Exam Three Flashcards
What are the molecules used by Tc cells to induce apoptosis of the target cells?
fas-L, granzyme, and perforin
What is the first event that triggers an adaptive immune response?
The interaction of a naïve T cell with an APC cell.
CD28 and/or ICOS provide costimulatory signals to _____
naive T cells
What characteristics do TI antigens have?
The characteristics of both bacterial cell wall components and capsular polysaccharides
Which immunoglobulin isotype CANNOT be produced by memory B cells?
IgM
Which type of T cell is most important to regulate B-cell activity and differentiation?
Tfh
What kind of response is provoked by protein antigens regarding B-cell responses?
TD (T-cell dependent)
What are the effector molecules of humoral immunity?
Dendritic cells
What type of immunoglobulin is able to protect the fetus by crossing the placenta?
IgG
Where do Naïve CD4+ and CD8+ T-cells leave to enter circulation?
the thymus
What type of immunoglobulin are good at agglutination?
IgM
What peptides do TH cells recognize?
MHC class II -peptides
What type of immunoglobulin is able to protect the newborn baby through breast milk?
IgA
True or False: Memory cells provide an almost immediate response upon subsequent exposure to a specific pathogen
TRUE
True or False: T-independent antigens are rarely carbohydrates
FALSE
What type of immunoglobulin can cause degranulation of mast cells?
IgE
True or False: MHC tetramers are a novel way to detect and follow specific T-cell populations.
TRUE
What regulates allergic reactions?
Treg cells
Which Ab has the most potent roles in inducing allergy and immunity to worm infections?
IgE
Which Th cell subset is MOST likely to be generated in response to coronavirus infection?
Th1
Which T helper cell type inhibits inflammation?
Tfh
What is the first immunoglobulin isotype produced during the course of a primary immune response?
IgM
Which Ab has the biggest molecular weight?
IgM
What is a naive T-cell?
a T cell that has not yet encountered an antigen
Which class of antibodies is good at fixing complement?
IgG
Polarizing cytokines: IL-12
Master gene regulator:
T-bet
Polarizing cytokines: IL-6 and TGF-beta
Master gene regulator:
RORgammat
Polarizing cytokines: IL-2 and TGF-beta
Master gene regulator:
FoxP3
Polarizing cytokines: IL-6 and IL-21
Master gene regulator:
Bcl-6
What is MHC I’s signaling counterpart?
CTL-TCR
What is MHC II’s signaling counterpart?
TH-TCR
What is IgG’s signaling counterpart?
FcyR
What is CD28’s signaling counterpart?
B7-1 or B7-2
What is a Superantigen’s signaling counterpart?
TCR/MHC II
Superantigen
Viral and bacterial proteins that bind to specific Vβ regions of TCRs and α chain of class II MHC molecules
Costimulatory signal
The signal required to induce proliferation of antigen-primed T cells, generated by interaction
of CD28 on T cells with CD80/86 on antigen-presenting cells.
Extravasation
Movement of leukocytes through an unruptured vessel wall into the surrounding tissue at sites of inflammation.
GC dark zone
The portion of the germinal center densely packed with proliferating B cells
high-endothelial venules (HEVs)
the location where lymphocytes exit the bloodstream and enter directly into a lymph node
Affinity maturation
the increase in average antibody affinity for an antigen that occurs during an immune response and later, same-antigen exposures
Ig class switch recombination
Process in the GC where the constant regions on proliferating B cells’ Ig heavy chain can switch from expressing one class of Ig to another.
Neutralization
An antibody-mediated effector function that protects against viral/bacterial infection and the damaging effects of toxins
Adjuvants
Factors added to a vaccine to enhance immune response by activating innate immune cells
Complement fixation
The process of binding serum to the product formed by the specific antibody and antigen of the serum complement bound together.
Explain how CTL cells recognize infected cells and the mechanisms used by CTLs to kill the target cells
Cytotoxic T lymphocytes recognize infected cells by activating TCRs and killing the target cells by making a CTL-target cell conjugate and using cytoplasmic rearrangement, leading to granule exocytosis which causes the target cell to go through apoptosis. The way of initiating this apoptosis can be through directional delivery of cytotix proteins or interaction of membrane-bound Fas on CTLs and surface Fas on target cells.
Explain how TH1/TH2 cells cross-regulate one another.
Cytokines assist with this cross-regulation. IFN-γ (Th1) inhibits IgG1/IgE class switching (Th2). IL-4 (Th2) inhibits production of IgG2a (Th1). Master regulators T-bet and GATA3 commit T cells to one subset and against the other. T-bet supresses Th2 pathway gene expression, and GATA3 suppresses the same for Th1.
NK cells do not express TCR, yet bind to class I MHC molecules on potential target cells. Explain how NK cells lacking TCRs can specifically recognize virally infected cells?
NK cells recognize virally-infected cells using the missing self model. Normal cells will present a ligand for the activating receptor on NK cells as well as a MHC class I ligand for the inhibitory receptor. The balance of these inhibitory and activating signals produced determines if the NK is activated or not.
Suppose you are using a mouse strain that lacks GATA-3 gene (GATA-3 deficient mice) to do experiments and you find that this mouse has a difficult time clearing helminth (worm) infections. Why might this be?
GATA-3 is the master gene regulator that produces the cytokine IL-4 which is known to prevent worm infection through eosinophil activities. Therefore, this mouse probably has a hard time because there is no immune defense against the worms.
