CHP 4 - Adaptive Immune System Flashcards
Which receptor on the T cell is responsible for recognizing pathogens?
T-cell Receptors
T/F: T-cell receptors are transmembrane proteins
True
T-cell receptors are heterodimers and can consist which chains?
1) alpha and beta
2) gamma and delta
In order to T-cell receptors for recognize antigen, they must attached to which molecule? – a receptor found on other cells
MHC molecule
MHC I binds/interacts with which T-cell substype?
CD8+
MHC II binds/interacts with which T-cell subtype?
CD4+
MCH I can be found on which cells?
All nucleated cells
MHC II can be found on which cells?
Antigen presenting cells ( immune cells)
Elaborate which cells of the innate immune system will have MHC II?
1) Macrophages
2) Neutrophils
3) Dendritic cells
MHC I presents peptides that have been degraded from _______ the cell
Inside
MHC II presents peptides that have been degraded from _______ the cell
Outside
CD8 + T cells express a receptor that recognizes antigen presented by which MHC class molecule?
MHC I
CD4 + T cells express a receptor that recognizes antigen presented by which MHC class molecule?
MHC II
CD8 coreceptor binds to the ____ chain of the MHC class I
alpha
CD4 coreceptor binds to the ____ chain of the MHC II class molecule
Beta chain
What is the basic immunoglobulin structure?
2 heavy chains, 2 light chains held by disulfide linkages
T/F: immunoglobulins have 2 identical binding sites?
True
Which region of immunoglobulins is responsible for forming a single antigen binding site?
Variable region of the heavy chains and light chains
What are the five major functions of soluble immunoglobulins?
1) Neutralization of foreign particles or pathogens
2) Opsonization – increases phagocytosis
3) Complement activation – classical pathway activation of complement system
4) Activation of innate immune cells – due to phagocytosis and complement system enhancement
5) Protection of internal mucosal surfaces
Why does the adaptive immune system require several days to two weeks to respond to new pathogen?
1) Receptor diversity – somatic recombination
2) Antigen presentation and migration
3) Proliferation and differentiation of antigen specific B cells and T cells
CD8 T cells engage with class _____ MHC and differentiate into ____________.
I ; cytotoxic
CD4 T cells engage with class ___ MHC and differentiate into _____________.
II ; Helper T cells
What is the function of a Helper T cell?
Stimulate B cells to proliferate and differentiate into memory B cells and plasma B cells
Somatic recombination only occurs in __________ T cells and B cells
Developing
Which segments during somatic recombination are spliced and recombined in the alpha T cell receptor and light chains of an immunoglobulin?
V and J
Which segments during somatic recombination are spliced and recombined in the beta chain of a T cell receptor and heavy chains of an immunoglobulin?
V, D, and J
What are the two different types of light chains in immunoglobuolins?
K (Kabba) and Lamda
Heavy chain of an immunoglobulin has which recombination segments?
V, D, and J
The light chains of an immunoglobulin has which recombination segments?
V and J
T/F: Each B cell can express immunoglobulin with different light chains (Kabba and Lamda)
False; must be the same light chain
Kabba and Kabba or Lamda and Lamda
Recombination of lymphocyte genes requires the action of VDJ recombinase through ________ enzyme which recognizes _______ at different gene segments
RAG; RSSs
How does diversity occur at the joints? (after RAG1/RAG2 cleave VDJ segments?
1) addition of P-nucleotides in single strand overhangs
2) Deletion of nucleotides
3) Addition of random nucleotides called N-nucleotides
4) Junctional sequence diversity amplifies receptor diversity
Which enzyme is responsible for adding P-nucleotides on single strand overhangs?
Artemis
Which enzyme is responsible for deleting nucleotides?
Exonuclease
Which enzyme is responsible for the addition of random nucleotides called N-nucleotides?
(TdT) Terminal deoxynucleotydil transfersase
What mechanisms result in T cell and B cell receptor diversity?
T cell and B cells
1) Multiple gene segments - V(D)J
2) Templated nucleotide addition (P-nucleotide addition)
3) Deletion of nucleotides - exonuclease trimming
4) Non templated nucleotide addition (N-nucleotides)
ONLY B cells
Combination diversity of light chains with heavy chains
Which self tolerance mechanism is responsible for selecting cells with functional receptors?
Positive selection
Which self tolerance mechanisms is responsible for terminating cells with high affinity to self-receptors?
Negative selection
When a lymphocyte lacks membrane receptors that recognize antigen it dies by ?
Neglect
Lymphocytes with functioning MHC receptors are ___________ selected to continue their development
Positively
Lymphocytes that are too likely to recognize self-antigen are ____________ selected and die by apoptosis
Negatively
To prevent circulation of self-reactive lymphocytes, receptors are tested for binding affinity to self-antigen. This type of selectivity is also known as?
Negative selection
Developing lymphocytes are tested for their presence and binding capacity of their receptor. This type of selectivity is known as?
Positive selection
What are the steps of MHC class I peptide presention?
1) proteins in cytoplasm digested to peptide fragments via proteasome
2) transportation of peptide fragments to ER and loaded to MHC I
3) Class I MHC peptide complex exits ER and travels to plasma membrane
4) Recognition of MHC I peptide complex from CD8 T cell
How does MHC I peptide complex travel to the plasma membrane?
Through secretion pathway via vesicles to the Golgi complex and eventually to the plasma membrane
What are the steps of MHC II peptide complex presentation?
1) Synthesis of MHC II molecule at ER - inactive state
2) Transportation of inactive MHC II molecule to Golgi complex through secretory pathway via vesicles and wait for fusion with phagolysosome
3) Recognition of extracellular pathogen and phagocytosis
4) Fusion of phagolysosome and vesicle containing MHC II molecule – now active
5) transportation of MHC II peptide complex to plasma membrane
6) CD4 T cell recognition
T cell receptors associate with other transmembrane proteins that form the _____
CD3 complex
What do naive B cells initially secrete? (type of immunoglobulin)
IgM
Naive B cells have cell which subtype of immunoglobulins on its cell surface?
IgM and IgD
Give reasons as to why the primary immune response requires time
1) antigen recognition and processing
2) migration of dendritic cells to lymph nodes
3) T cell presentation
4) activation and differentiation of T cells and B cells
What needs to occur for the CD3 complex of a T cell receptor to change structure and send signaling motifs?
Phosphorylation
All CD8 T cell’s become into cytotoxic T cells when exposed to an antigen. However, CD4 can become into other T cells. What are these effector T cells?
1) NK T cells
2) TH2 - Helper T cell
3) Th17 - activates neutrophils
4) Memory T cells
5) Regulatory T cells – induces tolerance
Which proteins are associated with B cell receptors and have cytoplasmic domains with signaling motifs?
Ig-alpha and ig-beta
Ig-alpha and Ig-beta signals B cells to?
differentiate into antibody secreting cells (plasma cells)
