Abstract: The invention teaches a method for determining an analyte in a liquid sample via a heterogeneous assay. The sample is contacted to a carrier material which contains, in addition to one of a labelled analyte analogous substance or a labelled analyte specific substance, a detectable component which does not influence immunological reactions occurring during the course of the assay. A solid phase bound component, which is either an insufficient amount of analyte specific substance or an excess of analyte relative to analyte in the sample is contacted to the sample so as to accomplish formation of solid phase bound complexes. After separation of liquid and solid phase, label is measured in one of these, and the detectable substance is measured in the liquid. Correlation of the values obtained leads to determination of the analyte. Also described is a reagent used in the described method.

Abstract: Screening methods to obtain suitable antibodies for use in immunoassays for analytes not ordinarily susceptible to detection by these methods involves in vitro screening of panels of cells secreting a representative selection of antibodies. An application of this method also permits the preparation of specific mimotopes which mimic the immunological activity of the desired analyte, which mimotopes can then be used as competitors in the immunoassay or can be used to immunize subject mammals in order to improve the specificity and affinity of the antibodies. Methods to identify a particular analyte by its pattern of binding strength to a panel of related antibodies and to match an arbitrary analyte with an immunoreactive member of a panel of candidate antibodies are also disclosed. These screening methods can also be employed for rational drug design.

Abstract: The invention is directed to labeled drug hapten analogues comprising:(A) a label, of the type used in immunoassays, having an amine or sulfhydryl group;(B) a drug hapten nucleus selected from barbiturates or hydantoins and(C) a linking chain linking the 3-position of the drug hapten nucleus to the label through a carbonyl bridge.

Abstract: The present invention is concerned with a method of assaying D-vanillylmandelic acid (D-VMA) contained in a specimen of a living organism through the following steps (A) to (D), and a reagent and a kit used for the assay, wherein a racemic mixture of VMA is used as the standard substance for preparing a calibration curve and a labeled anti-D-VMA antibody is used as the labeled anti-VMA antibody to specifically assay only D-VMA in the specimen:(A) the step of conducting a competitive reaction of VMA in the specimen and VMA in solid phase against the labeled anti-VMA antibody;(B) the step of separating the liquid phase from the solid phase;(C) the step of determining the quantity of labeling of the labeled anti-VMA antibody combined with the solid-phase VMA and that of other substances; and(D) the step of preparing a calibration curve or obtaining an equation by using a standard substance of a known concentration, calculating the concentration of VMA corresponding to the quantity of labeling determined in the s

Abstract: Derivatives of biologically active molecules containing a primary amine group and a hydroxylated nucleus, and their addition salts with mineral or organic acids, having general formula I:R'R"N--A--B--O--CH.sub.2 --CO--NH--R (I)A=linear or branched C.sub.1 -C.sub.5 alkylene;B=C.sub.4 -C.sub.10 aromatic nucleus with optional heteroatom, or=group --B.sub.1 --X--B.sub.2 --, wherein X=O or C.sub.1 -C.sub.4 alkylene;--NH--R=amine residue or alcohol residue; andR', R"=C.sub.1 -C.sub.5 alkyl, H or hydrophobic radical, and their addition salts with mineral or organic acids, method of preparation, applications, especially to visualization, purification, the preparation of antibodies and the assay of the total hormone, and as drugs, compositions in which they are present and analytical kits.

Abstract: Disclosed is a novel immunoassay methodology, bridge immunoassay, which employs a primary free solution analyte/receptor binding reaction, for example, in a sandwich-type format (two or more analyte receptors), in a competitive format (single analyte receptor) or in a related immunoassay format, and a universal solid phase and capture system. The universal capture system comprises a first receptor bound to a solid phase and a bridge receptor (a second receptor) which functions both as a ligand for said bound first receptor and as a receptor for a ligand conjugated to a sample analyte receptor (a third receptor). The bridge receptor is used to immobilize the immunocomplexes formed free in solution by linking them to the bound first receptor. The universal capture system can be used for assays for any analyte as the bridge receptor binds to a ligand, for example, a hapten or binding protein, conjugated to the sample analyte receptor. Methods, compositions and test kits for such bridge immunoassays are provided.

Abstract: The invention concerns monoclonal antibodies which are directed against the thrombin/hirudin-complex and derivatives thereof, processes for their preparation, hybridoma cell lines secreting said monoclonal antibodies, and processes for the preparation of the hybridoma cell lines. Furthermore, the invention relates to the use of the monoclonal antibodies and/or their derivatives for the determination of the thrombin/hirudin-complex as well as to test kits comprising said monoclonal antibodies and/or their derivatives.

Abstract: The stereochemistry of sialylation of an acceptor saccharide to obtain an .alpha. (2-3) or .alpha. (2-6) linkage is controlled to favor the a anomer by use of an aromatic ester of the sialyl reagent. The resulting intermediate .alpha. (2-3) and .alpha. (2-6) sialylated intermediate disaccharide blocks are useful in the synthesis of antigenic substances which can be used to raise antibodies useful in diagnosis and therapy, and can themselves be used as reagents in various applications. The preparation of the tetrasaccharide antigens corresponding to the 19-9 and sialyl-X antigens characteristic of malignant tissue illustrates the application of this method.

Abstract: The invention concerns a method for detecting an analyte in a blood sample or a derived fraction thereof. In this method one uses the binding affinity between the analyte and its specific binding agent. Moreover, a reaction component containing a peroxidase label is added to the sample and specific binding agent to form a reaction mixture. The incubation of the reaction mixture, containing the analyte and its specific binding agent, with the peroxidase-labeled reaction component has to be carried out in the presence of a quaternary ammonium salt or ionic surfactant.

Abstract: The present invention is directed to the measurement of soluble T cell growth factor receptors, soluble T cell differentiation antigens, or related soluble molecules or fragments thereof, and the use of such measurements in the diagnosis, staging, and therapy of diseases and disorders. Specific embodiments involve the diagnosis and monitoring of therapy using absolute values of such soluble molecules. Further embodiments involve detecting a change in the levels of such soluble molecules, in the diagnosis and therapy of diseases and disorders. In specific embodiments, measurements of interleukin-2 receptor levels can be made to detect lung cancer, or to stage squamous cell lung carcinoma. In other embodiments, detection of increases in both soluble IL2R and creatinine in the body fluid of a transplant patient can be used to differentially diagnose renal allograft rejection from infection.

Abstract: An automatic immunoassay apparatus utilizes cartridges each having at least two wells, a first well containing solid phase material carrying antigen or antibody, and a second well containing antibody or antigen labelled with labelling compound. The wells may be sealed with a suitable sealing film before use and the sealing film is broken when the cartridge is to be used. The cartridges are transported to a predetermined position on a steppingly movable reaction line and conveyed thereby at a predetermined interval. While the reaction line steps, a sample, labelled antigen or antibody contained in the second well and substrate, if necessary, are added to the first well and stirred at predetermined timings, and reactions between the sample and a reactive solution are measured under control of a control device having a memory storing operator selectable programs for various measuring methods.

Abstract: The present invention relates to a monoclonal antibody which specifically recognizes 6,15-diketo-13,14-dihydro-prostaglandin F.sub.1 .alpha. with high sensitivity, a hybridoma producing said monoclonal antibody, a method of establishing said hybridoma and an immunoassay method for 6,15-diketo-13,14-dihydro-prostaglandin F.sub.1 .alpha. using said monoclonal antibody.The monoclonal antibody of the present invention makes it possible to conveniently measure 6,15-diketo-13,14-dihydro-prostaglandin F.sub.1 .alpha., a stable metabolite of prostaglandin I.sub.2 thought of as reflecting the concentration changes therein, with specificity and high sensitivity. It is useful in determining the content of prostaglandin I.sub.2, which exhibits platelet aggregating inhibitory activity, vasodilating activity and other activities, in biological samples.

Abstract: The invention provides an anti Derf II monoclonal antibody selectively recognizing Derf II and belonging to an IgG or IgM class, the antibody being obtained by immunizing a mammal with Derf II antigen, which is derived from Dermatophagoides farinae.

Abstract: A method for diagnosing a patient with an autoimmune disease using monoclonal antibodies to quantitate the amount of 680 kd, 54 kd, 44 kd or 14 kd present, wherein an elevated amount of protein compared to a patient without the disease indicates the presence of autoimmune disease.

Abstract: A device and process for detecting the presence of organic molecular analytes in a fluid comprising a first binding component having a predetermined first affinity for specifically reversibly binding an analyte, a molecular conjugate of the analyte with a signal generating molecule that generates a detectable signal, and a second binding component having a predetermined second affinity for reversibly binding the signal generating molecule. In the presence of analyte, a fluid conducting system allows competitive binding of the analyte with the molecular conjugate and causes displacement of the conjugate and conducts the displaced conjugate to the second binding component. The signal generating molecule generates a detectable signal distinguishing binding thereof at the first or second binding components thereby indicating the presence of the analyte in the fluid.

Abstract: This invention relates to methods, reagents and kits for detection of normal or ectopic pregnancy, the termination of pregnancy, or increased risk of preterm labor and rupture of membranes. Each embodiment involves sampling from the vaginal cavity, and determining the presence or absence of a specific analyte in the test sample. Sandwich or competition assay procedures can be used. Reagents and reagent kits for the above assays are included. The kit contains anti-(fetal fibronectin) antibody and an anti-fibronectin antibody.

Abstract: The invention provides a process and products for the detection of the C peptide of relaxin in the body fluids of animals, as a positive indication of pregnancy. The invention may employ monoclonal antibodies generated to various epitopes on the C peptide.

Abstract: A method for immunoassay for a ligand is performed on a porous membrane with alkaline phosphatase as the label. The assay protocol includes a wash step with an organic acid to deactivate endogenous alkaline phosphatase. The invention includes a kit of materials for performing the assay.

Abstract: An aqueous composition useful for providing a chemiluminescent signal in analytical methods is stabilized by the presence of specific amounts of either a low molecular weight cationic surfactant or a cationic polymer. The composition also includes a 2,3-dihydro-1,4-phthalazinedione derivative, such as luminol, and 4'-hydroxyacetanilide. A chemluminescent signal is generated using the composition in the presence of peroxidase or a peroxidase-labeled specific binding species (such as an antibody or oligonucleotide).

Abstract: An analytical composition comprising antibody conjugate, an indicator which is capable of providing a detectable condition in the presence of peroxidase and hydrogen peroxide assays performed using this composition are described.

Abstract: A chromatographic test device for detecting the presence of an analyte in a liquid sample and incorporating at least two liquid-conductive zones (3, 4) which form separate liquid flow paths which deliver separate liquid streams to a region (8) in the test device during the test procedure, wherein control of the relative liquid flows in the separate flow paths is achieved, at least in part, by ensuring that at least one of the liquid flow paths is enhanced or made and/or broken or restricted during the course of the test procedure. Preferably such control is achieved by incorporating a liquid-swellable material (11) which is arranged to swell by contact with liquid sample and/or reagent and thereby to make or break contact between two liquid-conductive zones.

Abstract: Methods employing thyroid analog conjugates to enzymes and to immunogenic carriers are provided, which find use in the determination of thyroid compounds normally in physiological fluids, such as serum. The immunogenic carrier conjugates are used to raise antibodies specific to thyroid compounds. The antibodies and enzyme conjugates are used in assays for thyroid compounds. The thyroid analogs are characterized by the presence of only one phenyl ring that contains a hydroxyl substituent and one or two substituents in an ortho relationship to the hydroxyl substituent on the phenyl ring wherein the phenyl ring is conjugated to an enzyme or an immunogenic carrier by a bond or a linking group. Kits for conducting the methods of the present invention are also disclosed.

Abstract: The invention concerns a process for the preparation of hybridoma cells which secrete monoclonal antibodies specific for hirudin, the hybridoma cells themselves, the monoclonal antibodies specific for hirudin secreted by these hybridoma cells, derivatives thereof, and a process for the preparation of said antibodies and derivatives. These monoclonal anti-hirudin antibodies and their derivatives are useful for the determination of hirudin and as an antidote to hirudin. The invention also concerns test kits and pharmaceutical compositions comprising said monoclonal antibodies and/or derivatives.

Abstract: A method of assay for isotopically exchangeable analytes is disclosed. Analytes are labeled by enzymatic exchange of a hydrogen atom of the analyte and a deuterium or tritium atom. Preferably, analytes are labeled by reaction with an oxidant, a reducing agent which contains a deuterium or tritium atom, and an enzyme capable of catalyzing the reversible exchange of a hydrogen atom between the analyte, the oxidant, and the reducing agent. Kits for conveniently performing the assay methods are also disclosed.

Abstract: The present invention provides methods for the diagnosis of non-healing ulcers in humans. Provided are methods for detecting the presence of non-healing ulcers by assaying for certain cell adhesion-related proteins or their degradation products in ulcer exudate. The methods of the present invention are useful as an initial, quick and inexpensive screening process for a condition which is often misdiagnosed. It has been discovered that in non-healing ulcers there appear to be proteases which degrade cell adhesion-related proteins, e.g., fibronectin and vitronectin. Protein separation techniques, such as electrophoresis, may be used in combination with immunoassay techniques to isolate and identify these degradation products, as well as the cell adhesion-related proteins themselves.

Abstract: A process is disclosed for the enhancement of the chemiluminescence of enzyme-triggered 1,2-dioxetanes detectable within a sample. The process comprises first providing a solid support having sample disposed thereon and suitably treated with a solution including enzyme-triggered 1,2-dioxetanes. The solid support is next dried and optionally heated either simultaneously with drying or thereafter. The steps of drying and/or heating are conducted either prior to or simultaneously with detection.

Abstract: The invention relates to a new variety of retroviruses designated Immunodeficiency Virus Type II, HIV-II, samples of which have been deposited at CNCM as I-502 and I-532. It also concerns purified forms of the antigens which can be obtained from this virus, in particular from the gp 36 and gp 130-140 proteins. These various antigens are useful in medical diagnosis and kits, in particular by being placed in contact with serum of the patient to be diagnosed. Lastly, the invention relates to immunizing compositions, in particular containing at least one of glycoproteins gp 36 and gp 130-140.

Abstract: A method of preparing a dry-type analytical element for immunoassay having at least one water-permeable porous layer and containing a labeled antigen and an antibody to said labeled antigen and to an unlabeled antigen as the components participating in antigen-antibody reaction in said porous layer, which comprises applying or impregnating a first composition containing one of said labeled antigen and said antibody and thereafter applying or impregnating a second composition containing the other of said labeled antigen and said antibody dissolved or suspended in a solvent not dissolving substantially said labeled antigen or said antibody in the first composition onto said porous layer.

Abstract: Specific binding methods are used for diagnostic assays and purification separations whereby the specific binding capture reagent is prepared from copolymers having highly reactive carboxy groups. These groups are extended from the polymer surface with a linking group having from 8 to 50 atoms in the chain and two or more alkylene, arylene, alkylenearylene or arylenealkylene groups. To these reactive groups is attached a biologically active substance such as a protein or oligonucleotide which then participates in the diagnostic assays or purification separation methods.

Abstract: This invention provides a method as well as a kit for diagnosing Alzheimer's disease. The method comprises the steps of obtaining a non-neural tissue biopsy sample, contacting at least a portion of the sample with a quantity of antibodies capable of identifying .beta.AP, a .beta.-amyloid precursor protein fragment comprising .beta.AP, or a .beta.AP peptide fragment of about 8 or more amino acids sufficient to allow detection of said protein, protein fragment or peptide fragment, and monitoring the extent of the reaction between the sample and the antibodies. The kit comprises antibodies specific for .beta.-amyloid protein, or a .beta.-amyloid precursor protein fragment comprising .beta.-amyloid protein, or a peptide fragment of .beta.-amyloid protein of at least about eight amino acids, and a means for detecting the extent of the reaction of the antibodies with a non-neural tissue sample.

Abstract: Highly immunoreactive regions of gp41 of HIV-1, gp32 of HIV-2 and p24 of HIV-1 were identified using synthetic peptides. Superior immunoassay performance is obtained with these peptides linked to carrier proteins as compared to use of the free peptides. Additional natural and unnatural variants of these reactive regions to define a set of peptides that, as cysteine-linked peptide-protein conjugates, provide optimal immunoassay performance including high immunoreactivity with HIV antibody positive samples, low reactivity with negative samples, high discrimination between positives and negatives, and high specificity. These peptide conjugates further permit simultaneous detection of HIV-1 and HIV-2 antibodies, and make possible rapid and simple test formats that require no instrumentation for detection of these antibodies.

Abstract: A method and apparatus for calibrating or checking the calibration of vertical photometers. The invention may also provide easy and convenient assay results for diagnostic profiles. The invention comprises pre-dispensed amounts of a suitable reagent, chosen for the particular use, disposed in a vessel with an amount of a wetting agent or other means to yield a reproducible meniscus in the resulting control solution. The control solution is dried to leave a precise amount of dried reagent and other constituents in the vessel which can then be stored and distributed until subsequent use. The dried control solution can then be reconstituted to provide a standard having known absorbance and physical characteristics.

Abstract: The present invention relates to a highly sensitive diagnostic/prediagnostic test to identify persons at risk of a thrombotic event. Thrombotic events include myocardial infarction, deep venous thrombosis, pulmonary embolism, thromboembolic stroke pulmonary embolism deep venous and cardiovascular disease. The test is based on the early detection of elevated levels of resting platelet surface thrombospondin. The present invention also includes methods of determining the presence of thrombospondin on the surface TSP receptors of resting platelets in a biological sample. An anti-thrombospondin monoclonal antibody which is specific for thrombospondin on resting platelets is also disclosed. A diagnostic test in the form of a test kit for the determination of thrombospondin levels in a patient sample, and also for the prediagnosis of persons at risk for thrombotic events, is also described.

Abstract: The present invention provides compounds of the general formula: ##STR1## wherein R is a trifluoromethyl radical or a cyano group. The present invention also provides processes for the preparation of these compounds, as well as reagents containing them. The present invention is also concerned with the use of these compounds as .beta.-galactosidase substrates, especially in a CEDIA system.

Abstract: A method for the visualization of serotonergic cells in the dorsal raphe of living nonhuman vertebrates by pretreatment with L-tryptophan significantly less than one hour prior to sacrifice reveals numerous structures and cell types hitherto unidentified when combined with immunocytochemistry, immunofluorescence, or serotonin tagged autoradiography in the light microscope.

Abstract: A method disclosed for studying the interaction in solution of two molecules of the type such as a ligand and a receptor that are capable of reacting or binding with each other. The method comprises preparing an aliquot of a solution containing the first of the molecules. The second of the molecules is then added to the aliquot. A fluorescently labeled molecule is added to the aliquot, wherein the fluorescently labeled molecule is also capable of reacting or binding with the second of the molecules. A porous matrix that is optically transparent is immersed into the aliquot containing the two molecules being studied and the fluorescently labeled molecule, wherein the second molecule and any fluorescently labeled molecule bound thereto is sterically hindered from permeating the porous, optically transparent matrix, while any unbound fluorescently labeled molecule permeates the matrix.

Abstract: An indicator reagent, assay method and test kit for determining the presence or amount of an analyte in a test sample, in which the indicator reagent is formed by attaching an organic polymer latex particle, preferably a colored particle, to a specific binding member. The specific binding member can be adsorbed onto or covalently bound to the organic polymer latex particles. The organic polymer latex particles are readily detected by direct visual observation or can be detected and/or measured by appropriate instrumentation.

Abstract: An improved fiber optic sensor, sensing apparatus, and methods for making optical detections are provided. The fiber optic sensor employs a fiber optic strand to convey light energy, an immobilized polymeric reaction matrix, and at least one controlled release polymeric carrier within said reaction matrix comprising a controlled release polymer material and a releasable reagent formulation able to react with the analyte of interest. The optic sensors and sensor construction have been demonstrated to be both functionally useful and long serving in duration.

Abstract: The present invention provides an immunological process for the determination of the luteinizing hormone (LH), wherein at least one monoclonal antibody is used which is directed against LH and cross-reacts with other glycoprotein hormones to an extent of less than 3%.The present invention also provides a reagent for the determination of the luteinizing hormone, wherein it contains at least one monoclonal antibody which is directed against LH and cross-reacts with other glycoprotein hormones to an extent of less than 3%.Furthermore, the present invention provides a monoclonal antibody against the luteinizing hormone and a process and a hybridoma cell line for producing it.

Abstract: The present invention is intended to provide an EIA method utilizing bioluminescence using a firefly luciferase. The EIA method of the present invention is characterized by using an ATP-generating enzyme as a labeling enzyme, subjecting ATP generated to bioluminescence by the use of the firefly luciferase, and measuring the quantity of light emitted. Acetate kinase is a preferred enzyme used in the method.

Abstract: Hybridomas producing antibodies having specific binding affinity against Pneumocystis carinii have been obtained and a method and kit for detecting P. carinii infection in humans have been described.

Abstract: A method and apparatus for performing determinations of immune reactants (e.g., antigens, antibodies) in bodily fluids utilize multiple test units having respective elongated rods with transversely-expanded polymer tips at their distal ends. The tip surfaces contain microgrooves and are coated with respective immune reactants (e.g., allergens) of the type which react in a known manner with respective allergen-specific or allergen-binding antibodies in human serum. The supporting strip for the test units has through-holes which frictionally or adhesively engage the proximal ends of the test unit rods with a spacing that permits all of the supported test units to be simultaneously inserted into a reaction vessel permitting simultaneous determination of reactants and degrees thereof against multiple immune reactants of varying kinds (i.e., allergens, antigens, antibodies) in a common sample of body fluid (i.e., serum, plasma, whole blood, etc.).

Abstract: A method of immunologically staining a formalin-fixed tissue preparation, which comprises (a) subjecting a formalin-fixed tissue preparation to microwave energy while the tissue preparation is submersed in water for a time sufficient to increase immunostaining efficiency; (b) removing the tissue preparation from the water and cooling; and (c) contacting the tissue preparation with an immunological staining reagent.

Abstract: The present invention provides an improved assay for measuring thyroxine uptake by thyroxine binding globulin in which thyroxine binding globulin (TBG) activity is measured directly. The method comprises combining a sample in an aqueous solution with an enzyme donor (ED) conjugated to an analogue of polyiodothyronine that competes with thyroxine for thyroxine binding globulin binding sites. An enzyme acceptor (EA) characterized by providing a modulated enzyme activity in relation to the amount of TBG activity is combined with an enzyme donor and sample in an aqueous solution. The amount of enzyme activity in comparison to a control solution having a known amount of available TBG binding sites is determined.

Abstract: A simultaneous dual analyte assay for determining the fertile period of the human menstrual cycle. The assay utilizes a capture reaction component consisting of P-3-G immobilized on a microporous membrane, a blocking reaction component consisting of anti E.sub.1 -3-G antibody, a labelled reaction component consisting of gold particle labelled anti E.sub.1 -3-G antibody, and an ambifunctional reaction component consisting of a hybrid immunoreactive substance having an anti P-3-G antibody binding site and a plurality of E.sub.1 -3-G determinant binding sites. An aqueous sample containing P-3-G and E.sub.1 -3-G is contacted with the components and the assay is calibrated to provide a positive assay result only when the concentration of P-3-G in the sample is less than a predetermined concentration and the concentration of E.sub.

Abstract: Processes for preparing stable natural matrices for prostrate specific antigen (PSA) are disclosed. Biological carrier fluids for PSA obtained from a suitable mammal are modified to inhibit the activity of components of the biological fluids destabilizing to PSA. The stable natural matrices, prepared in accordance with the present invention, are useful in the measurement of PSA in a sample by means of an immunoassay.

Abstract: Enzymatic immunoassay for estimating the concentration of antigen or antibody comprising bringing an antigen-antibody complex, which is labelled by an enzyme and is present heterogeneously in a solution, into contact with a substrate where pH of the solution is so adjusted as to be suitable for the enzyme to be activated and also for measuring the fluorescence of the substrate, measuring the time-variation of fluorescent intensity of the substrate produced by the enzyme reaction, and estimating the concentration of the antigen or the antibody from the slope of the substantially linear portion, on a characteristic curve representing variation of the fluorescence intensity with the time.Fluorescence is measured while magnetic beads with antigen-antibody complex attached are oscillated at a specific frequency.

Abstract: An immunoassay method for the detection or quantitation of an analyte suspected of being in a solution comprising: (a) combining said specimen, a first binding component, insoluble particles, and second binding component labelled with a signal generating material in a solid phase retention and separation apparatus having a sufficient pore size such that said particles are trapped within said filter yet permitting rapid passage of fluid therethrough in such a manner that an immunological reaction occurs if analyte is present in said specimen, resulting in the formation of an immunocomplex of insolubilized first binding component:analyte:second labelled binding component on or within said filter means; (b) separating bound from unbound material; and (c) determining the presence and/or amount of signal produced which is correlative with the amount of analyte present in the solution.

Abstract: The invention relates to an assay for determining an analyte in a fluid sample. Three receptors are used, with formation of a quaternary or four member complex. One of the receptors is bound to a solid phase, and binds to complexes of another receptor and the analyte. A third receptor is labelled, and it, too, binds analyte. The invention also involves the use of a displacement solution to wash fluid sample from solid phase after the first portion of the quaternary complex forms, i.e., prior to binding with the labelled receptor.

Abstract: Methods and compositions are provided for concentrating particles in a minute area on a solid surface. The method permits the detection of small amounts of analytes by providing for an observable signal in relation to the concentration of particles in the area.