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Catalog # HK343

Complement factor D, Human, ELISA kit


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The alternative pathway of complement represents an important humoral component of natural defense against microbial attack. The interaction of the proteins C3, factor B, and factor D results in the formation of the alternative C3- and C5-convertases, i.e. C3bBb and C3bBbC3b(n). These multicomponent enzymes assemble on the surface of alternative pathway of complement activators and are stabilized by properdin (P). The participation of the alternative pathway of complement has been implicated in the pathogenesis of a wide variety of human diseases.
Factor D, a 24 kD serine protease of the alternative complement pathway, is synthesized as a precursor single-chain molecule. Factor D is unique among serine proteases because it requires neither enzymatic cleavage for expression of proteolytic activity nor activation by a serpin for its control. Factor D is highly specific and cleaves factor B bound to C3b, generating the C3bBb enzyme. Factor D is the rate-linking C3 convertase enzyme of the alternative pathway. Furthermore, factor D plays a role in fatty tissue distinct from its role as a complement protein.
Normal values in human EDTA plasma are 1.05 (± 0.27) μg/ml. In healthy individuals factor D is rapidly eliminated via the kidney and neither modified extrarenal catabolism nor changes in synthesis contribute to elevated factor D levels observed in patients with renal failure. The levels in patients with chronic renal failure (CRF) increase up to 4.35 (± 3.03) μg/ml and in end-stage renal disease (ERDS) up to 12.1 (± 3.53) μg/ml.
Measurable quantities of factor D were detected in urine of 85% of healthy individuals (0.62 ± 0.33 ng/ml). The urinary concentrations of factor D in patients with tubular proteinuria are elevated to 230 (± 313) ng/ml.

The human complement factor D ELISA kit is to be used for the in vitro quantitative determination of human complement factor D in serum, plasma and urine samples.

The human complement factor D 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 2 plates 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 complement factor D. Biotinylated tracer antibody will bind to the captured human complement factor D. 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 complement factor D standards (log). The human complement factor D concentration of samples, which are run concurrently with the standards, can be determined from the standard curve.

Product type
1 x 96 det., 2 x 96 det.
Standard range
1.8 to 20 ng/ml
Detection level
1.8 ng/ml
Working volume
100 µl/well
Cross reactivity
Horse – Weak, Mouse – No, Rabbit – No, Swine – Weak
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 from the use or derivation of this product.
Infectious diseases, Nephrology
Safety Data Sheet Assay Manual
396 kb

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