Welcome to RSR Limited for diagnostics. Our services include the manufacture of medical in vitro diagnostic devices, production of reagents and kits for the test and diagnosis of autoimmune diseases.

COMPLETE PRODUCT LISTING - KITS & REAGENTS
KITS -
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.
 
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 IA-2 and to insulin. A combination of these assays allows assessment of the risk of an individual developing type 1 diabetes.
 
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.
 
RSR has also developed a new highly sensitive and specific IA-2 Ab 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.
 
In addition to GADAb and IA-2 Ab ELISAs RSR has developed a highly sensitive and specific 2 Screen GAD/IA-2 Ab ICA ELISA which detects both GADAb and IA-2 Ab 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.
 
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.
 
NEUROIMMUNOLOGY
Muscle weakness in myasthenia gravis (MG) is due to autoantibodies to the acetylcholine receptor (AChR) and the presence of acetylcholine receptor antibodies (AChR Ab) in patient sera is diagnostic for MG. The presence of autoantibodies to aquaporin-4 (AQP4) is diagnostic for Neuromyelitis optica (NMO), an immune-mediated neurological disease that affects the spinal cord and optic nerves. 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).
 
A carefully balanced mixture of detergent solubilised foetal and adult forms of the AChR is the optimum preparation for AChR Ab assays. Consequently a mixture of these 2 receptors labelled with 125I-labelled alpha bungarotoxin provides the basis for RSR's AChR Ab 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 AChR Ab in 80-90% of patients with myasthenia gravis.
 
The AChR Ab ELISA depends on the ability of AChR Ab 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 AChR Ab 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 AChR Ab 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 AChR Ab in the test serum, the greater the inhibition of MAb biotin binding.
 
The AQP4 Ab ELISA depends on the ability of AQP4 antibodies in human serum to bind to AQP4 coated onto ELISA plate wells. Bound antibodies are detected by adding biotinylated AQP4 which, due to the divalent nature of antibodies can interact with bound AQP4 antibodies. The amount of biotinylated AQP4 bound is then determined by addition of streptavidin peroxidase (SA-POD), substrate (TMB) and stop solution. The higher the concentration of antibody in the test serum, the higher the absorbance. The kit is easy to use and provides a specific and sensitive assay, being able to detect AQP4 Ab in about 90% of patients with Neuromyelitis optica.
 
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.

 
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 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.
 
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.
 
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.
 
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.
 
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.
 
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.
 
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.
 
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.

REAGENTS-

RSR reagents are available to assist you with your research or manufacturing:

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