Exam 1: Dr. Pruett Chapter 4 Flashcards
What is often a problem with Brittany dogs?
Cannot make complement component 3 (C3)
What is often a problem that results from not being able to make C3?
It leads to kidney failure and a shorter life span
Which pathway(s) require antibody? Which do not?
Classical requires antibody
Lectin and alternative do not
What is the general process of the complement pathways?
Starts with an inactive enzyme that becomes activated and cleaves the next enzyme. It is a continuous chain
Explain the process of the pathways, specifically, starting with C3 convertase.
C3 convertase cleaves C3 into C3a and C3b. C3b activates C5 convertase, which cleaves C5 into C5a and C5b
What is C5b6789 also known as?
The membrane attack complex
Since the lectin and alternative pathwways do not use antibody, what do they do?
They use microbes that always exist in the body. They require no contribution from the adaptive/acquired system
What does the C1 complex consist of?
C1q, r, and s
What is C1q?
The binding component
What are C1r and C1s?
Enzymes
What does the bindnig of C1q to Ab/Ag complex do?
Activates C1r, which activates C1s, which activates C2 and C4
Know and understand the classical pathway (page 57)
Know and understand the classical pathway (page 57)
Know and understand the lectin pathway (page 58)
Know and understand the lectin pathway (page 58)
Know and understand the alternative pathway (page 59)
Know and understand the alternative pathway (page 59)
What does C3 undergo in the alternative pathway?
Spontaneous hydrolysis reaction
Describe how the membrane attack complex is formed?
C5b recruits C6 and C7 to the target membrane, forming the complex C5b67
C8 binds to the C5b67 complex, unfolding a hydrophobic region that wedges into the target membrane
Recruit and insert 10-16 copies of C9 into the membrane to create a cylindrical pore
Describe what the membrane attack complex does?
MAC breaches the cell membrane of the microbes allowing water to rush in to the cell
Osmotic lysis of the microbe by sufficient number of MAC in the membrane
What are different outcomes of complement activation?
Direct target lysis Tissue inflammation Endothelial activation Chemotaxis Leukocyte activation Opsonization
What is the action of direct target lysis?
Osmodysregulation and lysis of target cells
What is the action of tissue inflammation?
Activation of mast cell degranulation leading to release of vasoactive amines
What is the action of endothelial activation?
Increased expression of adhesion molecules
What is the action of chemotaxis?
Promotes migration of neutrophils, eosinophils, and macrophages toward the site of complement activation
What is the action of leukocyte activation?
Upregulation of adhesion molecules, phagocytic receptors, and antimicrobial effectors by neutrophils and monocytes
What is the action of opsonization?
Enhancement of particle phagocytosis by macrophages and neutrophils
What are some of the complement control proteins?
C1 inhibitor Factor H Decay-accelerating factor (CD55) Complement receptor I Protectin
What does C1 inhibitor do?
Inactivates C1r, C1s, and MASPs
What does factor H do?
Binds C3b and accelerates decay
What does decay-accelerating factor (CD55) do?
Accelerates decay of C3 convertase
What does complement receptor I do?
Binds C3b and C4a and inhibits alternative and classical/lectin C3 convertases
What does protectin do?
Binds to C5b678 and prevents C9 recruitment and MAC formation
What does Louis Pillemer and his team discover?
Properdin
What are 2 important points about Pillemer’s resarch?
Attention to detail is critical
Persistence is essential
What is C5b678 known as?
Scaffold portion of MAC
Which portion of the MAC makes the pore?
C9
Which portion of the MAC is hydrophobic and wedges in the membrane?
C8
