Lecture 5 - Complement
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Questions and Answers

What role do C3a and C5a play in inflammation?

  • Suppress the opsonization of pathogens
  • Inhibit the release of proinflammatory cytokines
  • Recruit phagocytes and promote inflammation (correct)
  • Prevent anaphylactic shock

How do complement receptors connect complement-tagged pathogens to effector cells?

  • Through inhibition of proinflammatory cytokine release
  • By stimulating the release of granule components from phagocytes
  • By facilitating the binding of complement-tagged pathogens to effector cells (correct)
  • By promoting pathogen lysis

How does opsonization enhance phagocytosis?

  • Prevents pathogen lysis
  • Makes pathogens more readily taken up by phagocytosis (correct)
  • Reduces the uptake of pathogens by phagocytes
  • Promotes inflammation

What is the function of properdin (factor P) in the alternative pathway of complement activation?

<p>Stabilizes C3 convertase (C3bBb) (D)</p> Signup and view all the answers

Which complement factor creates the membrane-attack complex (MAC) that leads to pathogen lysis?

<p>Multiple complement factors (B)</p> Signup and view all the answers

What is the main downstream effect of large amounts of C3a and C5a?

<p>Anaphylactic shock (C)</p> Signup and view all the answers

What is the key mechanism of action of the complement system related to inflammation?

<p>Increasing vascular permeability and chemotaxis (D)</p> Signup and view all the answers

Which process involves the coating of a pathogen's surface to make it more easily ingested by phagocytes?

<p>Opsonization (A)</p> Signup and view all the answers

What is the main function of phagocytosis in cellular processes?

<p>Facilitating engulfment of pathogens (D)</p> Signup and view all the answers

How is the complement system initially activated?

<p>Via three pathways: Classical, Alternative, Lectin (D)</p> Signup and view all the answers

Which proteins circulate in the blood until activated and initiate their respective complement reactions?

<p>Pro-proteases (C)</p> Signup and view all the answers

Which fragment of the complement system identified by 'a' after its name has a specific function?

<p>'a' fragment (A)</p> Signup and view all the answers

What is the main function of C3 convertase in the complement system?

<p>Cleave C3 into C3a and C3b (D)</p> Signup and view all the answers

What is the role of negative regulation in complement activation?

<p>Preventing excessive activation and damage to host tissues (C)</p> Signup and view all the answers

Which pathway is triggered by soluble proteins known as lectins?

<p>Lectin pathway itself (D)</p> Signup and view all the answers

What is the role of pro-proteases in the complement system?

<p>Initiate complement reactions by cleaving and activating the next protein in the sequence (A)</p> Signup and view all the answers

What is one of the main outcomes of inhibiting the formation of MAC on host cells?

<p>Protection of host cells from damage (C)</p> Signup and view all the answers

Which protein prevents the appearance of C3 convertase under normal/basal conditions?

<p>CD59 (Protectin) (C)</p> Signup and view all the answers

Which molecule is involved in enhancing inflammation according to the text?

<p>C3a (D)</p> Signup and view all the answers

What is the main function of C3b as discussed in the text?

<p>Opsonization (D)</p> Signup and view all the answers

Which protein is involved in the negative regulation of MAC formation by inhibiting the assembly of the Membrane Attack Complex?

<p>CD59 (Protectin) (C)</p> Signup and view all the answers

Which pathway results in the generation of C3 convertase (C4b2a) according to the text?

<p>Classical pathway (C)</p> Signup and view all the answers

What is the function of C3b in the complement system?

<p>Pathogen lysis (B)</p> Signup and view all the answers

What initiates an amplification loop for C3b formation in the alternative pathway?

<p>Factor B and protease factor D (C)</p> Signup and view all the answers

Which outcome is NOT associated with complement activation?

<p>Pathogen growth promotion (A)</p> Signup and view all the answers

Which molecule is involved in phagocytosis enhancement in the complement system?

<p>C3b (B)</p> Signup and view all the answers

What happens under normal/basal conditions due to the presence of complement-regulatory proteins?

<p>Prevention of complement activation progression (B)</p> Signup and view all the answers

What is the role of C1q in the complement system based on the text?

<p>Directly binding pathogens (D)</p> Signup and view all the answers

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