Properdin ELISA Kit [Human], 1 x 96 det. (CAT#: CB-P107-K) Datasheet

Kit

Properdin or factor P is a single-chain plasma glycoprotein (apparent molecular weight 52-55 kDa) composed of six thrombospondin repeats between short N- and C-terminal domains​​. In the blood, it exists as a mixture of head-to-tail dimers, trimers and tetramers, and mainly trimers.
The protein is produced by a variety of white blood cells, including monocytes, T lymphocytes, and neutrophils, but is also produced by endothelial cells, where the shear force induces the synthesis and release of properdin.
Properdin, together with C3 and factors B, D, I and H, participate in alternative pathways of complement activation. It can stabilize the unstable C3bBb deposited on immune complexes or foreign surfaces. This allows the formation of C3bBb to be amplified in the competition between factor I and C3b catabolism using factor H as a cofactor. The local amplification process leads to the production of the alternative pathway C5 convertase C3bBb3b and initiates the terminal pathway of complement activation.
Properdin extends the half-life of surface-bound C3bBb from 1.5 minutes to about 18 minutes. This is due to several effects: Factor I inhibits the cleavage of C3b, increases the affinity for factor B, and inhibits the breakdown of C3bBb into C3b and Bb. Properdin is consumed by binding to C3bBb. This binding shows the order of tetramers in preference to trimers rather than dimers, which is also the order of functional activity of the oligomeric form.
Depending on the exact nature of the defect, the lack of molecules or functional abnormalities may cause serious damage to the activation of alternative pathways. One parameter of functional defect in the presence of measurable levels of protein is the impaired production of more active tetrameric and trimer forms.
The properdin gene is located on the short arm of the X chromosome, so congenital properdin defects are inherited as a typical X-linked recessive feature.
Three types of family defects have been described: Type 1 (or type I) is characterized by very low or non-existent properdin activity in serum and <0.1 μg/ml immunoreactive protein in hemolysis assays. Type 2 (or type II) is characterized by low but detectable levels of immunoreactive protein (»2μg/ml), some (but not all) functional tests are impaired, and type 3 (or III) has a normal level of immune response But dysfunction protein. 10 The content of properdin in normal serum or plasma is approximately 5 or 25 µg/ml. The difference of properdin levels in healthy people and diabetic people (Chaudhry_B_2008)

Human Properdin ELISA kit is used for the in vitro quantitative determination of human Properdin in serum, plasma, bronchoalveolar lavage fluid, urine and cerebrospinal fluid samples.

Human Properdin ELISA kit is a ready-to-use solid-phase enzyme-linked immunosorbent assay based on the sandwich principle. The working time is 3 hours. The effective form of the plate with twelve disposable 8-well plates allows free choice of batch size for determination. The samples and standards are incubated in microtiter wells coated with antibodies that recognize human Properdin. The biotinylated tracer antibody will bind to the captured human Properdin. The streptavidin-peroxidase conjugate will bind the biotinylated tracer antibody. The streptavidin-peroxidase conjugate will react with the substrate tetramethylbenzidine (TMB). The enzyme reaction is stopped by adding oxalic acid. Measure the absorbance at 450nm with a spectrophotometer. The standard curve is obtained by plotting the absorbance (linear) versus the corresponding concentration (logarithm) of the human Properdin standard. The concentration of human Properdin in the sample run at the same time as the standard can be determined from the standard curve.