SS-B Ab ELISA Kit (Sjögren Syndrome Type B)

Full Name: SS-B Ab ELISA Kit (Sjögren Syndrome Type B)
Reactivity: Human
Sample Type: Serum, Plasma
Sensitivity: 1.0 U/ml

BACKGROUND

Sjögren’s syndrome is an autoimmune condition characterized by chronic dryness of the eyes and mouth due to dysfunction of the salivary and lacrimal glands. There are two types – primary Sjögren’s syndrome (SS-A) occurs by itself while secondary Sjögren’s (SS-B) happens in the presence of other autoimmune diseases like rheumatoid arthritis or systemic lupus erythematosus.

In Sjögren’s syndrome, lymphocytic infiltration of the exocrine glands occurs, causing impaired secretory function. This is mediated in part by autoantibodies directed against intracellular antigens. Anti-SS-A (Ro) and anti-SS-B (La) are the classic Sjögren’s autoantibodies. SS-B antibodies target the La antigen, a 48kDa RNA-binding nuclear protein involved in RNA polymerase III transcription termination. The La protein undergoes apoptotic modifications in salivary gland epithelial cells, leading to autoantibody production.

SS-B autoantibodies are found in approximately half of Sjögren’s patients. They are associated more with primary than secondary Sjögren’s syndrome. Presence of anti-SS-B correlates with higher gammaglobulin levels, more lymphocytic infiltration on minor salivary gland biopsy, and abnormalities on ocular staining. SS-B antibodies can cross the placenta and cause neonatal lupus syndromes.

INTENDED USE

Human SS-B Ab ELISA kit is designed for measuring in-vitro quantitative levels of IgG auto-antibodies to Sjögren syndrome type B (SS-B antibody, SS-B/La, SS-B Ab, anti-SSB) in human plasma or serum. This assay has a minimum analytical sensitivity limit of 1.0 U/ml.

CONTENT

All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

Divisible Microplate: Consisting of 12 modules of 8 wells, highly purified SS-B antibodies bound to microwells.
Calibrators (A-F): Concentrations 0, 12.5, 25, 50, 100, 200 U/ml, made up from anti SS-B antibodies.
Controls Positive and Control Negative: Containing human SS-B antibody.
Sample Buffer P (5x).
Enzyme Conjugate: Contains anti-human IgG antibodies, HRP labelled.
TMB Substrate.
Stop Solution: Contains acid.
Wash Buffer (50x Concentrated).
Instruction Manual.
Certificate of Analysis.

SENSITIVITY

The minimum detection sensitivity level of Sjögren syndrome type B (anti-SSB, SS-B Ab, SS-B/La) IgG autoantibodies using current SS-B antibody ELISA kit was 1.0 U/ml. The dynamic range for this assay is 12.5 – 200.0 U/ml.

ASSAY CHARACTERISTICS

– Limit Of Detection (LOD): 1 U/ml.
– Linearity: 97 – 107%
– Intra-Assay Precision: 5.2 – 5.8%
– Inter-Assay Precision: 4.1 – 11.0%
– Measuring Range: 0 – 200 U/ml
– Results Interpretation: Negative: < 15 U/ml, Borderline 15-25 U/ml, Positive: ≥ 25 U/ml.
– Expected Values: Cut-off 25 U/ml.
– Interference: None.
– Clinical Diagnosis: Sensitivity (61.4%), Specificity (95.8%), Overall agreement (83.7%).

REFERENCES

Antibodies against SS-B/La and SS-A/Ro antigens in patients with primary Sjögren’s syndrome. Scand J Rheumatol Suppl. (1986) 61: 93-7. Hansen B. and Manthorpe R.
Estimation of amounts of anti-La(SS-B) antibody directed against immunodominant epitopes of the La(SS-B) autoantigen. Clin Exp Immunol. (1991) 85 (3): 402-6. Gordon T.P., et al.
SS-B/La antigen purification, and ELISA detection of anti-SS-B/La antibodies in sera from patients with inflammatory connective tissue diseases. Allergy. (1988) 43 (8): 577-85. Hansen B., et al.
Autoepitopes reactive with anti-SS-B/La. J Autoimmun. (1989) 2 (4): 345-51. Whittingham S., et al.

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