Anti-Single Stranded DNA Antibody (ss-DNA) ELISA Kit

Short Description:

Anti-ssDNA (anti-single-stranded DNA antibody) is a subtype of anti-DNA antibodies, generally considered to have lower clinical significance and diagnostic importance compared to anti-dsDNA (anti-double-stranded DNA antibody). DNA, as a large molecular complex, consists of two nucleotide chains twisted into a double helix structure. When subjected to heat, the hydrogen bonds between complementary bases break, leading to DNA denaturation and the formation of ssDNA (single-stranded DNA). The primary reaction sites for anti-ssDNA are the purine and pyrimidine bases exposed on the ssDNA strand.

Notably, the detection results of anti-ssDNA lack disease specificity. While it shows a high positivity rate (50%~60%) in patients with systemic lupus erythematosus (SLE), it can also be detected in 10%~70% of cases with other rheumatic diseases, including mixed connective tissue disease (MCTD), drug-induced lupus, scleroderma, dermatomyositis, Sjögren’s syndrome, and rheumatoid arthritis. However, even in scenarios where anti-ssDNA is negative and the diagnosis of SLE remains unclear, the presence of high-titer anti-ssDNA still holds reference value for auxiliary diagnosis.

Furthermore, research indicates that many SLE patients have serum anti-DNA antibodies capable of reacting with both ssDNA and dsDNA, suggesting these antibodies recognize shared epitopes. This observation has led to ongoing discussions: some scholars propose that anti-ssDNA should not be entirely excluded from having pathogenic roles, as accumulating evidence hints at its potential involvement in inducing renal damage, though further studies are needed to confirm this mechanism.

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Principle

This kit is specifically designed for the qualitative and semi-quantitative detection of anti-single-stranded DNA (anti-ssDNA) antibodies in human serum or plasma samples. Its core working principle relies on the solid-phase enzyme-linked immunosorbent assay (ELISA) technique: polystyrene microwell strips are pre-coated with highly purified single-stranded DNA (ssDNA) antigen, which serves as the capture reagent for target antibodies in the specimens.

The detection process proceeds in several key steps. First, when serum or plasma specimens to be tested are added to the pre-coated wells, any specific anti-ssDNA antibodies present in the samples—primarily IgG subclass antibodies (ssDNA-IgG-Ab) and a small portion of IgM subclass antibodies (ssDNA-IgM-Ab)—will specifically bind to the immobilized ssDNA antigen on the solid phase through antigen-antibody interaction. After this incubation period, unbound components in the specimens, such as non-specific proteins and other antibodies, are thoroughly removed by washing to eliminate potential interference.

In the second step, horseradish peroxidase (HRP)-conjugated anti-human IgG secondary antibody is added to the wells. This enzyme-labeled antibody specifically recognizes and binds to the IgG-type anti-ssDNA antibodies that have already formed complexes with the ssDNA antigen, forming a stable "ssDNA antigen - anti-ssDNA IgG antibody - HRP-conjugated anti-human IgG" immune complex. A subsequent washing step is performed again to remove any unbound HRP conjugate, ensuring that only specifically bound enzyme-labeled antibodies remain in the wells.

Following the washing, a chromogenic solution containing TMB (3,3',5,5'-tetramethylbenzidine) substrate is added. In the presence of the immune complex, the HRP enzyme linked to the complex catalyzes the oxidation of TMB, generating a blue-colored product. The reaction is then terminated by adding 50μl of stop solution (typically a dilute sulfuric acid solution), which converts the blue substance to a stable yellow color.

Finally, the absorbance of each well is measured using a microplate reader at the appropriate wavelength (usually 450nm, with a reference wavelength of 630nm). The absorbance value is directly proportional to the concentration of anti-ssDNA IgG antibodies in the sample, allowing for the determination of both the presence and relative quantity of these antibodies in the tested specimens.

Product Features

High sensitivity, specificity and stability

Product Specification

Principle	Enzyme linked immunosorbent assay
Type	Indirect Method
Certificate	NMPA
Specimen	Human serum / plasma
Specification	48T / 96T
Storage temperature	2-8℃
Shelf life	12 months