What are the 3 pathways of complement activation?

There are three pathways of complement activation: the classical pathway, which is triggered directly by pathogen or indirectly by antibody binding to the pathogen surface; the MB-lectin pathway; and the alternative pathway, which also provides an amplification loop for the other two pathways.

What is the C3 convertase of the classical and MB lectin pathways?

Lectin pathway activation of C3 is known to involve target recognition by mannan-binding lectin (MBL) or ficolins and generation of classical pathway C3 convertase via cleavage of C4 and C2 by MBL-associated serine protease 2 (MASP-2).

How is MBL pathway activated?

Activation of the lectin pathway occurs through the binding of the complex of mannose-binding lectin (MBL), CL-K1 or ficolins, and MBL-associated serine proteases 1 and 2 (MASP-1 and MASP-2, respectively) to various carbohydrates or acetylated residues on the surface of pathogens (PAMP, pathogen-associated molecular …

Is lectin pathway innate or adaptive?

The classical complement pathway is activated by antibody–antigen complexes on the bacterial surface and has been considered predominately to be an effector of the adaptive immune response, whereas the alternative and mannose-binding lectin pathways are activated directly by bacterial cell surface components and are …

What is the difference between classical pathway and lectin pathway?

The main difference between classical and alternative pathway is that the initiation of alternative pathways is not dependent on the presence of immune complexes. The lectin pathway is activated following the recognition and binding of pathogen-associated molecular patterns (PAMPs) by mannose-binding lectin (MBL) [27].

What is the role of C3a C4a and C5a in the immune response?

Role of anaphylatoxins C3a and C5a. Anaphylatoxins C3a and C5a participate in inflammation by interacting and activating immune cells via C3aR and C5aR, respectively. C3a is implicated in the adaptive immunity by inducing monoclonal response from B cells and up-regulation of pro- inflammatory cytokines.

What is the alternative pathway C3 convertase?

C3 Convertase of Alternative Pathway C3 enzyme is responsible for amplification of pathway activation and for deposition on target cells of C3b and the membrane attack complex. It is controlled by the serum proteins Factor H, Factor I (EC 3.4. 21.45), and properdin.

How is classical complement pathway differ from lectin pathway?

The classical complement pathway is activated by antibody-antigen complexes on the bacterial surface and has been considered predominately to be an effector of the adaptive immune response, whereas the alternative and mannose-binding lectin pathways are activated directly by bacterial cell surface components and are …

How does the lectin pathway differ from the classical pathway?

What is the difference between the classical and alternative pathway of the complement system?

The classical complement pathway typically requires antigen—antibody complexes (immune complexes) for activation (specific immune response), whereas the alternative pathway can be activated by C3 hydrolysis, foreign material, pathogens, or damaged cells.