Chapter 12 Cytokines Flashcards
Which cells produce cytokines? Function?
All cells of innate and acquired immune system. They function as chemical messengers of the immune system. You can compare them to hormones of the endocrine system
General properties of cytokines?
-Polypeptides
-Communicate between cells at low concentrations of 10^-10 to 10^-5
-Bind specific receptors to exert effect
-Short half life of HOURS
-Pleiotropic: affect variety of cell types
-Redundant: have similar functions in different cells
-Rarely act alone, but are additive, synergistic, and antagonistic
What does it mean for cytokines to be additive, synergistic, or antagonistic?
Additive = effects directly sum
Synergistic = amplify signal together (2+2=6)
Antagonistic = one cytokine inhibits another
What does autocrine mean?
Cell secretes cytokine that exerts effect on self
What does paracrine mean?
Cell secretes cytokines that act on near-by cells
What does endocrine mean?
Cell secretes cytokines (hormones) that have systemic effect, travel to a completely different location
Cytokines impact cell ______.
Proliferation
Which cells express functional cytokine receptors?
Only cells stimulated by antigen, meaning that cytokines act only on Ag-activated lymphocytes
How does the body ensure immune specificity?
- Cytokines only act on Ag-stimulated cells
- Cell-cell contact required for stimulated cells (APC and Th)
- Limited action due to short half-life
Example of pleiotropy involving IL-4?
Activated Th cell secretes IL-4, which causes the proliferation of B, T, and mast cells. B cells are also activated and differentiated
What are Th0 cells?
They are naive T cells that differentiate into Th1 or Th2 cells
What influences differentiation of Th0 cells?
Cytokines released by APC, NK, and mast cells
What does Th1 pathway do?
Facilitates cell-mediated immunity. Th1 cells present antigen to Tc cells
What does the Th2 pathway do?
Essential for humoral immunity. Help B cells class switch to IgE during allergic responses, defend against parasitic worms, mobilize eosinophils
Describe the long- vs short-term aspects of Th1 and Th2 pathways
Th1 = long-term
Th2 = short term
Function of Th17?
Link adaptive and innate immunity through releasing IL-17. May play role in autoimmune disease
Which cytokine blocks monocyte activation?
TGF-beta
What is a pyrogen?
Fever-inducer
Bacteria and viruses stimulate which cells to release which cytokines to stimulate Th1 pathway?
NK cells and macrophages release IL-2, IFN-gamma, and TNF-beta to make Th0 mature into Th1
Parasitic worms cause which cells to stimulate which cytokines to induce Th2 pathway?
Mast cells and NK cells make IL-4 to induce Th0 to Th2
List cytokines produced by Th1 cells
IL-2, IFN-gamma, and TNF-beta
Which cytokines do Th2 cells produce?
IL-4, IL-5, and IL-10
Th2 cells release which cytokine to inhibit activation of Th1?
IL-10
Th1 cells release which cytokine to inhibitor activation of Th2?
IFN-gamma
Which endogenous pyrogens (cytokines) do macrophages and neutrophils release during innate immune response?
IL-1, IL-6, and TNF-alpha
What do the pyrogenic cytokines (IL-1, IL6, and TNF-alpha) induce?
Acute phase proteins such as C-reactive protein (produced in liver)
What does CRP bind? What does it do?
Binds phosphorylcholine. Acts as opsonin to activate complement
What is the purpose of mannose-binding lectin (MBL)?
Opsonin for activating complement. Binds mannose on bacteria. Mimics Ab action by binding bacteria and activating complement.