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Catalog # HK355

Complement factor I, Human, ELISA kit

Complement Factor I (CFI), a vital serine protease encoded by the chromosome 4 CFI gene, regulates the immune system by selectively inactivating C3b and C4b in the complement cascade.

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The serine protease Complement Factor I (CFI), encoded by the CFI gene, acts as a pivotal C3b/C4b inactivator, regulating the complement system by targeting and cleaving these molecules effectively. Produced mainly in the liver, CFI transforms from a precursor protein into a potent dimer, essential for immune function. Variations in the CFI gene affect its activity, with deficiencies potentially reducing C3 levels, leading to increased infection risks and conditions like Haemolytic Uremic Syndrome due to unregulated complement activity.

The complement factor I ELISA kit is to be used for the in vitro quantitative determination of human CFI in plasma and serum.

The complement factor I ELISA is a ready-to-use solid-phase enzyme-linked immunosorbent assay based on the sandwich principle with a working time of 3½ hours. The efficient format of a plate with twelve disposable 8-well strips allows free choice of batch size for the assay. Samples and standards are incubated in microtiter wells coated with antibodies recognizing human CFI. Biotinylated tracer antibody will bind to the captured human CFI. Streptavidin-peroxidase conjugate will bind to the biotinylated tracer antibody. Streptavidin-peroxidase conjugate will react with the substrate, tetramethylbenzidine (TMB). The enzyme reaction is stopped by the addition of oxalic acid. The absorbance at 450 nm is measured with a spectrophotometer. A standard curve is obtained by plotting the absorbance (linear) versus the corresponding concentrations of the human CFI standards (log). The human CFI concentration of samples, which are run concurrently with the standards, can be determined from the standard curve.

Recovery was determined by mixing CFI depleted serum with different plasma samples with a known CFI concentration. Samples were incubated for one hour at room temperature and measured using the ELISA. The recovery experiment met the requirements and ranged between 87.1% and 109.2%

Precision and reproducibility
The intra-assay precision and reproducibility was tested using four samples with three different dilutions. CV % ranged between 0.5 and 7.1%. To determine the inter-assay variation, four samples were tested by two operators both on three separate days. CV % ranged between 6.7 and 9.6%.

Product type
1 x 96 det., 2 x 96 det.
Standard range
Measurable concentration range of 35.1 to 400 ng/ml.
Detection level
Minimum concentration which can be measured is 35.1 ng/ml.
Working volume
100 µl/well
Cross reactivity
Mouse – No, Pig – No, Rat – No
CFI, C3b-Inactivator, C3b/C4b inactivator, Konglutinogen-Activating Factor
Storage and stability
Product should be stored at 4 °C. Under recommended storage conditions, product is stable for at least six months.
For research use only. Not for use in or on humans or animals or for diagnostics. It is the responsibility of the user to comply with all local/state and Federal rules in the use of this product. Hycult Biotech is not responsible for any patent infringements that might result with the use of or derivation of this product.
Autoimmunity, Nephrology
Safety Data Sheet Assay Manual
394 kb

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