Abstract: A method for analyzing protein(s) in a sample using an immunoassay kit includes creating protein-reducing and/or protein-denaturing conditions by contacting the sample with a reducing and/or denaturing agent provided in the immunoassay kit, to provide a partially or fully denatured protein population. One or both of a presence and an amount of one or more protein-associated analytes are determined under the created protein-reducing and/or protein-denaturing conditions by contacting the partially or fully denatured protein population with one or more specific antibodies or binding fragments thereof provided in the immunoassay kit. The one or more specific antibodies or binding fragments thereof include one or more chemically-introduced non-disulfide cross-links between at least one heavy chain or binding fragment thereof and at least one light chain or binding fragment thereof.

Abstract: This invention provides a method of identifying or characterising an immune response in a subject comprising: (a) contacting a sample containing immunoglobulins from the subject with at least one antigen immobilised on a support; (b) washing unbound, non-antigen specific immunoglobulins from the support to leave antigen-specific immunoglobulins bound to the antigen on the support; (c) optionally eluting the antigen-specific immunoglobulins from the antigen on the support; and (d) subjecting the antigen-specific immunoglobulins to mass spectrometry to identify two or more different antigen specific immunoglobulin classes, subclasses and/or light chain types.

Abstract: The Invention provides a method of immunopurifying and characterising an analyte from a sample comprising: (i) providing a predetermined amount of a control substance bound to a substrate via a linkage cleavable by acidic pH and/or reducing agents and optionally additional analyte specific antibodies or fragments thereof bound to a substrate, wherein the control substance is specific for the analyte or is not specific for the analyte; (ii) allowing analyte when present in the sample to bind to the control substance or said optional additional analyte-specific antibodies or fragments, wherein the control substance bound to the substrate (i) may be provided after contacting the analyte with the optional additional analyte-specific antibodies (ii); (iii) washing unbound material away from the substrate; (iv) acid eluting the analyte bound thereto, from at least one substrate; (v) performing mass spectrometry to identify two or more peaks, at least one peak of which is associated with the presence of the analyte

Abstract: The application provides a method of identifying or monitoring a plasma cell associated disease, comprising purifying immunoglobulin free light chains (FLCs) from a sample from a subject with anti-FLC specific antibodies or fragments thereof and subjecting the purified sample to a mass spectrometry technique to identify the presence of one or more peaks corresponding to one or more monoclonal FLCs in the sample.

Abstract: Method of Detecting or Monitoring Minimal Residual Disease The application describes a method of identifying minimal residual disease (MRD) in a monoclonal gammopathy patient, comprising detecting the presence or absence of a monoclonal free light chain (FLC) in a sample from the patient by mass spectrometry (MS).

Abstract: An elution buffer for eluting one or more predetermined analytes from one or more analyte-specific antibodies or fragments thereof or for eluting one or more predetermined antibodies or fragments from a target antigen, wherein: the elution buffer has a pH of 1 to 5; and the elution buffer comprises a predetermined amount of an acid stable mass spectrometry ionisation control protein. The use of the elution buffer in the detection and quantifying of analytes, for example by mass spectrometry is also described.

Abstract: The invention provides a method of quantifying the amount of kappa or lambda immunoglobulin light chain in a sample from a subject comprising: i. providing a sample from a subject; ii. mixing the sample with a predetermined amount of lambda light chain calibrator or kappa light chain calibrator to form a mixture; iii. performing mass spectrometry on the mixture; and iv quantifying one or both of a) the amount of lambda light chain in the sample by comparing the relative amount of lambda light chain in the mixture as determined by the mass spectrometry to the relative amount of calibrator kappa light chain in the mixture as determined by mass spectrometry; and/or b) the amount of kappa light chain in the sample by comparing the relative amount of kappa light chain in the mixture as determined by mass spectrometry to the relative amount of calibrator lambda light chain in the mixture as determined by mass spectrometry, most typically MALDI-TOF spectrometry or liquid chromatography-mass spectrometry.

Abstract: The application provides a method of identifying or monitoring a plasma cell associated disease, comprising purifying immunoglobulin free light chains (FLCs) from a sample from a subject with anti-FLC specific antibodies or fragments thereof and subjecting the purified sample to a mass spectrometry technique to identify the presence of one or more peaks corresponding to one or more monoclonal FLCs in the sample.

Abstract: An anti-immunoglobulin specific antibody (or fragment thereof), characterised that the antibody or fragment thereof comprises one or more non-disulphide cross-links between at least one heavy chain or fragment thereof and at least one light chain or fragment thereof of the antibody or fragment thereof. A method purifying an anti-immunoglobulin specific antibody (or fragment thereof), characterised that the antibody or fragment thereof comprises one or more non-disulphide cross-links between at least one heavy chain or fragment thereof and at least one light chain or fragment thereof of the antibody or fragment thereof.

Abstract: The invention provides an immunoassay kit providing an immunoassay kit comprising one or more analyte specific antibodies or fragments thereof, characterised that the antibody or fragment thereof comprises one or more non-disulphide cross-links between at least one heavy chain or fragment thereof and at least one light chain or fragment thereof of the analyte- specific antibodies or fragments thereof.