Immune Responses Flashcards
What is Complement?
System of interacting proteins that play a role in innate immunity & inflammation
What do Membrane attack complex (MAC) of complement do?
Defends against gram-negative bacteria
What is the Classic pathway of activation of complement?
IgG or IgM mediated
What is the Alternative pathway of activation of complement?
Microbe surface molecules
What is the Lectin pathway of activation of complement?
Mannose or other sugars on microbe surface
What is the function of C3b?
Opsonization
What is the function of C3a & C5a?
Anaphylaxis
What is the function of C5a?
Neutrophil chemotaxis
What is the function of C5b-9?
cytolysis by MAC
What are the two 1° opsonins in bacterial defense?
C3b & IgG
What does C3b help clear?
Immune complexes
What are the inhibitors of complement?
Decay-accelerating factor (DAF) & C1 esterase inhibitor help prevent complement activation on self cells
What is C1 esterase inhibitor deficiency?
Hereditary angioedema
What is CI w/ C1 esterase inhibitor deficiency?
ACE inhibitors
What is C3 deficiency?
Severe, recurrent pyogenic sinus & resp tract infections
What does C3 deficiency inc susceptibilty to?
Type III hypersensitivity reactions
What is C5-C9 deficiency?
Recurrent Neisseria bactermia
What is DAF (GPI anchored enzyme) deficiency?
Complement-med lysis of RBC’s & paroxysmal nocturnal hemoglobinuria (PNH)
Which cytokines are secreted by macrophages?
- IL-1
- IL-6
- IL-8
- IL-12
- TNF-alpha
What is IL-1?
An endogenous pyrogen
What does IL-1 cause?
Fever & acute inflammation
What does IL-1 activate?
Endothelium to express adhesion molecules; induces chemokine secretion to recruit leukocytes
What is IL-6?
Endogenous pyrogen
What is IL-6 secreted by?
Macrophages & Th2 cells
What does IL-6 cause?
Fever & stim production of acute-phase proteins
What is IL-8?
Major chemotactic factor for neutrophils
What is IL-12?
Induces indifferentation of T cells into Th1 cells & activates NK cells
What is IL-12 secreted by?
Macrophages & B cells
What does TNF-alpha do?
- Mediats septic shock
- Activates endothelium
- Causes leukocyte recruitment & vascular leak
Which cytokines are secreted by all T cells?
IL-2 & IL-3
What does IL-2 do?
Stim growth of helper, cytotoxic & regulatory T cells
What does IL-3 do?
Supports the growth & differntiation of bone marrow stem cells. Functions like GM-CSF
Which cytokines are secreted by Th1 cells?
Interferon-gamma
What does Interferon-gamma do?
- Activates macrophages & Th1 cells
- Suppresses Th2 cells
- Has antiviral & antitumor properties