Properdin is an innate modifier of complement. It performs several functions which contribute to up regulation of the complement response, inhibiting down regulators’ ability to bind and cleave functional components of the cascade, as well as stabilizing the C3 and C5 convertases of the AP, decreasing their disassociation rates.
Properdin is mainly synthesized by leucocytes, in contrast to the majority of complement proteins, which are synthesized in the liver. In response to inflammatory triggers, it is quickly released and stabilizes the assembly of C3 and C5 convertases.
Read more about Properdin and Factor P assays here:
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