Question

Which pathway of complement activation begins with the recognition of antigen-antibody complexes by the first component of complement, C1q, leading to subsequent steps involving activation of components C4, C2, C3, and the production of C3 convertase?

A) The classical pathway
B) The alternative pathway
C) The lectin pathway
D) The innate pathway

Answer 1

The classical pathway of complement activation begins with the recognition of antigen-antibody complexes by C1q, leading to subsequent steps involving activation of components C4, C2, C3, and the production of C3 convertase.

Step-by-step explanation:

The pathway of complement activation that begins with the recognition of antigen-antibody complexes by C1q and leads to subsequent steps involving activation of components C4, C2, C3, and the production of C3 convertase is called the classical pathway. In this pathway, C1 binds to an antigen-antibody complex on an invading pathogen, causing complement components C2 and C4 to split in two. This pathway is dependent on the adaptive immune response, as it requires the presence of antibody bound to the antigen.