Anti-La (SS-B) DIASTAT®

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The La (SS-B) antigen is an RNA-protein complex and antibodies against it are found in about 40% of patients with primary Sjögren’s syndrome and in 15% of patients with systemic lupus erythematosus (SLE). Anti-La (SS-B) antibodies have also been detected in patients with systemic sclerosis and neonatal lupus erythematosus. In patients with Sjögrens’s syndrome and SLE the antibodies commonly occur together with Ro (SS-A).


Product code
FALA 200
Format
ELISA
Tests
96 wells
Calculation
Quantitative and qualitative
Antigen
Purified La (SS-B) antigen
Units
U/mL
Calibrators
5
Range
0-100 U/mL
Incubation time
60+30+30 min
Detection system
ALP/PMP (550 nm)
Availability
CE marked. For sale in US

Intended use

The DIASTAT® anti-La (SS-B or La) test is a quantitative/qualitative enzyme-linked immunosorbent assay (ELISA) for the detection of autoantibodies specific for La (SS-B) antigen in human serum or EDTA, lithium heparin, citrated plasma. It is intended to aid in the diagnosis of systemic rheumatic diseases, particularly Sjögren's syndrome and is not definitive in isolation. Autoantibody levels represent one parameter in a multicriterion diagnostic process.

 

Background

Systemic rheumatic diseases are autoimmune disorders such as systemic lupus erythematosus (SLE), polymyositis, Sjögren's syndrome, scleroderma and mixed connective tissue disease. A general feature of systemic rheumatic diseases is the presence of circulating antibodies to a variety of cellular antigens. The detection and serological characterisation of specific autoantibodies plays an important role in the differential diagnosis of these diseases.

The La (SS-B) antigen is an RNA-protein complex; antibodies against it are found in Sjögren's syndrome (40%) and SLE (15%). Anti-La (SS-B) antibodies have also been detected in patients with systemic sclerosis and neonatal lupus erythematosus. There is evidence associating these antibodies to particular clinical characteristics, and the observation that patients may have autoantibodies before the full onset of disease confirms the need for an accurate and easy-to-use test.

Technical information

The wells of the microtitre strips are coated with affinity-purified La (SS-B) antigen. During the first incubation, specific autoantibodies in diluted serum or plasma bind to the antigen-coated surface. The wells are then washed to remove unbound components. In the second incubation, the Conjugate, enzyme-labelled antibodies to human IgG, binds any surface-bound autoantibodies. After further washing, specific autoantibodies are traced by incubation with the Substrate. Addition of Stop Solution terminates the reaction, resulting in a coloured end-product. The amount of Conjugate bound is measured in absorbance units. In the qualitative protocol, the amount of Conjugate bound by the sample is compared with that bound by the Reference Control. In the quantitative protocol, the concentration of anti-La (SS-B) autoantibody can be estimated by interpolation from a dose?response curve based on Standards.