2.7 - Cell Mediated Immunity Flashcards
___ is the most important primary immune response
Dendritic cells
Dendritic cell function
Process antigen material and present it on the cell surface to T cells, especially in a primary response
Once T cells leave the thymus, they populate
Secondary lymphoid organs
Majority T cells express the ___ T cell receptor
alpha:beta receptor
T cells leave thymus as
Mature naive T cells
Effector cells
Mature naive T cell that has interacted with antigen on DC
Cytotoxic CD8+ location, antigen recognition, and effector action
- Cytosol
- MHC class I
- Killing of infected cell by apoptosis (cytotoxic T cell)
CD4+ TH1 location, antigen recognition, and effector action
- Macrophage vesicles
- MHC class II
- Activation of infected macrophage by cytokines
Class I molecules are located
All cell types, except RBC
Class II cells are located where
On APC (B cells, macrophages, dendritic cells)
What is an immature dendritic cell called?
Langerhans’ cells
Where can you find langerhans’ cells?
In the epithelial area of mucosal surfaces and skin
When do langherhans’ cells become dendritic cells?
When they enter the lymph node to become DC expressing B7
Mature DC can ___ antigens but ___ process
Present antigens but CAN’T process
Immature DC ___ process but ___ present
Can process but can’t present
T cells that don’t encounter specific antigen leave the lymph node in the ___
Efferent lymph
How do naive T cells enter the lymph node?
Across high endothelial venules in the cortex, in the blood or lymph
In the blood T cells interact w/ endothelium cells via ___ expressed by T cell and endothelium cell
Adhesion molecules
Steps for T cell entering lymph node
- T cell enters high endothelial venule (HEV)
- Binding of L-selectin to GlyCAM-1 and CD34 allows rolling
- LFA-1 is activated by chemokines
- LFA-1 binds to ICAM-1
- T cell enters lymph node between 2 endothelial cells (diapedesis)
What are important adhesion molecules?
Intergrin LFA-1 and it’s ligand ICAM-1
Adhesion molecules allow for what?
TCR to come in contact w/ the process antigen associated with the MHC
What are the signals involved in the activation of T cells?
- Signal 1 = MHC & TCR and co-receptors CD4 or CD8
- Signal 2 = co-stimulators B7 on APC and CD28 on the T cell
If the T cell recognized a self antigen, then the T cell would become ___. What does the APC not have?
Anergic
APC doesn’t have co-stimulator molecule (B7)
What does it mean if there is a co-stimulatory signal alone?
- T cell didn’t recognize antigen
- No effect on T cell
Once the T cell becomes anergic, what happens?
It will remain active b/c it may encounter a specific antigen w/ appropriate co-stimulators
T cell + dendritic cell proliferation leads to
Activated T cells and memory T cells
IL-2 receptor is called
CD25
High affinity of IL-2 is the result of the IL-2 receptor formation. What is the receptor composed of?
gamma, beta, and alpha
When the T cell is activated, it expressed high affinity for CD25, which interacts w/ CD25 produced by the same cell. This is called ___, which leads to
Autocrine effect
Leads to T cell proliferation
General question: cytokines have what 3 types of effects on cells?
Autocrine
Paracrine
Endocrine
What are the 4 different types of cytokine effects on cells? Describe each one.
- Pleiotropy - same cytokine can do different things
- Redundancy - certain cytokines do the same thing
- Synergy - 2 cytokines work together to cause effect
- Antagonism - 1 cytokine might prevent activity of another
What are the CD4+ T cell subsets?
CD4-TH1 and CD4-TH2
Cytokines include ___ and ___
Lymphokines and interleukins
CD4-THone cytokines
IL-2, gamma interferon (IFN-gamma)
CD4-TH2 cytokines
IL-4, IL-6, IL-10, IL-13
CD4-Treg cytokines
TGF-beta, and IL-10
CD4-TH1 cytokines are associated w/ ___ immune response
Cell mediated
- Intracellular pathogens
CD4-TH2 cytokines are associated w/ ___ immune response
Humoral
- Extracellular pathogen
CD4-Treg cytokines are associated w/ ___ immune response
- downregulation of immune response
CD4-TH17 cytokines are associated w/ ___ immune response
autoimmunity and inflammation
CD4-TH17 cytokines
IL-17
CD4-TH1 is inhibited by
IL-4 and IL-10
CD4-TH2 is inhibited by
IL-12 and IFN-gamma
Steps for CD4-TH1 killing cell
- TH1 recognizes antigen in class II and releases gamma interferon (cytokine)
- gamma interferon further activates macrophage, which enables it to kill the cell
Examples of CD4 response based on how it’s activated
Tuberculoid leprosy (in TH1)
Lepromatous leprosy (in TH2)
Describe tuberculoid leprosy
- low infectivity
- Granulomas and local inflammation (low antibody response)
- normal serum immunoglobin levels
- in TH1
Describe lepromatous leprosy
- high infectivity
- disseminated infection
- hypergammaglobulinemia (high conc. of antibodies don’t have affect on org.)
- in TH2
What are considered pro-inflammatory cytokines in TH1?
TNF-alpha and IFN-gamma
What are considered pro-inflammatory cytokines overall?
TNF-alpha
IFN-gamma
IL-1
IL-6
IL-8
IL-12
IL-17
IL-8 is known as a ___
Chemokine
What do each activated TH1 cell do?
- IFN-gamma = activates macrophage to destroy bacteria
- TNF-alpha = helps diapedesis
- IL-2 = pro-inflammatory cytokine
CD8 T cells can produce IL-___ but may also depend on CD4-T___ production
IL-2
CD4-TH1 production
Steps for activation of CD8
- stimulation of naive T cell w/ co-stimulatory signal, MHC I, TCR, antigen
- Proliferation from release of IL-2
- Differentiation
- Effector T cell activated, leaves lymph node to go into blood to interact w/ microorg. it’s programmed for
Does CD8 have the co-stimulators attached once it’s turned into an effector T cell?
No
NK cells kill by production of ___ and release of ___
production of perforin
release of granzymes
NK cells specific or non-specific
Non-specific
What does perforin do?
Polymerizes to form a pore in target membrane
- allows protein into cell
What does granzymes do?
- activate apoptosis in cytoplasm of target cell
- perforin allows granzymes in
Why don’t you do cell lysis w/ CD8 cells?
b/c you won’t want contents to be released into cell and infect it
CD8 ___ granules after killing first cell and moves on to kill another
regenerates
