Exam 2: Dr. Pharr Principles of Adaptive Immunity Flashcards
What is adaptive immunity’s focus?
Defense mechanisms onto the pathogen itself
What do lymphocytes of adaptive immunity express?
Antigen receptors that recognize specific features of a microorganism
What does the recognition of specific features of microorganisms allow the adaptive system to do?
Distinguish between different microorganisms
What is immune memory?
A second encounter with the same pathogen that will induce a more rapid and efficient adaptive immune response
How do effector cells eliminate pathogens from the body?
Effector function
What is a pathogen?
A microbe that has a disease causing function or antagonist to the animal
Why are all non-self microbes harmful?
They can replicate
What is a B cell receptor referred to as?
Immunoglobulin
What are the soluble forms if B cell receptors referred to as?
Antibodies
What does the surface of T lymphocytes/cells express?
T cell receptor
What are the regions that make up B cell and T cell receptors?
Variable region
Constant region
What happens in the variable region?
Antigen binding
What does the constant region do?
Anchors the receptor to the cell membrane
What does the constant region determine when the BCR is secreted as an antibody?
The effector function of the antibody
Where do B cells develop? T cell?
Bone marrow
Thymus
What do antigen receptors recognize?
Protein, carbohydrates, and lipids
Self-proteins, self-carbohydrates, and self-lipids
Why do B cells and T cells recognize different forms of the same antigen?
Because of their particular effector functions
What do BCRs recognize?
The native form of an antigen
What do TCRs recognize?
Peptides derived from the proteolytic degradation of the antigen
Where does T cell recognition of antigen occur?
Secondary lymphoid tissues
Where are dendritic cells present?
In the tissues with macrophages
How do dendritic cells activate adaptive immunity?
In a situation where the innate response is overwhelmed, DCs engulf the pathogen at the site of infection and migrate in afferent lymphatic vessels to lymph nodes
Where do DCs enter? Where do the migrate to?
Enter lymph node
Migrate to the capillaries where lymphocytes enter
Because DCs enter the lymph node and migrate to capillaries, what can naive T cells do?
Enter the lymph node and survey the antigens displayed on the surface of DCs
What does antigen do?
Causes specific T cells to be activated to proliferate and then differentiate into effector T cells
After T cells have been differentiated into effector T cells due to antigen, what happens to effector T cells?
Migrates to the lymph node to the site of infection and display their effector function
What are the effector functions of effector T cells?
Activate macrophages to kill pathogens that have been taken up by phagocytosis (helper T cells)
Kill infected cells (cytotoxic T cells)
Where are the 2 zones of the lymphocyte? Where are the zones located?
B cell zone–located in the medulla
T cell zone–located in the outer cortex
What do some of the effector T cells (helper T cells) remain in the lymph node for?
To provide activation signals to antigen specific B cells
What do DCs do?
Antigen processing
Antigen presentation
What is the major histocompatibility complex (MHC)?
A complex of immune system genes that encode membrane potentials which are involved in presenting peptides to T cells
What do T cells recognize? How?
An infection
By detecting peptide fragments derived from the pathogen
What happens to the peptides recognized by T cells?
They are captured by MHC proteins and expressed on the surface of cells
What are MHC proteins like?
They have a broad specificity and can bind peptides derived from many different pathogens
Where is MHC class I expressed?
On the surface of most nucleated cells in the body
What is MHC class I recognized by?
Cytotoxic T cells which express the co-receptor protein CD8
Where is MHC class II expressed?
On the surface of DCs, macrophages, and B cells
What is MHC class II recognized by?
Helper T cells which express the co-receptor protein CD4
What is the function of MHC class I proteins in protection against intracellular pathogens?
Many proteins in a cell are degraded into short peptides after performing their function and pumped into the endoplasmic reticulum
What happens to peptides in the ER?
They are bound by newly synthesized MHC class I protein and then transported to the cell surface
What happens to some of the viral proteins during a viral infection
They will be degraded in cytoplasm and transported to the ER for binding to MHC class I
Where are naive cytotoxic T cells activated?
Secondary lymphoid tissues by dendritic cells
What do effector cytotoxic T cells do after activation?
Enter the circulation and are recruited to the site of viral infection
What is the effector function of cytotoxic T cells?
Recognize and eliminate infected host cells
What is the function of MHC class II proteins in protection against extracellular pathogens?
Naive helper T cells are activated in secondary lymphoid tissue by DCs
Effector helper T cells are recruited to the site of infection and will activated the effector function of other leukocytes responding to the infection
What do effector helper T cells do to kill intracellular bacteria?
Activate macrophage production of powerful reactive oxygen species
What does antigen binding to the B cell receptor facilitate?
Internalization of the antigen for processing and presentation by MHC class II
What will activation of B cells by effector helper T cells induce?
B cell proliferation and differentiation to plasma cells
What do plasma cells do?
Synthesize and secrete the original antigen receptor as antibody
What are the 2 signals required for lymphocyte activation?
- Recognition of antigen
2. Delivered by another cell
What do antigen-activated T cells require a second signal from?
DCs
What do antigen-activated B cells require a second signal from?
Effector helper T cells
