Molecular Classification
Anaphylatoxin, Chemotactic factor, Complement component
Disease Roles
SepsisAcute lung injuryIschemia-reperfusion injury

Complement component C5a Overview

Complement component C5a is a potent, 74-amino acid glycoprotein fragment (~11 kDa) generated by the enzymatic cleavage of complement component C5 by C5 convertase. It acts as a highly inflammatory peptide with multiple roles in immune regulation and inflammation, functioning as both an anaphylatoxin and a chemotactic agent.

Mechanism of Action

C5a exerts its effects primarily through binding two G protein-coupled receptors: C5aR1 (CD88) and C5L2 (GPR77), triggering intracellular signaling cascades involving G proteins, β-arrestin recruitment, ERK1/2 phosphorylation, and calcium mobilization.

Biological Functions

Anaphylaxis
Chemotaxis
Inflammation
Immune modulation
Cytokine production
Leukocyte activation

Disease Associations

Sepsis
Acute lung injury
Ischemia-reperfusion injury
Asthma
Inflammatory diseases
Tumor progression

Safety Considerations

  • Excessive or dysregulated production/activity of C5a has been implicated in numerous acute/chronic inflammatory diseases.
  • High levels within tumor microenvironments may suppress anti-tumor T-cell responses.