Skip to main content
Back

Review of the Complement System definitions

Control buttons has been changed to "navigation" mode.
1/15
  • Complement System
    A group of inactive proteins in blood and tissues that, when activated, enhance immune responses against microbes.
  • Alternative Pathway
    A route of complement activation initiated by C3b binding directly to microbial surfaces, independent of antibodies.
  • Lectin Pathway
    A complement activation route triggered by mannose binding lectin attaching to mannose residues on microbes.
  • Classical Pathway
    A complement activation route initiated when antibodies bind to antigens on microbes, linking innate and adaptive immunity.
  • C3 Convertase
    An enzyme complex formed in all complement pathways that cleaves C3 into C3a and C3b, amplifying immune responses.
  • C3b
    A complement fragment that binds to microbes, acts as an opsonin, and helps form membrane attack complexes.
  • C3a
    A small peptide generated from C3 cleavage that promotes inflammation and recruits immune cells.
  • Mannose Binding Lectin
    A protein that recognizes and binds to mannose sugars on microbial surfaces, initiating the lectin pathway.
  • Antibody
    A molecule from adaptive immunity that binds antigens on microbes, triggering the classical complement pathway.
  • Antigen
    A molecular structure on microbes recognized by antibodies, leading to immune activation.
  • Opsonization
    A process where molecules like C3b coat microbes, enhancing their uptake and destruction by phagocytes.
  • Phagocytosis
    A cellular process where immune cells engulf and digest microbes, aided by opsonins like C3b.
  • Membrane Attack Complex
    A structure formed by complement proteins that creates pores in microbial membranes, causing cell lysis.
  • Inflammation
    A protective response involving immune cell recruitment and increased blood flow, often triggered by C3a and C5a.
  • Innate Immunity
    A non-specific defense system including the complement system, providing immediate protection against pathogens.