RSR Limited for Autoimmune Diagnostics

COMPLETE PRODUCT LISTING

ADRENAL AUTOIMMUNITY

Autoimmune destruction of the adrenal cortex is the most common cause of Addison's disease. The adrenal specific enzyme steroid 21-hydroxylase (21-OH) is a major adrenal autoantigen and autoantibodies to 21-OH are important markers of autoimmune adrenal disease. This is the case whether the disease presents as isolated Addison's disease or as part of the autoimmune polyglandular syndromes (APS) type I or type II.

21-OHAb RIA Kit (50 or 100 tubes)Technical information
RSR's assay for 21-OH autoantibodies is based on highly purified, ¹²⁵I-labelled, recombinant human 21-OH. In the assay, test serum samples are first incubated with ¹²⁵I-labelled 21-OH. This is followed by the addition of solid phase protein A to precipitate labelled 21-OH-21-OH antibody complexes. After centrifugation, the precipitates are counted for ¹²⁵I and the amount of radioactivity in the precipitates is proportional to the concentration of 21-OH antibody in the test sample.

ISLET CELL AUTOIMMUNITY

Type 1 diabetes mellitus is characterised by islet cell autoimmunity and several different islet cell autoantibodies are important in the diagnosis and management of this disease. These include autoantibodies to glutamic acid decarboxylase (GAD), to IA2 and to insulin. A combination of these assays allows assessment of the risk of an individual developing type 1 diabetes.

GADAb ELISA Kit (96 wells)Technical information
RSR has developed a new highly sensitive and specific GADAb ELISA. ELISA plate wells are coated with GAD and after incubation with test sera, antibodies monovalently bound to the coated wells are detected by addition of GAD-biotin. The biotinylated antigen binds to the free second antigen binding sites of bound autoantibodies. Streptavidin peroxidase and the substrate TMB are then used to quantitate bound biotinylated antigen with the final absorbance reading being proportional to the amount of autoantibody in the test sample

IA-2Ab ELISA Kit (96 wells)Technical information
RSR has also developed a new highly sensitive and specific IA-2Ab ELISA using the same principle as the RSR GADAb ELISA. ELISA plate wells are coated with IA-2 and after incubation with test sera, antibodies monovalently bound to the coated wells are detected by addition of IA-2-biotin. The biotinylated antigen binds to the free second antigen binding sites of bound autoantibodies. Streptavidin peroxidase and the substrate TMB are then used to quantitate bound biotinylated antigen with the final absorbance reading being proportional to the amount of autoantibody in the test sample

2 Screen ICA ELISA Kit (96 wells)Technical information
In addition to GADAb and IA-2Ab ELISAs RSR has developed a highly sensitive and specific 2 Screen GAD/IA-2 Ab ICA ELISA which detects both GADAb and IA-2Ab simultaneously. ELISA plate wells are coated with a mixture of GAD and IA-2 and after incubation with test sera, antibody monovalently bound to the coated wells is detected by addition of GAD/IA-2-biotin. The biotinylated antigens bind to the free second antigen binding sites of the divalent autoantibodies. Streptavidin peroxidase and the substrate TMB are then used to quantitate bound biotinylated antigen with the final absorbance reading being proportional to the amount of autoantibodies in the test sample.

GADAb RIA Kit (50 or 100 tubes)Technical information
In RSR's GAD autoantibody assay, test serum samples are incubated, first with ¹²⁵I-labelled human recombinant GAD 65. This is followed by addition of solid phase protein A to precipitate the labelled GAD-GAD antibody complexes. After centrifugation, the precipitates are counted for ¹²⁵I and the amount of radioactivity in the precipitate is proportional to the concentration of GAD antibody in the test sample.

IA-2Ab RIA Kit (50 or 100 tubes)Technical information
In RSR's IA-2Ab assay, test serum samples are incubated first with ¹²⁵I-labelled human recombinant IA-2. This is followed by addition of solid phase protein A to precipitate the labelled IA-2-IA-2 antibody complexes. After centrifugation, the precipitates are counted for ¹²⁵I and the amount of radioactivity in the precipitate is proportional to the concentration of IA-2 antibody in the test sample.

IAA RIA Kit (50 or 100 tubes)Technical information
In RSR's Insulin antibody (IAA) assay, test serum samples are incubated first with ¹²⁵I-(A14)-monoiodinated insulin. This is followed by addition of anti-human IgG to precipitate any labelled Insulin-Insulin antibody complexes which have formed. After centrifugation, the precipitates are counted for ¹²⁵I and the amount of radioactivity in the precipitate is proportional to the concentration of IAA in the test sample.

NEUROMUSCULAR AUTOIMMUNITY

Muscle weakness in myasthenia gravis (MG) is due to autoantibodies to the acetylcholine receptor (AChR) and the presence of acetylcholine receptor antibodies (AChRAb) in patient sera is diagnostic for MG. Lambert-Eaton myasthenic syndrome (LEMS) is a different form of MG (often associated with small cell lung cancer) in which autoantibodies are directed against voltage gated calcium channels (VGCCs).

AChRAb RIA Kit (25, 50 or 100 tubes)Technical information
A carefully balanced mixture of detergent solubilised foetal and adult forms of the AChR is the optimum preparation for AChRAb assays. Consequently a mixture of these 2 receptors labelled with ¹²⁵I-labelled alpha bungarotoxin provides the basis for RSR's AChRAb assay kit.
In the assay, labelled receptors are incubated with test sera and any resulting complex of labelled receptor and receptor antibody immunoprecipitated with anti-human IgG. The higher the concentration of autoantibody, the greater the amount of radioactivity precipitated. The kit is easy to use and provides a specific and sensitive assay, being able to detect AChRAb in 80-90% of patients with myasthenia gravis.

AChRAb ELISA Kit (coated on ELISA plate wells)Technical information
The AChRAb ELISA depends on the ability of AChRAb in human serum to bind to similar sites on the AChR as various monoclonal antibodies such as MAb1 (coated on ELISA plate wells) and/or MAb2 and/or MAb3 (which are both labelled with biotin). In the absence of AChRAb a complex is formed between MAb1 coated on the plate wells, the AChR and MAb2 biotin and MAb3 biotin. MAb2 and MAb3 biotin bound are then detected by addition of streptavidin peroxidase (SAPOD), substrate (TMB) and stop solution. In the presence of AChRAb the formation of the MAb-1-AChR-MAb2/MAb3 biotin complex is inhibited, resulting in less SAPOD being bound and a reduction in final absorbance at 450nm. The higher the concentration of AChRAb in the test serum, the greater the inhibition of MAb biotin binding.

LEMS RIA Kit (12 or 25 tube kits) Technical information
The assay depends on the use of detergent solubilised P-type VGCCs extracted from rabbit cerebellum and labelled with ¹²⁵I-labelled w-conotoxin MVIIC. The ¹²⁵I-labelled P-type VGCCs are then incubated with test sera and the resulting complexes immunoprecipitated with anti-human IgG. The higher the concentration of autoantibody, the greater the amount of radioactivity precipitated. Non-specific binding in the assay is determined using a preparation of VGCCs supplied in the kit which have been labelled with ¹²⁵I-conotoxin in the presence of an excess of unlabelled conotoxin.

THYROID AUTOIMMUNITY

There are 3 different autoantibodies important in the diagnosis and management of autoimmune thyroid disease:
a) TSH receptor autoantibodies (TRAb) - These autoantibodies are responsible for a common form of thyroid overactivity known as Graves' disease and in this condition the antibodies bind to the receptor for thyroid stimulating hormone (TSH) and mimic the effects of TSH in an uncontrolled way. Clinically, the measurement of TRAb is important to distinguish Graves' disease from other forms of thyroid dysfunction such as toxic nodular goitre and to monitor treatment of Graves' disease. TRAb measurement is also indicated for pregnant patients with a history of thyroid disease in order to assess the risk of the neonate developing thyroid disease.

TRAb Coated Tube RIA Kit (60 or 100 tubes) Technical information
TSH receptor autoantibodies in patients' sera are allowed to interact with TSH receptor coated onto plastic tubes. Bound TRAb are detected by their ability to inhibit the binding of ¹²⁵I-labelled TSH to the receptor coated tubes and TRAb levels are read off a standard curve or expressed as an inhibition index.

TRAb RIA Kit (50 or 100 tubes) Technical information
TRAb inhibit the binding of ¹²⁵I-labelled TSH to detergent solubilised TSH receptors in a dose dependent way and bound and free labelled TSH separated by PEG precipitation. TRAb levels are read off a standard curve or expressed as an inhibition index.

TRAb ELISA Kit (96 wells)Technical information
TSH receptor autoantibodies in patients' sera are allowed to interact with TSH receptor coated onto ELISA plate wells. Bound TRAb are detected by their ability to inhibit the binding of TSH (in the form of TSH-Biotin) to the receptor coated wells. The amount of TSH-Biotin bound is then monitored by addition of streptavidin peroxidase and the peroxidase substrate tetramethyl benzidine. TRAb levels are expressed as an inhibition of TSH binding index or read off a standard curve. A new version of the TRAb ELISA uses competition between patient sera TRAb and a thyroid stimulating human monoclonal antibody (M22) for TSH receptor coated onto ELISA plate wells. This third generation TRAb ELISA displays excellent sensitivity. Furthermore another version of the TRAb ELISA assay is now available, RSR’s Fast TRAb ELISA. In this assay M22 is coupled directly to peroxidase allowing fewer steps and shorter assay time.

(b & c) Autoantibodies to thyroid peroxidase (TPO) and to thyroglobulin (Tg) - Graves' disease is only one form of autoimmune thyroid disease and a similar proportion (about 1%) of the world's population suffers from thyroid under-activity associated with thyroid autoimmunity. In this disease (a common form of which is Hashimoto's disease), thyroid destruction is associated with the presence of autoantibodies to two other thyroid proteins - thyroid peroxidase (TPO) and thyroglobulin (Tg). RSR produces several different isotopic and non-isotopic kits for measuring autoantibodies to TPO and to Tg; they all show high sensitivity, good precision and no cross-reactivity with other autoantibodies.

TgAb Coated Tube RIA Kit (100 tubes) Technical information
The TgAbCT kit uses tubes coated with Tg antibody and the autoantibodies in patient serum samples inhibit the binding of ¹²⁵I-labelled Tg to the coated tube. The assay procedure is simple and involves only one incubation of undiluted serum and tracer in the coated tubes.

TgAb Direct RIA Kit (50, 100 or 500 tubes) Technical information
This method is based on the direct interaction between the autoantibodies and ¹²⁵I-labelled Tg and is one of a generation of quantitative assays which have the following features: high sensitivity, flexible design, high precision, easy handling, high specificity, no interference from other antibodies. Studies with different groups of patients show that the direct assays are of greater diagnostic value than less sensitive methods.

TgAb Magnetic RIA Kit (100 or 200 tubes) Technical information
This method is based on the direct interaction between the autoantibodies and ¹²⁵I-labelled Tg, with separation of the labelled complex using protein A coupled to a magnetic solid phase. The assay offers a high sensitivity, specificity and precision along with simple use and short incubation times.

TgAb ELISA Kit (96 wells) Technical information
The Tg autoantibody ELISA kit provides a convenient and automatable method of quantitating Tg autoantibodies in patients' serum samples. The assay is based on an easy to use and flexible, break-apart well system employing wells coated with purified thyroglobulin. Patients' serum (or plasma) samples are assayed at a dilution of 1 in 20 and the same diluted sample can be used for both Tg autoantibody and TPO autoantibody ELISAs. Autoantibody binding to the Tg coated wells is detected using protein A conjugated to alkaline phosphatase and total assay time is about 90 minutes.

TPOAb Coated Tube RIA Kit (100 tubes) Technical information
The TPOAbCT kit uses tubes coated with an antibody to TPO and the autoantibodies in patient serum samples inhibit the binding of ¹²⁵I-labelled TPO to the coated tube. The assay procedure is simple and involves only one incubation of undiluted serum and tracer in the coated tubes.

TPOAb Direct RIA Kit (50, 100 or 500 tubes) Technical information
This method is based on the direct interaction between the autoantibodies and ¹²⁵I-labelled TPO and one of a generation of quantitative assays which have the following features: high sensitivity, flexible design, high precision, easy handling, high specificity, no interference from other antibodies. Studies with different groups of patients show that the direct assays are of greater diagnostic value than less sensitive methods.

TPOAb Magnetic RIA Kit (100 or 200 tubes) Technical information
This method is based on the direct interaction between the autoantibodies and ¹²⁵I-labelled TPO, with separation of the labelled complex using protein A coupled to a magnetic solid phase. The assay offers a high sensitivity, specificity and precision along with simple use and short incubation times.

TPOAb ELISA Kit (96 wells) Technical information
The TPO autoantibody ELISA kit provides a convenient and automatable method of quantitating TPO autoantibodies in patients' serum samples. The assay is based on an easy to use and flexible, break-apart well system employing wells coated with purified TPO. Patients' serum (or plasma) samples are assayed at a dilution of 1 in 20 and the same diluted sample can be used for both TPO autoantibody and Tg autoantibody ELISAs. Autoantibody binding to the TPO coated wells is detected using protein A conjugated to alkaline phosphate and total assay time is about 90 minutes.

THYROID CANCER

Thyroid cancer is usually treated by surgical removal of malignant and normal thyroid tissue followed by destruction of any remaining thyroid tissue with radioactive iodine (given orally). In the absence of any thyroid tissue, little or no thyroglobulin (Tg) is present in patients' blood samples and consequently, measurement of thyroglobulin levels is valuable in assessing the effectiveness of treatment. Also, any recurrence of malignant thyroid tissue results in increases in levels of thyroglobulin in the patient's blood.

Tg IRMA Kit (50 or 100 tubes) Technical information
The Tg IRMA uses two monoclonal Tg antibodies which recognise different epitopes. One antibody is coated onto plastic tubes and the other is labelled with ¹²⁵I. Test samples are incubated in the coated tubes with labelled antibody and a sandwich is formed between Tg in the test sample, the labelled antibody and the antibody coated onto the plastic tube. After a wash step, the tubes are counted and the radioactivity bound is proportional to the Tg concentration in the sample. The method is sensitive, being able to detect as little as 0.6 ng/mL of Tg and has a measuring range of up to 250 ng/mL. Interference from Tg autoantibodies is minimal as assessed by recovery tests.

Tg ELISA Kit (96 wells) Technical information
Tg is measured in an ELISA using two monoclonal Tg antibodies which recognise different epitopes. One antibody is coated onto ELISA plate wells and test samples are incubated in the wells for 2 hours with shaking. After a washing step, the second antibody which is conjugated to horseradish peroxidase is added, and a sandwich-type complex becomes bound to the wells during a second overnight incubation. After a further washing step, substrate is introduced and the final absorbance at 450 nm is directly proportional to the Tg concentration in the sample. The method is highly sensitive being able to detect as little as 0.03 ng/mL of Tg.