Although the complement cascade can be initiated by antibodies bound to the surface of a pathogen, complement activation is generally considered to be an innate immune response. This is because:
A) Two of the three pathways for complement activation are initiated by constitutively produced recognition molecules that directly interact with microbial surfaces.
B) When the complement cascade leads to the formation of a membrane-attack complex, the pathogen is killed.
C) Several of the soluble products generated by complement activation lead promote the inflammatory response.
D) Complement proteins bound to the pathogen promote uptake and destruction by phagocytic cells.
E) The C3 convertase is only produced when complement activation is initiated by antibody binding to a pathogen.

Question

Quizplus · Accepted Answer

Two of the three pathways for complement activation (the lectin and alternative pathways) are initiated by constitutively produced recognition molecules that directly interact with microbial surfaces, indicating that complement activation is a part of the innate immune response. In contrast, the classical pathway is initiated by antibody binding to a pathogen, which is a part of the adaptive immune response.

Although the Complement Cascade Can Be Initiated by Antibodies Bound