Answer :
Activation of complement occurs following entry of a pathogen into the body. Two of the major means of activation include the Classical pathway and alternative pathway
Activation of complement occurs following entry of a pathogen into the body. The two major means of activation are the classical pathway and the alternative pathway.
The classical pathway is initiated by antigen-antibody complexes, where C1q binds to the Fc portion of IgM or IgG antibodies.
In contrast, the alternative pathway is triggered directly by the presence of microbial cell wall components such as lipopolysaccharides (LPS), lipoteichoic acid (LTA), and β-glucans.
Both pathways converge at the formation of C3 convertase, which cleaves C3 into C3a and C3b, leading to further activation of the complement cascade.
This activation results in opsonization, chemotaxis, and lysis of pathogens, enhancing the immune response against them.
The classical and alternative pathways thus represent distinct but interconnected mechanisms for initiating the complement cascade in response to pathogenic invasion.
Explaining the activation of complement, we find that the classical pathway starts with antigen-antibody complexes, while the alternative pathway is triggered directly by microbial components. Both pathways converge at C3 convertase, leading to complement cascade activation, aiding in pathogen elimination.
