C3bBbP, Human, ELISA kit

The complement system is a vital component of innate immunity, serving initially as the first line of defense against pathogens. It consists of three activation pathways: the classical, lectin, and alternative pathways, all converging at the activation of complement protein C3. The alternative pathway is unique in its ability to amplify immune responses via the formation of the C3 convertase complex, C3bBb, which plays a crucial role in pathogen clearance and immune surveillance.

C3bBbP, also known as the properdin-stabilized C3 convertase, is an extended form of C3bBb. Properdin, the only known positive regulator of complement activity, binds to C3bBb, increasing its stability and prolonging its function. This stabilization enhances the cleavage of C3 into C3a and C3b, leading to a powerful amplification loop that ensures rapid immune responses. However, dysregulation of this mechanism can contribute to pathological conditions.

Elevated levels of C3bBbP have been implicated in complement-mediated diseases, including C3 glomerulopathy (C3G) and atypical hemolytic uremic syndrome (aHUS). These disorders are characterized by excessive complement activation, leading to uncontrolled inflammation and tissue damage. Additionally, the presence of nephritic factors (autoantibodies that stabilize C3bBbP) can further disrupt complement homeostasis, exacerbating disease progression.

The detection of C3bBbP serves as a potential diagnostic biomarker for alternative pathway complement-associated diseases. Its measurement helps to assess alternative pathway activity, providing valuable insights into disease mechanisms and possibly guiding complement-targeted therapies. As complement-directed treatments continue to progress, the role of C3bBbP is becoming increasingly significant.