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Catalog # HK3012

Alternative Complement Pathway, Human, Assay

The Human Alternative Complement Pathway ELISA kit is to be used for the in vitro quantitative determination of Alternative Complement Pathway activity in serum samples.

The ELISA can also be used to determine the effect of inhibitory compounds for the alternative pathway.


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Features activity assay:

  • Quantitative measurement of complement activation
  • Working at low serum dilutions resulting in less false negative results
  • High throughput and offers higher reproducibility in comparison to hemolytic assays
  • Assay time less than 2 hours

The complement system plays essential roles in both innate and adaptive immune responses, providing inflammatory and protective reactions against pathogens. Comprising a complex family of proteins and receptors found in circulation, tissues, and body fluids, it operates through three activation pathways: the classical pathway (CP), initiated by immune complexes; the lectin pathway (LP), activated by surface-bound lectins; and the alternative complement pathway (AP), triggered on surfaces lacking specific protection.

The AP activation involves spontaneous C3 hydrolysis, binding to fB, forming C3(H2O)Bb convertase, which can be stabilized by properdin. Regulation comes from proteins like fH and fI. All pathways produce a C3 convertase, cleaving C3 into the major fragment C3b. These pathways converge with C3b initiating the second convertase, the C5 convertase, cleaving C5 into C5a and C5b, amplifying complement activity and forming the cytolytic MAC.

Complement protein assessment, or complement activity, helps identify system abnormalities in vivo and screen for complement inhibitor function. Traditionally, haemolysis assays were used, but they’re challenging to standardize due to complications like opsonization and erythrocyte stability. ELISA-based assays, while more versatile, face challenges from serum dilutions. The HK3012 AP complement activity assay addresses these issues, offering a standardized approach. With the high costs of complement inhibitors and the need for more potent options, accurate measurement of complement activity is crucial.

The HK3012 Alternative complement pathway activity assay evaluates complement function in vitro using LPS-coated wells to detect the in vitro-formed MAC complex with a C9 neo-epitope antibody. It begins with a serum dilution of 7.5x and uses a specific buffer to prevent pathway interference. Employing a 1.5-fold dilution combined with regression analysis, it accurately measures complement activity and inhibitory capacity.

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Functional studies, Immuno assays

The Human Alternative Complement Pathway ELISA kit is to be used for the in vitro quantitative determination of Alternative Complement Pathway activity in serum samples. The ELISA can also be used to determine the effect of inhibitory compounds for the alternative pathway.

The Human Alternative Complement Pathway ELISA is a ready-to-use solid-phase enzyme-linked immunosorbent activity assay based on the sandwich principle with a working time of 1 hour and 45 minutes. The efficient format of a plate with twelve disposable 8-well strips allows free choice of batch size for the assay. Samples and positive control are incubated in microtiter wells coated with LPS. Peroxidase-conjugated antibody will bind a neo-epitope of to the formed TCC complex. 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. The Human Alternative Complement Pathway activity of samples, which are run concurrently with the standards, can be evaluated on OD-data using regression analysis on logistically transformed values. Complement activity can be expressed as percentage of the activity of a positive standard serum.

1 x 96 det.
Product type
Working volume
100 µl/well
Cross reactivity
Monkey – Yes, Pig – Yes
Complement Activity Assay
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.
Safety Data Sheet Assay Manual
1483 kb
Technical Data

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