Module 3 Flashcards
T cells
What is found on the surface of all T cells?
Cd3 complex
What are the 2 classes of T-cell receptors?
alpha-beta T cell and gamma-delta T cell
What 3 parts make up the T cell complex?
TCR, CD3, and zeta chains
What are zeta chains responsible for?
Signal transduction after TCR activation
What genes/proteins mediate variable region gene rearrangements for both TCR and antibodies?
RAG1 and RAG2
Which MHC has MHC encoded polypeptide and beta2-microglobulin and peptide binding grooves?
MHC I
Which MHC has two MHC encoded peptides and peptide binding grooves?
MHC II
Which class of T cells recognize peptides bound to MHC I and II?
alpha-beta T cells
Which T cells recognize MHC I and peptides?
CD8+ T cells
Which T cells recognize MHC II and peptides?
CD4+ T cells
Which MHC is expressed on most nucleated cells?
MHC I
Which MHC is expressed mostly on macrophages, dendritic cells, and B cells?
MHC II
MHC that processes and presents cytoplasmic proteins
MHC I
MHC that processes and presents exogenous proteins
MHC II
What trims peptides to fit the binding groove?
endoplasmic reticulum aminopeptidase (ERAP)
MHC locus in humans
HLA (human leukocyte antigen)
Which HLA regions are involved in CD8 T cell recognition and NK cells?
A, B, and C (class 1 region)
Which HLA regions are involved in Cd4 T cell recognition?
Dp, DQ, DR (class II region)
Where do MHC polymorphisms occur?
on the peptide binding groove
What is the expression pattern of MHC genes?
codominance
Which class of T cells does not need to bind to MHC
gamma-delta T cells
Where do T cell precursors originate?
bone marrow
Immature T cells
thymocytes
Disorder where the thymus fails to develop and T cells are absent. Pt susceptible to many opportunistic infections
DiGeorge’s Syndrome
What happens to T cells in older populations?
they involute (degenerate)
2 Stages of selection for alpha/beta T cells
positive and negative selection
What kind of T cell development occurs in the thymus?
antigen-independent
T cell selection that selects for recognizing MHC I or II
positive selection
T cell selection that selects for removal of T cells that bind too tightly to self antigens, including MHC
negative selection
What class of T cells leave the thymus once TCR has productively rearranged?
gamma-delta T cells
What kind of t cell can recognize bacterial products, and heat shock and stress proteins?
gamma-delta T cells
What kind of T cell development occurs in the secondary lymphoid tissues
antigen dependent
Self-reactive t cells that leave the thymus but are prevented from activation
peripheral tolerance
What can suppress self-reactive T cells?
T reg cells
Activation of which T cells leads to further development and differentiation into effector and memory cells?
naive alpha-beta cells
Where do naive T cells travel
between circulation and secondary lymphoid tissues
Where do effector and memory T cells travel
to potential sites of infection
What are the 3 types of antigen presenting cells
dendritic cells, macrophages, B cells
What are characteristics of APCs
present antigenic peptides on the MHC and express co-stimulatory molecules/cytokines
Antigen presenting cells carry antigens to where?
secondary lymphoid tissues
mediates first interactions between T cells and antigen presenting cells
CAMs (cell adhesion molecules)
What is needed for T cell activation
co-stimulatory signal
Specific co stimulatory molecule for T cell activation
B7
Molecule expressed by T cells after activation, then binds to B7 and competes with CD28 to shut down T cell activation
CTLA-4
B cell antigen recognized by B cell receptors
inducible B7
What happens when there are no co-stimulatory cells for T cell activation?
anergy (the cell shuts off basically)
Which Th cells are part of cell mediated immunity?
Th1
What cytokines are produced by Th1 and involved in cell-mediated immunity?
IFN-gamma, IL-2, TNF
Which Th cells are part of humoral immunity?
Th2
What cytokines are produced by Th2 and involved in humoral immunity?
IL-4,5,6
How do cytotoxic T cells kill cells?
Inducing apoptosis
These enzymes are contained in granules released from cytotoxic T cells
perforin and granzyme B
2 mechanisms of Cytotoxic CD8+ T cells to kill cells
- release lytic granules (perforin and granzyme B) and 2. FAS:FAS ligand interaction between target cells and cytotoxic T cells
