Adaptive Immunity Part 1 Flashcards
Adaptive immunity is considered nonspecific/specific (Choose one).
Specific!
Adaptive (acquired, specific immunity) makes up the ___ line of defense. What cells are involved in this line of defense?
Third; Specialized lymphocytes (T & B cells) & plasma cells (antibody factories)
What are the 2 types of adaptive immunity, their primary cells, and their location of action?
- Antibody-mediated (aka humoral) adaptive immunity - B cells, plasma cells, and circulating antibodies; directed against extracellular pathogens
- Cell-mediated adaptive immunity - T cells; directed against extracellular pathogens, cancer cells, & transplanted tissue
T/F Both arms of adaptive system, antibody and cell mediated, produce memory cells.
T
Helper T-cells may trigger activation of which cells?
Both T and B cells
Given that human cells contain only about 35,000 genes, how could a billion (10^9) or more different antigen receptors (epitopes) possibly be generated?
a process called genetic recombination = diversity of antigen receptors in both B cells and T cells is the result of shuffling and rearranging a few hundred versions of several small gene segments
- these gene segments are put together in different combinations as the lymphocytes are developing in bone marrow and thymus
T/F Before a particular antigen ever enters the body, T cells and B cells that can recognize and respond to that intruder are ready and waiting.
T
An amazing feature of the human immune system is its ability to recognize and bind to at least _____ different epitopes.
a billion (10^9)
____ = antigen receptors in B cells and T cells
epitopes
What are the 2 phases of the adaptive immune response?
- Generation of Clonal Diversity
- Clonal Selection
What is produced from the Generation of Clonal Diversity?
Production of immunocompetent, naïve T and B cells with all possible receptors for antigen (diverse receptors for 10^9 antigens)
Where does generation of clonal diversity take place?
Takes place in the primary/central lymphoid organs:
- Thymus for T cells
- Bone marrow for B cells
During maturation in generation of clonal diversity, B cells gain _____, and T cells gain _____. This results in: ______
- antigen receptor molecules (BCRs = B-cell receptors)
- receptors called T-cell receptors
- immunocompetent but naïve T and B cells
Where do immunocompetent T and B cells go after maturation in the primary lymphoid organs?
T and B cells migrate to secondary lymphoid organs (spleen and lymph nodes) to wait for antigens
When does generation of clonal diversity occur?
During fetal life
T/F No foreign antigen is involved in generation of clonal diversity.
T
What is meant by “immunocompetent but naïve” cells?
Cell is ready to meet antigen but has not met it yet
When does clonal selection occur?
At birth and proceeds throughout life
What are the 3 processes of clonal selection?
- Selection,
- Proliferation,
- & Differentiation of…
…individual T and B cells with receptors for a specific antigen
What initiates the clonal selection process?
T and B cells (in the secondary lymphoid organs) are ‘presented’ an antigen
Where are the B and T cells as they wait to be presented with an antigen during the clonal selection process?
In the secondary lymphoid organs (spleen and lymph nodes)
What are the results of clonal selection?
- Expansion of the population (cloning)
- Differentiation into antibody-secreting plasma cells or mature T cells or both
What are the final products of clonal selection?
Plasma cells that produce antibodies
Effector T cells (helper T cells, cytotoxic T cells, regulatory T cells)
Memory B and T cells
Where does B-cell maturation occur? Which process of adaptive immunity is B-cell maturation a part of?
- Bone marrow
- Generation of clonal diversity
To which secondary lymphoid tissue do mature, immunocompetent B cells migrate to after generation of clonal diversity?
lymph nodes
Which surface antibodies are expressed on mature B cells?
surface IgM (macro-globulin) and IgD
Changes during B-cell maturation include:
1. ___
2. ___
3. ___
- development of BCRs (antigen receptor molecules)
- expression of surface antibodies (IgM and IgD) & other surface proteins (CD21 - a complement receptor)
- Negative feedback via clonal deletion
Surface markers on mature B cells include:
- CD21 - a complement receptor
- Antibody anchored to PM (IgM & IgD)
All of the surface antibodies on an individual B cell are ____ for the same antigen
Specific!
A(n) ____ initiates clonal selection.
antigen
The ____ cell membrane has a more complex array of proteins than _____ cells.
T; B
What does the T-cell membrane consist of and what are the functions of its components?
Consists of:
- Antibody-like transmembrane protein (TCR = T-cell receptor) - responsible for recognition and binding to specific antigen by serving as an antigen receptor on surface of T cells
- Accessory proteins for intracellular signaling
Antigen receptors on the surface of T cells, called T-cell receptors (TCRs), recognize and bind to ____ foreign antigen fragments that are presented in _______ complexes from the ____.
- specific
- antigen-MHC Class II
- Antigen Presenting Cell (APC)