Step 1 Immunology Flashcards
IL-2
- INDUCES T-CELL PROLIFERATION: Autocrine action. Secreted by activated T-cell. Binds to CD25 receptor on T-cell that secreted it to to cause proliferation. Amplifies the immune response (helper, cytotoxic & regulatory T cells)
- Also augments Ig synthesis by B cells and increases killing by NK cells.
- Antagonized by TGF-beta
What are the two signals necessary for a macrophage to become activated and kill intracellular pathogens? What are these signals provided by?
IFN-gamma and CD40ligand (CD154)/CD40 interactions. These signals are provided by the Th1 lymphoctye. Macrophages has the CD40 receptor and the T lymphocyte has the CD40 ligand (CD154).
Membrane bound cytokines. Describe and name 3.
Membrane bound cytokines remain on the cell surface of a cell. Because they are membrane bound, two cells must be close in proximity so the ligand and receptor can interact. Ex) CD40 ligand (CD154), TNF, Fas ligand (CD178).
CD40
This is the receptor for the membrane bound cytokine CD40 ligand also called CD154.
Interaction between CD40 and CD40 ligand/CD154 is required for Ig isotope switching in B lymphocytes.
X-Linked Hyper IgM Syndrome
Caused by loss of CD40 ligand (CD154) or loss of signal between CD40 and CD40 ligand. Results in high IgM levels and almost no IgG, IgE, or IgA. Patients cannot respond to thymus dependant disease.
Autoimmune Lymphoproliferative Syndrome (ALPS)
Caused by loss of receptor for Fas ligand (CD178). These patients have swollen secondary lymphoid organs because they cannot remove lymphocytes after an immune response.
Colony Stimulating Factors
These cytokins enhance growth and differentiation of cell types.
- IL-3: causes growth and differentaitiation of all progenator cells of all lineages
- Granulocyte (G-CSF): neutrophils
- Mactophage (M-CSF): monocytes
- GM-CSF: granulocytes and monocytes
- IL-7: T and B cell development
Proinflammatory Cytokines
- Secreted by macrophages
- TNF, IL-8, IL-1, IL-6, IL-12
TNF-alpha
- Secreted by macrophages
- Increases the permeability of blood vessel endothelium
- Mediates septic shock: increased permeability of vascular endothelium, causes leukocyte recruitment
- Responsible for CHACHEXIA
IL-8
- Secreted by macrophage
- Chemokine that ATTRACTS NEUTROPHILS
- (“Clean up on aisle 8”)
IL-1
- Secreted by macrophage
- Causes FEVER
- Causes ACUTE INFLAMMATION
- Activates endothelium to express adhesion molecules
- Induces chemokine secretion to recruit leukocytes
- Along with IL-23 causes differentation of Th17 cells
IL-6
- Causes FEVER
- Stimulates release of ACUTE PHASE PROTEINS from the liver during inflammatory response
- Secreted by macrophage and Th2
- Activates T and B cell differentiation into plasma cells
IL-12
- ACTIVATES NK cells
- Secreted by macrophages and B cells
- Induces NK production of IFN-gamma
- Along with IFN-gamma, STIMULATES DIFFERENTIATION Th1 cells
IFN-gamma
- Secreted by Th1, macrophages, NK, and cytotoxic T cells
- Inhibits differentiation of Th2 cells
- Causes virally infected cells to be more susceptible to killing by INCREASING MHCI & II expression on cells
- Has anti-tumor properties
- INCREASES RESISTANCE of unaffected cells to infection by stimulating production of ribonuclease than inhibits viral mRNA production
- Along with IL-12, results in differentiation of Th1 cells
IL-4 from macrophages
- STIMULATES IgE production
