Regulation of Adaptive Immunity (20 & 21) Flashcards
Why is it important to regulate the immune system?
mounting an immune response to both extremes can have consequences
excessive: autoimmunity, lymphoid tumors, amyloidosis, allergies
defective: increased infections, increased cancers
What is tolerance?
the unresponsiveness of immune system to antigens
Tolerance is primarily directed against _____ from normal tissues
self-antigens
What can become tolerant to an antigen if they encounter it early in fetal life?
immature lymphocytes
think of dizygotic twin calves example being able to tolerate skin grafts from each other
What is central tolerance?
thymocyte —> response within the thymus —> clonal deletion by apoptosis
What is peripheral tolerance?
low doses of antigen & lack of co-stimulation = anergy (body fails to react to antigen), apoptosis, or T-cell regulation
T/F: A self-antigen will produce an inflammatory response
FALSE - will not
T/F: Central T-cells react strongly with self-antigens
TRUE - will then undergo apoptosis
Where does central T-cell tolerance occur?
thymus
What is AIRE?
autoimmune regulator
transcriptional factor
Strong recognition of self-antigens by immature T-cells in thymus may lead to _____ or _______, or the development of regulatory T cells that enter peripheral tissues
negative selection or deletion
Lack of co-stimulation leads to _______
peripheral T-cell tolerance
The presence or absence of co-stimulation is a major factor determining whether T cells are _____ or _____
activated
tolerized
What is anergy in T cells?
refers to long-lived functional inactivation that occurs when these cells recognize antigens without adequate levels of co-stimulators that are needed for full T-cell activation
won’t die but won’t do anything either
If CD28/CD80 is blocked between the T cell and APC, it leads to _____
anergy
Anergy leads to _______
functional unresponsiveness
If the CD28/CD80 is blocked, there is engagement of ______
inhibitory receptors
leads to unresponsive (anergic) T-cell
Where are Treg cells made? What is the result?
thymus
lymph nodes
result: inhibition of T cell responses, inhibition of other cells
What is central B cell tolerance?
The presence of maternal antibody in a newborn animal effectively delays the onset of ______
antibody synthesis
in the absence of maternal antibodies, they will start to make antibodies immediately
Excess antibodies bind to ______ and results in a cross-linked antigen (is the same antigen)
CD 32
When T cell interacts with APC cell through TCR, you have expression of _____
Treg cells use a specialized transcription factor called ____
FoxP3
TH0 cells get a signal, _____ and _____, to use FoxP3 to make __________
retinoid acid
TGF-beta
to make suppressive cytokines (TGF-beta, IL-10, IL-35)
