at a final dilution of <NUM> to <NUM>. Testing was performed in triplicate. A <NUM>µL equivalent volume of blood was used per test. Activation of phagocyte respiratory burst metabolism was initiated on addition of the diluted blood to a microplate well coated with <NUM> nanomole (nmol) phorbol <NUM>-myristate <NUM>-acetate (PMA), i.e., stimulus, and containing balanced salt solution with a chemiluminigenic probe, i.e., lucigenin or luminol. The final volume per well was <NUM>µL.

Measurements were taken at <NUM> <NUM> sec intervals using an Orion II microplate luminometer (Titertek Berthold) at a temperature of <NUM>. For example, the absolute leukocyte count (white blood count; WBC) for Subjects <NUM> and <NUM> were <NUM>/<NUM>µL and <NUM>/<NUM>µL blood, respectively, and the absolute neutrophil counts (ANC) for Subjects <NUM> and <NUM> were <NUM>,<NUM>/<NUM>µL and <NUM>/<NUM>µL, respectively. The post-venipuncture age of the blood specimens for Subjects <NUM> and <NUM> were <NUM> hrs <NUM> and <NUM> hrs <NUM>, respectively.

For each Subject, twelve chemiluminescence (CL) intensity measurements were taken over a <NUM> interval. As depicted in <FIG>, CL activity is measured as intensity, i.e., a velocity, and expressed as relative light units per second (RLU/sec). As such, the plotted data illustrate the change in CL intensity (velocity) with respect to time. It is important to appreciate that CL measurements are velocity (rate) measurements whereas most techniques measure accumulation of product or depletion of substrate, i.e., integral values.

For some comparisons, it may be appropriate to express CL as an accumulated RLU, i.e., integral or summation value, over a selected time interval of testing. The CL velocity (RLU/sec) values can be converted to integral CL expressed as RLU values by summation of the area under the RLU/sec plots over the interval of testing.

<FIG> presents the CL data of <FIG> expressed as the total or integral RLU's accumulated during the time interval of measurement. Integral expression of CL may be preferable when relating CL to other integral values, such as the number of neutrophils present in the volume of blood tested.

For comparison, regression analyses of integral CL values are plotted against the type of leukocyte present for blood specimens tested as illustrated in <FIG> A, B, C and D. As depicted in <FIG>, there is some correlation, i.e., R<NUM> = <NUM>, of lucigenin luminescence with the total leukocyte count. The majority of leukocytes in blood are phagocytes, and the majority of these phagocytes are neutrophils. The correlations of lucigenin CL with the phagocyte and neutrophil counts are good, i.e., R<NUM>' s of <NUM> and <NUM>, respectively. Lucigenin CL shows no correlation with the lymphocyte count, i.e., R<NUM> =<NUM>.

Luminol CL is the product of simple (non-reductive) dioxygenation activity. With regard to phagocytes, luminol measures oxidase-driven MPO activities or eosinophil peroxidase activities. Lucigenin measures oxidase-dependent phagocyte reductive dioxygenation activity, and its CL activity is haloperoxidase independent. Measurement of phagocyte oxidase activity as lucigenin CL has advantage over luminol CL when the goal is quantifying the number of phagocytes present in blood or body fluids. Specific phagocyte NADPH oxidase activity, i.e., oxidase activity per phagocyte/neutrophil, is relatively constant and independent of variation in the MPO concentration per neutrophil. The MPO/neutrophil varies relative to the number of mitotic divisions in the myelocytic phase of myelopoiesis. Inflammatory or therapeutic increase in granulocyte colony forming factor (G-CSF) expands the promyelocytic pool where MPO is synthesized, and decreases the mitotic activity of the myelocytic pool. Each myelocyte division deletes the MPO per neutrophil by half. As such, stimulation and expansion of the promyelocytic pool and decreasing the number of divisions in the myelocytic pool result in larger neutrophils with increased MPO (Allen, Stevens et al.

Activated phagocyte NADPH oxidase activity is responsible for reductive dioxygenation activity and is measured as lucigenin CL activity. This same oxidase activity drives haloperoxidase-dependent simple (non-reductive) dioxygenation activities. Phagocyte luminol-dependent CL activity reflects haloperoxidase, especially MPO, activity. The graphics and regression analyses of <FIG> A, B, C and D show that unlike neutrophil specific oxidase activity, that correlates with the neutrophil count, luminol CL that is MPO dependent is more variable. The luminol CL per neutrophil varies with the state of host inflammation and with G-CSF or GM-CSF treatment (Allen, Stevens et al. The difference between simple (nonreducing) dioxygenation activity and reductive dioxygenation can be appreciated by comparing the integral luminol CL regression analyses of <FIG>to the integral lucigenin CL regression analyses of <FIG> Note that reductive dioxygenation (lucigenin CL) plotted against neutrophils shows greater correlation with phagocytes/neutrophils, i.e., R<NUM> = <NUM>, than simple (non-reductive) dioxygenation (luminol CL) plotted against the neutrophil present R<NUM> = <NUM>. As with lucigenin CL, there is no correlation of luminol CL with the lymphocyte count, i.e., R<NUM> =<NUM>.

In <FIG> and <FIG>, note that the two Subjects with the highest phagocyte/neutrophil counts (two uppermost right graph points) also show high specific oxidase-driven MPO activities. High neutrophil counts and high specific MPO activities suggest G-CSF-stimulated myelopoiesis usually in response to immune-physiologic stimulation or therapeutic intervention (Allen, Stevens et al.

As illustrated in <FIG> A and B, the plots of integral luminol and lucigenin CL per neutrophil (i.e., specific activity/neutrophil) versus the age of the blood post-venipuncture show that the CL activity per neutrophil remains relatively constant during the initial post-venipuncture <NUM>-hour interval using either luminol or lucigenin as the chemiluminigenic probe. After this initial period, neutrophil oxidase and oxidase-driven MPO activities decrease exponentially. As previously described, luminol CL activity shows more variance than lucigenin CL activity without regard to post-venipuncture age. The R<NUM>'s for the composite luminol and lucigenin CL activities per neutrophil measurements are <NUM> and <NUM>, respectively. The lower R<NUM> observed for luminol CL is consistent with the previously described variation in MPO per neutrophil.

The post-venipuncture functional lifetime is essentially the same whether neutrophil oxidase or oxidase-driven myeloperoxidase activity is measured. As illustrated in <FIG> and <FIG> for the individual Subjects <NUM> and <NUM>, both oxidase-driven MPO activity per neutrophil, i.e., luminol CL, and the oxidase activity per neutrophil, i.e., lucigenin CL, show exponential decreases relative to post-venipuncture age of the blood neutrophil. The function of the hexose monophosphate shunt enzymes that provide the reducing equivalents driving both NADPH oxidase and NADPH oxidase-driven MPO activities are susceptible to age-related loss of function.

When the exponential relationships for each individual Subjects are averaged together, the relationship of luminol CL to post-venipuncture age for <NUM> Subjects with four complete measurements out to <NUM> hours was y = 59780e-<NUM>. 026X with a R<NUM> ± StdDev of = <NUM> ± <NUM>. The relationship of lucigenin CL to post-venipuncture age for <NUM> Subjects with four complete measurements out to <NUM> hours was y = 55404e-<NUM>. 024X with a R<NUM> ± StdDev of = <NUM> ± <NUM>.

In conclusion, chemiluminigenic probing of phagocyte and especially neutrophil NADPH oxidase activity can be applied to measuring neutrophils in blood and body fluids. Oxidase function per neutrophil is best measured using lucigenin (DBSS: N,N'-dimethyl-<NUM>,<NUM>'-biacridinium dinitrate (lucigenin) balanced salt solution) as the chemiluminigenic probe. Such lucigenin CL correlates with the number of phagocytes/neutrophils in the sub-microliter quantity of whole blood or body fluid tested. The functional activity of phagocytes in EDTA anticoagulated blood is relatively well maintained during the initial <NUM>-hour post-venipuncture period. After this initial period, neutrophil functional capacity, measured as either oxidase activity using lucigenin CL or oxidase-driven MPO activity using luminol CL, decreases exponentially with respect to post-venipuncture age.

Luminol CL measures NADPH oxidase-driven MPO activity per neutrophil. The MPO content per neutrophil is variable and is dependent on the state of myelopoietic stimulation. Cell size, azurophilic granule content and MPO per neutrophil increase following immunologic generation of or therapeutic treatment with G-CSF (Allen, Stevens et al. <NUM>, Allen, Dale et al. Consequently, the ratio of oxidase-driven MPO (luminol CL) activity to oxidase (lucigenin CL) activity provides useful information with regard to treatment or immune-physiologic stimulation of neutrophil myelopoiesis.

As used herein, "about," "approximately" and "substantially" are understood to refer to numbers in a range of numerals, for example the range of -<NUM>% to +<NUM>% of the referenced number, preferably -<NUM>% to +<NUM>% of the referenced number, more preferably -<NUM>% to +<NUM>% of the referenced number, most preferably -<NUM>% to +<NUM>% of the referenced number.

Furthermore, all numerical ranges herein should be understood to include all integers, whole or fractions, within the range. Moreover, these numerical ranges should be construed as providing support for a claim directed to any number or subset of numbers in that range. For example, a disclosure of from <NUM> to <NUM> should be construed as supporting a range of from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, and so forth.

As used herein and in the appended claims, the singular form of a word includes the plural, unless the context clearly dictates otherwise. Thus, the references "a," "an" and "the" are generally inclusive of the plurals of the respective terms. For example, reference to "a stimulus" or "the stimulus" includes a plurality of such stimuli. The term "and/or" used in the context of "X and/or Y" should be interpreted as "X," or "Y," or "X and Y. " Similarly, "at least one of X or Y" should be interpreted as "X," or "Y," or "both X and Y.

Similarly, the words "comprise," "comprises," and "comprising" are to be interpreted inclusively rather than exclusively. Likewise, the terms "include," "including" and "or" should all be construed to be inclusive, unless such a construction is clearly prohibited from the context. However, the embodiments provided by the present disclosure may lack any element that is not specifically disclosed herein. Thus, a disclosure of an embodiment defined using the term "comprising" is also a disclosure of embodiments "consisting essentially of" and "consisting of" the disclosed components.

Where used herein, the term "example," particularly when followed by a listing of terms, is merely exemplary and illustrative, and should not be deemed to be exclusive or comprehensive. Any embodiment disclosed herein can be combined with any other embodiment disclosed herein unless explicitly indicated otherwise.

Claim 1:
A method of assessing myelopoietic suppression, or neutrophil consumption in response to infection, in a sample of whole blood of an animal, the method comprising:
diluting a sample of whole blood which has been obtained from the animal <NUM> to <NUM> with diluting medium;
contacting the sample of diluted whole blood with:
(i) a substance that activates NADPH oxidase-dependent respiratory burst metabolism of the neutrophils present in the sample of whole blood; and
(ii) a chemiluminigenic substrate susceptible to reductive dioxygenation by the activated NADPH oxidase to yield chemiluminescence, wherein the chemiluminigenic substrate is lucigenin (N,N'-dimethyl-<NUM>,<NUM>'-biacridium dinitrate); and
quantifying the resulting reductive dioxygenation of lucigenin by measuring the emitted chemiluminescence of lucigenin using a hand-held or portable luminometer, wherein the amount of chemiluminescence is a measurement of absolute neutrophil function of the neutrophils present in the sample,
wherein the absolute neutrophil function is proportional to the absolute neutrophil count, and
wherein the absolute neutrophil count is used to assess myelopoietic suppression, or neutrophil consumption in response to infection, in the animal.