Complement And Cytokines Flashcards
What are three phagocytes?
Neutrophils, monocytes/macrophages
• kill virally infected and tumor cells
• Produce cytokines
Natural killer cells
This enhances phagocytosis, recruit cells, kills cells/bacteria
Complement
Accumulation of fluids and white blood cells to localized and remove irritant
Inflammation
-set of plasma proteins that work together to facilitate the destruction and removal of pathogens
-Also play a role in regulation of immunity and tissue damage due to auto immune or hypersensitivity reactions
Complement system
What are the major functions of complement?
-localized vasodilation and attract phagocytic cells (anaphylatoxins)
-Enhance phagocytosis (Opsonization)
-Lysis of cells, bacteria, viruses [Membrane attack complex MAC] (Form spores in the membrane)
-clearance of soluble immune complexes
-Small soluble fragments of complement proteins (C5a, C3a)
-participates in Inflammation (Vasodilation, vascular permeability, activate mass cells, recruits phagocytosis to side of antigen deposition) 
Anaphylatoxins
-enhances phagocytosis of complement coated pathogens due to receptors on macrophages or PMN
-C3b and C4b- opsonins
Opsonization
- Remember antibody IgG is also an opsonin 
Explain lysis…
-Membrane attack complex MAC formation results in pore
through membrane
-attack cells, extracellular pathogens and virons (Extracellular viruses)
-C5b, C6, C7, C8, C9 Heart sequentially assembled into MAC
Soluble immune complexes (Antigen – antibody) In circulation needs to be cleared. If not, what happens? 
Immune complexes deposit in tissues such as kidneys
How are immune complexes cleared out of the body? 
-RBC bind to C3 on immune complexes
-RBC carry complexes to spleen and liver for disposal by macrophages
What are the three complement pathways?
• classical pathway
• Alternative pathway
• Lectin pathway
Pathway that is anybody directed
Classical pathway
This pathway is initiated by C1q Binding to immune complexes 
Classical pathway
This pathway is associated with innate immunity and can enhance classical pathway
Alternative pathway
This pathway is initiated by C3b binding to surface of bacteria
Alternative pathway
This pathway is associated with innate immunity
Lectin pathway
Mannose-binding Lectin (MBL) Binding to Mannose residues On bacterial cell surface
Lectin pathway
What is the order of classical pathway activation?
C1q, C1r, C1s, C4, C2, C3, C5, C6, C7, C8, C9
Alternative pathway: Factor ___, Factor ____, and __________.
B, D, properdin
What do proteases do?
Cleave proteins
Many components become pro teases after cleavage into two fragments. what is an exception?
C2a which is the larger and bound, while C2b is smaller and soluble
Many components become pro teases after cleavage into two fragments. What is an example? 
-small Soluble fragment “a”
-Larger bound fragment “b” 
Complement system:
C3 Convertase cleaves C3 into ___ and ____
C3a and C3b
-classical: C4b2a (Enzymatic activity)
-Alternative: C3bBb (enzymatic activity)
Complement system:
Addition of C3b to C3 convertase results in….
C5 convertase (C5–> C5a + C5b)
Classical: C4b2a3b (Enzymatic activity)
Alternative: C3bBb3b (enzymatic activity) 
Alternative can amplify ___________ Pathway
Classical
