Lymphocytes and their Receptors Flashcards
What types of lymphocytes are there? Of which are involved in the innate immune response?
T lymphocytes, B lymphocytes, and NK cells, which are the only ones involved in the innate response
What lymphocyte is associated with the cell-mediated immune response of the adaptive immune response?
T lymphocytes
What lymphocyte is associated with the humoral response of the adaptive immune response?
B lymphocytes
What cells are formed from a Pre-T cell?
T cells and NK cells
What is the difference between a memory cell and a plasma cell?
Memory cells = provide anamnestic response to secondary infections/ antigen reexposure
Plasma cells = terminally differentiated B cells that produce only a specific type of immunoglobulin
Where do Pre-T cells migrate, starting during fetal development?
The thymus
What cells are the precursors to thymocytes?
Pre-T cells
While thymocytes that produce a ______ chain become alpha-beta T cells, those thymocytes that produce what chain become gamma-delta T cells?
Alpha-beta T cells = Beta chain produced
Gamma-delta T cells = Gamma or delta chain produced
True or False: Complementarity between the antigen and the TCR dictates the specificity of a response.
True
Diversity of TCR components occurs in the ______, as a result of the random rearrangement of germline ____ _________.
Thymus
Gene segments
In TCR production, what chain is formed first - alpha or beta? Can it be expressed prior to the other chain’s completion
Beta chain, and no. It must wait until completion of the alpha chain for expression on the T cell surface
The V, D, J, and C regions of genetic material along a chromosome are not __________, meaning they are together in a uniform pattern.
Contiguous
What genes are transcribed and translated to form enzymes responsible for the reassortment of the V, D, J, and C gene segments in thymocytes?
RAG genes, or recombination activating genes
Explain how the beta chain is formed.
Random joining of the D-beta and J-beta gene segments via RAG proteins, that also bring in a V-beta segment to be joined with it as well.
Explain how the alpha chain is formed.
Joining of the V-alpha and J-alpha gene segments via RAG proteins, that is also joined with a C-alpha region segment
True or False: With the attachment of the C-alpha gene segment with the VJ-alpha segment, is the alpha chain variable region complete.
False, the variable region of the alpha chain is complete following the joining of V-alpha and J-alpha
Are RAGs associated with NK cell receptor production?
No, they’re not
While RAG proteins can cleave genetic material to form complete segments for alpha and beta chains, what enzyme is associated with excise the intervening DNA to increase the diversity of TCRs?
DNA-dependent protein kinase
What step takes place first, within the selection process of thymocytes in the thymus?
Positive selection
What is involved with positive selection?
Thymocytes are tested to see if their TCR’s can bind to MHC I or MHC II molecules on thymic APC’s
Where in the thymus does positive selection occur?
Cortex
What happens if a TCR fails to recognize and bind to a MHC I or MHC II molecules on thymic APC’s, due to a failure to produce a TCR or that its TCR is defective?
It is sentenced to death, via apoptosis
Following positive selection where to surviving thymocytes get tested on during negative selection?
Their ability to recognize MHC:antigen complexes
What causes a thymocyte to survive the negative selection process?
High affinity binding to Self peptide:MHC complexes and Antigen:MHC complexes
While alpha-beta T cells are MHC ________, gamma-delta T cells are MHC ___________.
Alpha-Beta = MHC dependent Gamma-Delta = MHC independent
Why are early thymocytes considered double negative?
They have neither a CD4 or CD8 coreceptor
When thymocytes do possess both CD4 and CD8 coreceptors, they are considered -?
Double positive
When a mature thymocytes has either a CD4 or CD8 coreceptor only, they are considered -?
Single positive
What occurs to thymocytes during positive selection, besides the binding of their TCRs to MHC molecules?
Their commitment to CD4 or CD8 lineages, based on their individual affinity to either MHC I or MHC II molecules (which they have to bind to to pass positive selection)
What happens to thymocytes to go from double positive to single positive?
It will turn or switch off the gene that is associated with the CD protein that is not associated with the MHC molecule that they have an affinity for
Following passage of both positive and negative selection, as well as commitment to be a CD4 or CD8 thymocyte, what will happen?
CD8+ thymocytes become cytotoxic thymocytes; whereas, CD4+ thymocytes become either helper thymocytes or regulatory thymocytes
What causes proliferation and differentiation of helper thymocytes to become Th1, Th2, or Th17 cells?
Antigen presentation
What gene allows for thymic epithelial cells to express many of the proteins usually found in other tissues of the body, which prevents the continuance of thymocytes that can react to self cells (which would be eliminated during negative selection)?
AIRE gene or Autoimmune Regulator gene
While B lymphocytes develop in either the _____ ______ or _________ _____, this process involves three stages - ________, _________ and ____________.
Bone Marrow or Cloacal Bursa
Maturation, Activation and Differentiation
These three sources - ___ ___, ______ _____, and _____ ______ - serve as areas for B lymphocyte __________, which is the generation of mature immunocompetent B lymphocytes as a result of differentiation from ________ precursor cells.
Yolk sac, fetal liver, and bone marrow
Maturation
Lymphoid
What must be present for Pro-B cells to mature into B lymphocyte precursor cells?
IL-7 and bone marrow stromal cells
Where is IL-7 produced?
In the bone marrow, and also by thymic stromal cells in the thymus
What effect does IL-7 have on IL-2 and its receptors?
It increases both the production of IL-2 and its receptors
True or False: The constant region is identical in all antibodies of the same isotype, but differs in antibodies of different isotypes.
True
What is the gene arrangement in maturing B cell receptors?
Germline to Dh to Jh, Vh to DhJh, and finally VhDhJh
What allows for only the expression of VLJL, kappa or lambda?
Allelic exclusion, where one alleles is expressed and the other is silenced
What causes a Pre-B cell to become an immature B cell?
Rearrangement of both the V, D, and J gene regions for the Heavy chains, and the V and J gene regions of the Light chains
The combination or grouping of both Ig-alpha/Ig-beta and IgM, forms a -?
B Lymphocyte Cell Receptor Complex (BCR)
Are BCRs of immature B cells functional? What happens if they happen to be stimulated?
No they are not, and if they are, they are eliminated or become unresponsive
What Ig’s are present on fully mature B lymphocytes?
IgM and IgD
A change in RNA coding of both heavy chains mu and delta, leads to -?
IgM and IgD expression, respectively
What is clonal deletion, and how does it apply to B cells?
Similar to negative selection, those B cells that have a high affinity for self antigens are eliminated
Mature B cells leave the bone marrow undergo activation and differentiation in the _________ to become plasma cells.
Periphery
B cell receptors have 2 identical ______ and 2 identical _______ chains. The _____ chains are bound to H chains by _______ bonds.
Heavy
Light
Light
Within the BCR complex, what portion serves as the signalling molecule?
Ig-alpha/ Ig-beta
What terminal end of the H chain is highly variable and associated with the distal portions of the chain?
N-terminal
What is the significance of the C-terminal end of the heavy chain in the BCR?
While expanding the cell membrane, it is identical for each BCR of that isotype
Which end of the light chain is more variable?
A) C-terminal
B) N-terminal
B) N-terminal
