Antigen Recognition by T Cells Flashcards
What is the reactive lymphocytes in the blood during mononucleosis caused by epstein barr virus?
T cells, not B cells
EBV is a persistent and chronic infection of (blank) cells
B
The CTLs recognize EBV proteins located (intracellular/extracellularly) of chronically infected B cells
intracellularly (in the nucleus)!!!
There are (blank) major types of T cells and their roles
6
T cell receptors are (blank-beta) or (gamma-(blank) chain dimers
delta
CD (blank) is on all T cells
3
T cells are (always resting/active) until antigen stimulated
resting until stimulated
When do T cells proliferate?
upon antigen stimulation, then able to mediate functions
How long do T cells last?
a lifetime
Do memory T cells act quickly when re-stimulated by an antigen?
no, they must be restimulated, proliferate, then they can mediate functions
What are the 6 T cell subsets?
4 types of CD4 T helper cells -TFH -TH1 -TH2 -TH17 AND CD4 T regulatory cells AND Cytotoxic T cells CD8
What does TFH (follicular helper) do?
cells produce growth factors for B and T cells
What does TH1 do?
increases cytotoxic T cell activity
What does TH2 do?
increases antibody production; switch to IgE
What does TH17 do?
brings neutrophils to site
What does CD4 T regulatory cells do?
regulate proliferation of normal T and B responses
suppresses autoimmunity
What do cytotoxic T cells CD8 do?
kill cells infected with viruses
Where do you find follicular helper T cells?
you find these CD4 T cells in lymphoid follicles in spleen, lymph nodes peyers patches (small intestine)
How do follicular helper T cells divide?
they must recognize and antigen then they can divide
What is the function of follicular helper T cels?
provide cytokines required for T and B cell proliferation and are used for memory
What do follicular helper T cells produce?
IL-2 (a growth factor for all T and B cells) IL-4, IL-5, and interferon g
If you lack CD4 T helpers what can you leave your self susceptible to?
getting AIDS!!!!!
(blank) cells support T cell division and direct B cell functions
TFH CD4 T cells
Why is the loss of CD4 T helper cells critical in the development of AIDS?
This decline will result in a decline and loss of IL-2 secretion and thus T/B cell activation and proliferation.
Where do you find TFH in the spleen?
in the periarteriolar lymphoid sheath
What does CD4 Th1 secrete?
gIFN (mainly) and IL-2
What does CD4 TH2 secrete?
IL-4 and IL-5 and IL-2
Where do you find B cells in the spleen?
in the germinal center
What is the main function of CD4 Th1 cells?
activate infected macrophages, provide help to B cells for antibody production, support CD8 cytotoxic activity
What is the main function of CD4 TH2 cells?
provide help to B cells for antibody production, especially switiching to IgE
How can you differentiate between CD4 TH1 and TH2?
different cytokine production and TH1s support CD8 cytotoxic activity
TH1 and TH2 can (blank) the immune response.
polarize
TH1 and TH2 can polarize the immune response, what does this mean?
meaning that depending on which TH cell is activated the immune response can be driven more cellularly (via Th1 response) or more humoral (via the Th2 response).
(blank) is the signature cytokine that distinguishes a TH1 cell from TH2 and TH17 cells
Gamma interferon
(blank) is the signature cytokine that distinguishes a TH2 cell from TH1 and TH17 cells.
IL-4
(blank) is the signature cytokine of TH17 cells that distringuishes TH17 cells from TH1 and TH2 cells.
IL-17
TH1 responses drive (blank) immune responses
cellular (main goal is to make cytotoxic granules)
TH2 responses drive (blank) immune responses
humoral
i.e main goal is to make antibodies
T or F
many different cell types have receptors for gamma interferon
T
Gamma interferon is the (type I/type II) interferon.
type II (i.e cannot use alph and beta interferon receptors)
Do B cells have receptors for gamma interferon? What does this mean?
yes
cause B cells to slow proliferation and to switch to IgG isotypes
What cell types have receptors for IL-4?
B cells and eosinophils
What does interferon gamma do?
IFNγ is an important activator of macrophages and inducer of Class II major histocompatibility complex (MHC) molecule expression
(blank) polarize T helper 1 or T helper 2 cell differentiation (and individual biases)
cytokines
(blank) from dendritic cells and macrophages direct conversion from TH0 (immature effector T cell) to TH1
IL-12
What releases IL-12 to allow from the conversion rom TH0 (immature effector T cell) to TH1
dendritic cells and macrophages
(blank) from ACTIVATED mast cells and TH2 cells directs THO conversion into TH2
IL-4
What releases IL-4 to direct THO conversion into TH2?
activated Mast cells and TH2 cells
(blank) control intracellular mycobacterium tuberculosis that cause TB, which is unaffected by Ab’s
TH1 T cells
How does THI T cells control TB?
beating it up intracellularly
Mycobacterium tuberculosis prevents formation of (blank)
phagolysosomes
How do delayed type hypersensitivity T helper 1 cells kill bacteria?
it uses gamma interferon to instruct macrophages to kill bacteria inside the macrophages
What are delayed type hypersensitivity TH1 cells?
these are memory TH1 cells that were previously sensitized to the antigen, proliferated and became quiescent memory cells until they re-encountered their cognate antigen
Are delayed type hypersensitivity responses (DTH) quick?
no they take about 48 hours
What happens around 18 hours in the DTH response?
you get leakage of plasma into the skin site and fibrinogen is activated to fibrin.
In the DTH response when you get leakage of plasma into the skin and this is coupled with fibrin, what happens?
You get induration which is when a FIRM lesion forms
When does induration peak?
24-48 hrs after antigen introduction
What happens to macrophages when under the influence of TH1?
they become multinucleated
Memory TH1 cells take how long after activation to make gamma IFN? When does the macrophage response occur?
more than 4 hours
hours after this response
When macrophages are induced to multinucleate by TH1 cells, what else do they do?
Make TNF alpha and other inflammatory cytokines and then make the skin response
NOTE::::: Macrophages make the skin response!!!!
What are the 2 essential cell types in DTH?
macrophages and TH1 T
What are memory CD8 T cells?
they are cells that when activated again will release granulysin which kills intracellular bacteria.
What does granulysin (the cytotoxin released from CD8) need to enter infected cells so they an kill stuff?
perforin
What are some examples of DTH immunopatholoy type IV responses?
poison ivy and nickel allergies (these are memory responses)
Control of TB bacteria; elimination of other bacteria is done by what?
CD4 TH1 and DTH
Long term control of TB and clearance of intracellular bacteria is done by what?
CD8 and CTL (w/ perforin and granulysin)