Final answer:
C-reactive protein and mannose-binding lectin are acute-phase proteins (option a) that activate the lectin pathway of the complement system upon binding to a pathogen, leading to the opsonization and elimination of the pathogen.
Step-by-step explanation:
C-reactive protein and mannose-binding lectin are classified as acute-phase proteins. These proteins play a crucial role in the innate immune response, becoming elevated in response to inflammation. When acute-phase proteins like mannose-binding lectin bind to a pathogen, they activate the complement system, specifically the lectin pathway. This leads to a cascade of events that facilitate the destruction of pathogens through opsonization and other immune processes.
The complement system is a complex set of proteins, about 20 in total, that work in a cascading fashion to mark and destroy pathogens. This system forms a bridge between the innate and adaptive immune systems. Proteins like mannose-binding lectin and C-reactive protein are synthesized in the liver and assist in the recognition and elimination of pathogens by enhancing the process known as opsonization. The lectin pathway of complement activation is specifically triggered by binding of mannose-binding lectin to a pathogen.