Human sC5b-9(Soluble Terminal Complement Complex C5b-9) ELISA Kit (E-EL-H2376)

This ELISA kit uses the Sandwich-ELISA principle. The micro ELISA plate provided in this kit has been pre-coated with an antibody specific to Human sC5b-9. Standards or samples are added to the micro ELISA plate wells and combined with the specific antibody. Then a biotinylated detection antibody specific for Human sC5b-9 and Avidin-Horseradish Peroxidase (HRP) conjugate are added successively to each micro plate well and incubated. Free components are washed away. The substrate solution is added to each well. Only those wells that contain Human sC5b-9, biotinylated detection antibody and Avidin-HRP conjugate will appear blue in color. The enzyme-substrate reaction is terminated by the addition of stop solution and the color turns yellow. The optical density (OD) is measured spectrophotometrically at a wavelength of 450 nm ± 2 nm. The OD value is proportional to the concentration of Human sC5b-9. You can calculate the concentration of Human sC5b-9 in the samples by comparing the OD of the samples to the standard curve.

The soluble terminal complement complex sC5b-9, also termed the soluble membrane attack complex, is the terminal product of complement activation. It is assembled when C5 convertase cleaves C5 to C5b, which then binds C6, C7 and C8 and polymerizes multiple C9 molecules into a pore-forming C5b-9 complex. Assembled on pathogen or host cell surfaces, the membrane attack complex disrupts membrane integrity and causes osmotic lysis, whereas complexes formed in the fluid phase bind vitronectin (S protein) and clusterin and remain soluble in the circulation. sC5b-9 is the standard marker of terminal complement pathway activation and reflects the integrated activity of the classical, lectin and alternative cascades, since all three converge on C5. Sublytic deposition of C5b-9 on nucleated cells additionally triggers intracellular signaling, calcium flux, release of inflammatory mediators, tissue-factor expression, endothelial activation and platelet activation, so the complex functions both as an effector of lysis and as an amplifier of inflammation, coagulation and microvascular injury. Measurement of sC5b-9 is used to assess complement activation and is valuable in the diagnosis, activity assessment and monitoring of atypical hemolytic uremic syndrome, paroxysmal nocturnal hemoglobinuria, C3 glomerulopathy, systemic lupus erythematosus, antiphospholipid syndrome, antibody-mediated transplant rejection, catastrophic antiphospholipid syndrome and severe infection. It also serves as a pharmacodynamic biomarker for evaluating the efficacy and dosing of complement-targeted therapy such as C5 inhibitors.