Classical complement cascade

Definition

The classical complement cascade is a sequence of protein interactions in the immune system activated by antibodies bound to antigens. It enhances inflammation, opsonization, and cell lysis.

5 Must Know Facts For Your Next Test

1. Activation begins when antibodies IgG or IgM bind to antigens.
2. C1 complex (comprising C1q, C1r, and C1s) initiates the cascade.
3. The cascade results in the formation of the Membrane Attack Complex (MAC), leading to cell lysis.
4. C3 convertase plays a crucial role by cleaving C3 into C3a and C3b.
5. Deficiencies in components of this pathway can lead to increased susceptibility to infections.

Related terms

Antigen:

A substance that induces an immune response, often by binding to specific antibodies.

Opsonization:

The process where pathogens are marked for ingestion and elimination by phagocytes.

Membrane Attack Complex (MAC): A structure formed on pathogen surfaces leading to cell lysis as a result of complement activation.