Abstract: The present invention relates to the field of immunology and hyperproliferative diseases. More specifically, the present invention relates to a method of detecting and monitoring therapeutic antibody:antigen complex, soluble antigen and soluble therapeutic antibody, wherein a patient has undergone at least one course of immunotherapy. Yet further, levels of therapeutic antibody:antigen complexes, soluble antigens or soluble therapeutic antibodies may be measured and used to stage or monitor a hyperproliferative disease.

Abstract: The invention provides compositions and methods for cell separation. These reagents and techniques specifically agglutinate cells via surface antigen recognition and can be used to recover even rare cell types in high yield.

Abstract: A cell permeabilization and stabilization reagent and method of use are disclosed. The reagent contains a N-acyl sarcosine or a salt thereof, a pH adjusting agent to adjust pH of the reagent in a range from about 4 to about 6; and an aqueous medium; the reagent having a low ionic strength defined by a conductivity of less than 9.0 mS/cm. The reagent further contains bovine serum albumin and glycerol. The reagent may further include an alkyl sulfate surfactant. Upon incubating the cells with the reagent, the reagent permeates the cellular membrane to allow penetration of an intracellular marker, causes intracellular protein aggregation within the cellular membrane, while preserves a cellular constituent for binding with a cellular marker for subsequent analysis by flow cytometry.

Abstract: The invention provides for a process for preparing a sensitivity control for blood group determination including dissolving an amount of an antigen in water to give an antigen solution of known concentration, contacting the antigen solution with cells to allow insertion of antigen molecules into the cell membranes of the cells to give transformed cells or contacting the antigen solution with cells that have been modified by the insertion of a linker molecule into the membranes of the cells to allow attachment of antigen molecules to the linker molecules to give transformed cells, washing the transformed cells to give a transformed cell solution, and determining the concentration of the transformed cell solution to enable the solution to be used as a sensitivity control for blood group determination.

Abstract: Methods for differentially identifying cells in an instrument employ compositions containing a combination of selected antibodies and fluorescent dyes having different cellular distribution patterns and specificities, as well as antibodies and fluorescent dyes characterized by overlapping emission spectra which form non-compensatable spectral patterns. When utilizing the compositions described herein consisting of fluorescent dyes and fluorochrome labeled antibodies with overlapping spectra that cannot be separated or distinguished based upon optical or electronic compensation means, a new fluorescent footprint is established. This new fluorescent footprint is a result of the overlapping spectra and the combined cellular staining patterns of the dyes and fluorochrome labeled antibodies chosen for the composition. The new fluorescent footprint results in histogram patterns that are useful for the identification of additional cell populations or subtypes in hematological disease.

Abstract: A method for enumerating white blood cells and nucleated red blood cells. The steps of the method are as follows: (a) providing a lysed sample of whole blood; (b) introducing the lysed sample to a light-scattering multi-angle depolarizing flow cytometer; (c) removing depolarizing interference, e.g., lipid droplets and other measured particles; (d) differentiating nucleated red blood cells and noise from white blood cells in the absence of depolarizing interference; (e) differentiating nucleated red blood cells from noise in the absence of depolarizing interference and white blood cells; and (f) differentiating possible platelet clumps.

Abstract: Disclosed is a single population of simulated leukocyte granules prepared from mammalian whole white blood cells, which is useful in calibrators for a hematology analyzer, a calibrator which includes the single population of simulated leukocyte granules. Disclosed is also a method of preparing the single population of simulated leukocyte granules. The method of preparing single population of simulated leukocyte granules includes the actions of: obtaining mammalian whole white blood cells; treating the mammalian whole white blood cells with a hemolytic agent and a leukocyte treating liquid which includes an isotonic saline solution. The isotonic saline solution may include a fixative, an oxidizer, and a carbohydrate compound; fixing the treated mammalian whole white blood cells with a fixative; and suspending the fixed cells in a preservation medium for long-term preservation of fixed cells.

Abstract: The invention relates to a reagent and a process for the identification and counting of biological cells in a sample. This reagent comprises a cell lysing agent selected from at least one detergent in a concentration capable of specifically lysing a given type of cells in the sample, and a stain capable of marking the intracellular nucleic acids of the remaining unlysed cells. Application in particular for the identification and counting of cells using an automated analysis system based on flow cytometry.

Abstract: The instant invention provides an economical flow-through method for determining amount of target proteins in a sample. An antibody preparation (whether polyclonal or monoclonal, or any equivalent specific binding agent) is used to capture and thus enrich a specific monitor peptide (a specific peptide fragment of a protein to be quantitated in a proteolytic digest of a complex protein sample) and an internal standard peptide (the same chemical structure but including stable isotope labels). Upon elution into a suitable mass spectrometer, the natural (sample derived) and internal standard (isotope labeled) peptides are quantitated, and their measured abundance ratio used to calculate the abundance of the monitor peptide, and its parent protein, in the initial sample.

Abstract: A method for distinguishing erythrocytes in a biological specimen, includes preparing a sample liquid so as to cause damage to a cell membrane of yeast-like fungi without hemolyzing erythrocytes in a biological specimen and to stain the yeast-like fungi with a fluorescent dye; detecting a first information and a second information from a particle in the sample liquid, wherein the first information reflects a size of the particle and the second information reflects a degree of fluorescent staining of the particle; and distinguishing the erythrocytes from the yeast-like fungi based on the first information and second information detected. An apparatus, a reagent kit and a reagent for carrying out the method are also disclosed.

Abstract: A method useful for the enumeration of cell populations in a biological sample includes the steps of reacting in a single reaction mixture a sample, a first antibody labeled with a fluorochrome having a first emission spectrum and an additional antibody. The first antibody binds to an antigenic determinant differentially expressed on leukocytes and non-leukocytes. The additional antibody binds to an antigenic determinant differentially expressed on mature and immature granulocytes or myeloid cells, and is labeled either with the first fluorochrome or an additional fluorochrome having an emission spectrum distinguishable from the first emission spectrum. The reaction mixture can be mixed with a nucleic acid dye having an emission spectrum that overlaps with one of the first or additional emission spectra. The reaction mixture may be treated with a lytic system that differentially lyses non-nucleated red blood cells and conserves leukocytes.

Abstract: A reagent for analyzing immature leukocyte capable of analyzing accurately immature leukocyte such as myeloblast and immature granulocyte, and mature leukocyte, which reagent has broader allowable range of sample processing conditions than conventional ones, and a reagent kit are provided. The present invention relates to a reagent for analyzing immature leukocyte containing a surfactant for giving damage to cell membrane of red blood cell and mature leukocyte in the sample, a solubilizing agent for causing contraction to damaged blood cell, sugar, a dye for staining nucleic acid.

Abstract: A diagnostic method and associated test kit for detecting an analyte residing in a test sample is provided. The kit includes a housing, and a membrane disposed within the housing having a detection region and a collection region. A blood sample meter is provided having a first end for absorption of a blood sample, a filtering section adjacent to the first end that filters red blood cell components from the blood sample, and a storage section adjacent to the filtering section that receives plasma or serum from the filtering section. An opening in the housing is sized for insertion of the sample meter into the housing such that the storage section of the sample meter is disposed in fluid communication with the collection region of the membrane. The plasma or serum is transferred from the storage section of the sample meter to the collection region of the membrane for subsequent migration to the detection region.

Abstract: A control and a cellular fraction for use therein and methods for making the same, including a first cellular component including a plurality of a first group of processed animal red blood cells other than human blood cells; a second cellular component including a plurality of a second group of processed animal red blood cells other than human blood cells; a third cellular component including a plurality of a third group of processed animal red blood cells other than human blood cells; wherein one or more of the first second and third cellular components include a nucleus; and the control simulates erythroblasts of a human blood sample on an automated blood analyzer that analyzes blood cells using impedance, optical measurements or both.

Abstract: The invention provides a method for creating a standard for multiple analytes comprising treating a portion of a sample to substantially remove analytes of interest to produce a series of specifically deficient samples; and determining and mixing an appropriate amount of the series of specifically deficient samples to create a standard. The analyte may be any substance to be measured.

Abstract: The invention provides compositions and methods for cell separation. These reagents and techniques specifically agglutinate cells via surface antigen recognition and can be used to recover rare cell types in high yield.

Abstract: The present invention relates to methods of detecting the presence of detergent- or urea-insoluble amyloid-like fibrils or protein aggregates on filters. Preferably, said fibrils or aggregates are indicative of a disease, preferably of a neurodegenerative disease such as Alzheimer's disease or Huntington's disease. In addition, the present invention relates to inhibitors identified by the method of the invention, to pharmaceutical compositions comprising said inhibitors and to diagnostic compositions useful for the investigation of said amyloid-like fibrils or aggregates.

Abstract: The present invention provides a method for preparing a five-part differential white blood cell control and a white blood cell control prepared thereby. The white blood cell control obtained by the method of the present invention perfectly retains the light scattering properties of every type of white blood cells and has much higher stability than that of real white blood cells, and therefore can be used for the quality control of five-part differential hematology analyzers based on the principle of multi-angle light scattering.

Abstract: A whole-blood-based substitute composition that is useful in coagulation assays as a standard, reference, control, calibrator, linearity verifier, or training material is prepared by combining a red blood cell lysate that is free of plasma, leukocytes, and platelets with a platelet-free plasma of human origin and an antimicrobial agent.

Abstract: Disclosed is a composition that synergistically prevents proteolysis or modification of peptides in sampled biological fluids using sulfonyl fluoride family protease inhibitors at high concentrations combined with at least one additional protease inhibitor of a different type, preferably a broad spectrum protease inhibitor, and a chelator. A preferred embodiment uses AEBSF at 10 mM, Benzamidine at 20 mM and EDTA as the chelator. The disclosed composition may be combined with other protease inhibitors to further modulate its specificity, for instance to additionally target acidic proteases. Additional protease inhibitors, reducing agents, stabilizers and buffering agents may be combined with the disclosed compositions in devices for sampling or testing biological fluids for levels of peptides of interest, or methods therefore. The disclosed devices, compositions and methods are of particular use in sampling and testing for the level of natriuretic peptides.

Abstract: Disclosed is a method for testing a modified specimen such as a dried blood spot, plasma or serum specimen, for an analyte of interest, such as cholesterol. In accordance with the disclosed subject matter, the level of the analyte of interest in the medium from which the modified specimen was obtained (e.g., from a patient's blood) is determined based on the level of an analyte in a solution formed from the modified specimen and on the level of at least one normalizing analyte. The analyte and normalizing analyte each may be an ion, compound, biochemical entity, or property of the specimen. Also disclosed are a fluid collector and a fluid collection device.

Abstract: An apparatus includes semiconductor processing equipment. A particle detecting integrated circuit is positioned in a vacuum environment, the particle detecting integrated circuit containing a device having a pair of conductive lines exposed to the vacuum environment. The pair of conductive lines is spaced at a critical pitch corresponding to diameters of particles of interest. A computer system is linked to the particle detecting integrated circuit to detect a change in an electrical property of the conductive lines when a particle becomes lodged between or on the lines.

Abstract: Provided herein are reagents for use in an automated environment for cell conditioning of biological samples wherein the cells or tissues are predisposed for access by reagent molecules for histochemical and cytochemical staining procedures. The reagents include, but are not limited to, components optimized to facilitate molecular access to cells and cell constituents within the biological sample. Also provided herein are reagents for use in an automated environment for removing or etching embedding media by exposing a biological sample to be stained in histochemical or cytochemical procedures without the dependence on organic solvents. The reagents include, but are not limited to, components optimized to facilitate removal or etching of the embedding media from the biological sample.

Abstract: The object of the invention is formulations and methods without chaotropic components for the isolation of nucleic acids with binding to a solid phase, in particular of DNA, from arbitrary complex starting materials containing a lysis/binding buffer system manifesting at least one anti-chaotropic salt component, the concentration of the anti-chaotropic salt components being between 0.001 mM and 0.1 M, preferably 0.1 mM, and further a solid phase and washing and elution buffers which are known per se. The lysis/binding buffer system can exist as an aqueous solution or as a solid formulation in ready-to-use reaction vessels. As a solid phase, all carrier materials applied for isolation by means of chaotropic reagents can function, preferably glass fibre fleeces, glass membranes, silicone carriers, ceramics, zeoliths or materials possessing negatively functionalised surfaces or manifesting chemically modified surfaces which can be converted to a negative charging potential.

Abstract: The present invention provides fluorescent dye compounds and methods of using the compounds for the staining of nucleic acids. In particular, the dye compounds comprise heterocyclic molecules with hydroxy alkyl and aromatic substituents, and the dye compounds form highly fluorescent complexes upon nucleic acid binding.

Abstract: 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.

Abstract: Provided is a method of lysing a cell or a virus using a free radical. The method includes: applying an electric field to a mixture of a metal ion, a peroxide, and a cell or virus solution to increase the free radical generation, thereby lysing a cell or a virus. In the present method, cell lysis may be efficiently performed using a low electrical energy (several mV to several V). When the present method is applied to a microsystem, cell lysis can occur at a desired time and in a desired space by controlling the electrical energy, thus being suitable to realize a lab-on-a-chip (LOC).

Abstract: The invention relates to measuring of the adhesion of platelets ex vivo. In this method, monodisperse polymer particles are added to blood, and the number of platelets in the blood are measured before and after shaking of the sample. The level of adhesion of the platelets is determined by comparing the number of platelets prior to shaking with the number of platelets after shaking. Methods of establishing an adhesion index and diagnosis of a patient are also provided.

Abstract: Methods of prevention and correction of white blood cell interferences to the measurements of mean cell volume (MCV), red blood cell concentration (RBC) and hematocrit (Hct) of a blood sample are disclosed. The interference to MCV can be prevented by identifying a valley between the red blood cell and white blood cell modes on the red blood cell distribution histogram, defining a red blood cell region using the valley and calculating MCV within the defined region. Alternatively, a curve fit of the white blood cell population on the red blood cell distribution histogram can be used to exclude the white blood cells. RBC can be corrected by subtracting the white blood cell concentration obtained from the analysis of a second aliquot sample, when the white blood cell concentration (WBC) exceeds a predetermined criterion. Hct of the blood sample can be calculated using the obtained MCV and RBC.

Abstract: Red blood cells from a vertebrate are treated to make them effective components of a hematology control, allowing the control to be used for detecting all blood cell components, including white blood cells and platelets. The treatment includes the use of a fixative under limited conditions of concentration and exposure time, and the resulting red blood cells are stable but lysable in a hematology instrument and have a reduced tendency to form particulates.

Abstract: The invention provides compositions and methods for cell separation. These reagents and techniques specifically agglutinate cells via surface antigen recognition and can be used to recover even rare cell types in high yield.

Abstract: A method for classifying leukocytes in animal blood is described. In the method, a measurement sample is prepared by mixing a canine or feline blood sample with a lysing reagent. Erythrocytes are lysed and leukocytes are shrunk in the measurement sample. The data correlated with the size of leukocytes in the measurement sample are measured. The leukocytes, on the basis of the measured data, are classified into a first group containing lymphocytes, a second group containing neutrophils and monocytes and a third group containing eosinophils.

Abstract: A lytic reagent composition and methods for differential analysis of leukocytes are disclosed. In embodiments, the analysis may utilize optical measurements in flow cytometry based hematology analyzers. The reagent system includes an anionic surfactant in a hypotonic solution, an inorganic buffer to maintain the pH in a range from about 6 to about 10, and optionally a leukocyte stabilizer. The reagent system is used to lyse red blood cells and stabilize the leukocytes to enable multi-part differentiation of leukocytes in a near physiologic pH environment on a flow cytometry based hematology analyzer using axial light loss, light scatter intensity, high-numerical aperture side scatter, and time-of-flight measurements.

Abstract: The present invention relates to a method for the early diagnosis of cancer in a subject, which is based on determination of the relative fraction of microorganisms derived from the feces of the subject, as compared to the total count of microorganisms in the same of corresponding sample. This relation has been found to be indicative of the presence or absence of cancer in said subject. After isolating at least one of the microorganisms from the fecal sample to form a so-called diagnostic sample, and incubating, for a sufficient time, the diagnostic sample with cancer cells. The microorganism being in an amount corresponding to its relative fraction in the original fecal sample, the cancerolytic activity of the microorganism/s is indicative to the presence or absence of cancer cells in the subject. The cancerolytic activity is expressed by terms of a tumor cell necrosis index (TCNI).

Abstract: A microfluidic system for isolation and amplification of DNA or RNA from aqueous solutions and detection of the DNA or RNA on a lateral flow detection strip, including a disposable microfluidic card for use in analysis of bacteria in platelets and an analysis of sexually transmitted diseases (STD) in urine. The card will include an embedded membrane that filters out cells and cellular debris. Any biological debris on the membrane will be lysed and the DNA or RNA amplified via PCR amplification protocol, including appropriate reagents and thermal cycling conditions. The amplified DNA or RNA are transferred to a lateral flow detection strip for a visual diagnostic read out. An alternate embodiment includes a microfluidic card for use in typing antiglobulin assays.

Abstract: A reagent for classifying leucocytes, including: a) at least one of surfactant selected from a cationic surfactant, an amphoteric surfactant, and the combination thereof; b) an organic compound having phenyl or heterocyclic group, wherein when the surfactant is a cationic surfactant, the organic compound is an organic compound having an anionic group; when the surfactant is an amphoteric surfactant or a combination of amphotheric and cationic surfactant, the organic compound is an organic compound having an anionic or cationic group; c) a buffer for adjusting pH.

Abstract: The present invention relates to a reagent for classifying leukocytes including (a) at least one surfactant capable of lysing erythrocytes and partly damaging the cell membrane of leukocytes, (b) at least one organic compound bearing an anionic group capable of binding to the cationic component present in the leukocytes to provide morphological differences between the leukocytes, and (c) a buffer for adjusting pH to 2˜8. Also disclosed is a method for classifying leukocytes into four groups.

Abstract: The present invention relates to the estimation of the amount of subtypes of specific cells, for example the number of certain subtypes of leukocytes, by measurements of unique proteins in extracts of blood and other biological material. The knowledge of the number or amount of specific subtypes of white cells is important in the clinical diagnosis and surveillance of subjects with inflammatory disease including infectious disease, cancer, allergy/asthma etc.

Abstract: A lytic reagent composition and methods for differential analysis of leukocytes are disclosed. In embodiments, the analysis may utilize optical measurements in flow cytometry based hematology analyzers. The reagent system includes an anionic surfactant in a hypotonic solution, an inorganic buffer to maintain the pH in a range from about 6 to about 10, and optionally a leukocyte stabilizer. The reagent system is used to lyse red blood cells and stabilize the leukocytes to enable multi-part differentiation of leukocytes in a near physiologic pH environment on a flow cytometry based hematology analyzer using axial light loss, light scatter intensity, high-numerical aperture side scatter, and time-of-flight measurements.

Abstract: The present invention relates to an apparatus and a process for the high-throughput, quick screening, optimization, regeneration, reduction and activation of catalysts. More specifically, the present invention is a method and apparatus to quickly screen, optimize and regenerate multiple fast deactivating catalysts while maintaining a predefined range of time-on-stream.

Abstract: The present invention relates to a hematology instrument system that discriminates platelets from red blood cells, debris and other particles within a blood sample. The instrument system uses an optical trigger and collects data at optical sensor locations relative to a flow cell-illuminating laser beam's optical axis. An axial sensor measures axial light loss due to a particle in the flow cell's illumination aperture. In addition, the instrument system can include an RF unit generates electrical parameters, such as DC and RF parameters, within the flow cell. Blood specimens can be prepared with and without a sphering agent.

Abstract: Disclosed is an extracting solution for use in the extraction of a residual veterinary drug in livestock product or seafood. The extracting solution contains 0.05 to 1% of metaphosphoric acid and comprises a buffer solution of pH 5.5 to 7.5. The extracting solution can extract plural veterinary drugs at the same time, and can be used preferably used for the extraction when the residual veterinary drug is an antibacterial substance. By using the extracting solution, it becomes possible to extract plural veterinary drugs efficiently at the same time without impairment of stability because of its neutral pH range. Hence, the extracting solution enables to determine a residual veterinary drug in livestock product or seafood rapidly in a simple manner.

Abstract: A composition is disclosed which is capable of being used for detection, comprising an encapsulated noble metal nanocluster. Methods for preparing the encapsulated noble metal nanoclusters, and methods of using the encapsulated noble metal nanoclusters are also disclosed. In certain embodiments, the noble metal nanoclusters are encapsulated by a dendrimer, a peptide, a small organic or inorganic molecule, or an oligonucleotide. The encapsulated noble metal nanoclusters have a characteristic spectral emission, wherein said spectral emission is varied by controlling the nature of the encapsulating material, such as by controlling the size of the nanocluster, the generation of a dendrimer, the incorporation of a functional group, and wherein said emission is used to provide information about a biological state.

Abstract: The present invention provides a method of determining the presence or amount of newly synthesized antibody in a sample in response to an immunogen by detecting the released antibodies or parts thereof in a sample containing lymphocytes which have been disrupted whereby to release the synthesized antibodies or parts thereof associated with said lymphocytes whereby to determine the presence or amount of newly synthesized antibody in said sample, methods of diagnosis using said method and kits for performing the method. The method may also be modified to allow detection of non-specific infection indicators.

Abstract: A B-lymphocyte classifying method includes the steps of (1) preparing a measurement sample by mixing a blood sample with a lysing reagent to lyse erythrocytes and to shrink the B-lymphocytes in the blood sample, (2) letting the measurement sample flow through a flow cell of a flow cytometer, (3) radiating a light beam onto a cell in the measurement sample that is flowing through the flow cell, (4) detecting at least two scattered light emitted from the irradiated cell, (5) specifying a region of a B-lymphocyte cluster in accordance with the detected scattered light, and (6) counting the number of B-lymphocytes in the specified region.

Abstract: A method and apparatus for preparing biological cell samples for intracellular analysis. The invention is based upon the recognition that many of the steps of the conventional methods for such sample preparation can be eliminated, leading to a process that readily lends itself to automation and the advantages associated therewith. The method of the invention comprises the steps of (a) cell-fixation, (b) permeabilization and (c) staining (or labeling) of intracellular molecules of interest by probes that are readily detectable by flow cytometric techniques, all without any intervening cell-washing (and re-suspension) steps. Rather, the single cell-washing step is effected after these three steps have been carried out. Preferably, the washing step is carried out by passing the fixed, permeabilized and stained cell sample through a semi-permeable membrane that serves to filter out (by transmission) interferants to waste while retaining the cells of interest.

Abstract: A reference control composition containing a nucleated red blood cell component and the method of making are disclosed. The reference control composition includes a nucleated red blood cell component made of fixed non-nucleated blood cells and a suspension medium. The non-nucleated blood cell has a natural cell size substantially similar to a size of nucleus of said nucleated red blood cell of said blood sample. The nucleated red blood cell component can be made of equine, ovine, bovine, feline, canine, or porcine red blood cells; and it is substantially free of nucleic acid. The reference control composition can further include a white blood cell component, a red blood cell component, a platelet component, a reticulocyte component, or combinations thereof. Further disclosed are the methods of using the reference control composition for measurement of nucleated red blood cells on a blood analyzer.

Abstract: The invention provides a flow cytometric method for measuring dendritic cell function in whole blood, comprising: (a) contacting a whole blood sample with a dendritic cell activator; (b) adding to the sample a plurality of dendritic cell-distinguishing antibodies and at least one cytokine-specific antibody; and then (c) flow cytometrically assaying the sample for the binding of the cytokine-specific antibody by at least one distinguishable DC subset. Other assays are presented in which DC activation markers are assessed.

Abstract: A method for discriminating and quantifying platelets within an analyzed blood sample involves initially diluting the blood sample with a ghosting reagent that causes a change in the index of refraction of the red blood cells. Owing to the change in the index of refraction, light scattered from the ghosted red blood cells will be substantially reduced relative to light scattered from platelets. This results in locations of platelets within a scatterplot of the analyzed blood sample to fall within a region distinguishable from those containing normal red blood cells, fragmented red blood cells, and microcytic red blood cells.

Abstract: In a method for measuring an analyte, which comprises a reaction step of forming a reaction system including a sample containing whole blood, a first substance carried by a solid carrier and specifically binding to an analyte contained in the sample and a second substance specifically binding to the analyte and allowing the analyte to react with the first and second substances and a measurement step of measuring the formed reaction product, (1) the reaction step is performed in a state that blood cells are not disrupted, and (2) at least the reaction step is performed in the presence of a sufficient amount of a detergent that does not cause hemolysis, does not inhibit reactions of the analyte with the first and second substances specifically binding to the analyte and can prevent influence on the reaction system of a component existing in the reaction system.