Flashcards in Antigen Receptor and Lymphocyte Development Deck (32):
What is an antigen?
Antigen (Ag) is a molecule which specifically binds a T-cell receptor or an antibody (Ab) site
What is an immunogen?
Any molecule that elicits an immune response by binding to a T-cell receptor or an antibody
What are the specific immune receptors of the adaptive immune response?
T-cell receptors (TCR)
B-cell receptors (BCR)
These receptors are formed/generated to aid in immune response.
What are the preformed antigen receptors?
These act in the innate system. They are general, preformed antigens. NOT SPECIFIC.
What antibodies are displayed on mature B-cells?
When is the constant region spliced during Ig development?
During RNA processing
What creates diversity in the development of Igs?
TdT--transferase protein, adds nucleotides to the end before ligase proteins seal segments together.
TdT is present in which cells only?
Where do B cells mature?
Follicular region of lymph node
Where does a B cell become activated?
In the paracortex of a lymph node
Which region is combined first in Ig recombination?
RSSs contain how many base pairs?
12 or 23
What is an RSS?
Recombination Segment Sequence
Part of the V, D, J regions on genes for Igs
How many RSSs do V, D, and J have?
D: 2 (joins with both V and J)
What opens the hairpin loop to allow nucleotide addition to the immunoglobulin?
Artemis (protein enzyme)
Where do naive T-cells enter the thymus?
What guides T cells to the thymus?
CCR9 (receptor on thymocyte) + CCL25
Which chemokine is essential in bringing T cell precursors into the corticomedullary thymus?
What does CCR9 bind to?
Where is CCL25 produced?
The cortex of the thymus
Which chemokines guide the T cell from the cortex to the medulla during maturation?
CCR7 receptor (on thymocyte) + CCL21 and CCL19
Where do positive and negative selection of T cells occur?
When do T cells begin displaying CD3?
When they become DN3
When do T cells display CD25?
What does CD25 bind to?
When is a thymocyte committed to becoming a T cell?
After DN3 --> it is now displaying a TCR
What must happen for a T cell to finish positive selection and enter negative selection?
TCR must interact with self MHC. If it does not, apoptosis will occur.
Where do T cells become single positive cells?
What promotes the elimination of auto-reactive T cells in the medulla?
AIRE (auto-immune regulator protein-->transcription factor)
What drives negative selection of single positive T cells in the medulla?
What is CD44?
Adhesion molecule on thymocytes