Hudig: Adaptive Immunology Flashcards
What are the 4 types of pathogens, and are they intracellular or extracellular?
- Bacteria - both
- Yeast and fungi - extracellular
- Viruses - intracellular
- Parasites - both
How is extracellular bacteria killed?
Extracellular bacteria is tagged by antibodies and killed inside of neutrophils. The liver has Kuppfer cells that also ingest and kill bacteria.
How is intracellular bacteria killed?
TH1 T cells recognize the bacteria and secrete interferon-gamma, which initiates the host macrophage to kill the intracellular bacteria
How are yeast and fungi killed?
Antibody tags the yeast, and it is eliminated via blood neutrophils. Or tagged with antibody and ingested by liver Kuppfer cells.
The antibody opsonizes the yeast and it it ultimately killed by neutrophils.
What cells recognize viruses and cause virally infected cells to die?
CD8 cytotoxic T cells
**viruses are intracellular
Do antibodies reduce viral infectivity?
Not always - they may
**similarly, antibodies alone are unable to eliminate bacteria or yeast
What is unique about the Plasmodium falciparium parasite?
It lies dormant in RBCs and effectively “hides” in patients with malaria
What is one means of eliminating large parasites like Onchocerca volvulus?
IgE antibodies coat the parasite and eosinophils attach and attempt to eliminate them.
What cell type controls viruses in innate immunity? What cell type controls viruses in adaptive immunity?
NK cell; CD8 cytotoxic T cell
How long does adaptive immunity usu take to develop?
5+ days
What cell types are involved in adaptive immunity?
T and B lymphocytes with specific antigen receptors
**the receptors are not directly genome encoded, they are individualized
What kind of memory does adaptive immunity generate? How long does adaptive immunity last?
generates antigen-specific memory; lasts the lifetime of the immune person
Which eliminates infections faster - adaptive or innate immunity?
adaptive
Where do T lymphocytes differentiate? What do they do?
Differentiate in the thymus; they are effectors of cell-mediated immunity
Where do B lymphocytes differentiate? What do they do?
Differentiate in the bone marrow; secrete Ab proteins after they encounter an antigen
What is this: a foreign structure recognized by T cells, B cells, and antibodies.
antigen
What is this: the structure within antigens that binds to B and T cell receptors for antigens
epitope
This is an infection caused by staphylococci and streptococci which colonize skin damaged by a previous lesion (erosion due to scratching, atopic dermatitis, irritation due to a cold). The risk factors are humid, warm climates and poor hygiene. It typically appears as a group of vesicles that may burst and spread fluid produced by bacterial metabolism, which will then form a scab.
Impetigo
Which class of MHC molecules do CD4 T helpers use?
MCH II
Which class of MHC molecules do CD8 T killers use?
MCH I
What is this: ANY foreign substance that can bind to the Ig B cell receptor for antigen and can also bind to antibodies.
B cell antigen
What does it mean that T cell receptors have “dual” recognition?
The T cell receptor binds and recognizes both the peptide that is foreign and the MHC molecule to which it is bound.
How many chains do T-cell receptors have? What are the two combinations?
2 chains; alpha-beta or delta-gamma
This is found on ALL T cells and is a signaling molecule
CD3
This is a co-receptor that binds to MHC class I
CD8
Are free foreign peptides recognized by T cell receptors? What must they bind to so that they may be recognized?
No! Peptides must be bound to an MHC protein
This is a co-receptor that binds to MHC class II
CD4
What must happen to a T lymphocyte before it can provide the help required for a T and B cell response?
T lymphocytes must be bound by antigen that matches their receptor type, and they must PROLIFERATE and secrete cytokines
Why do you need T cells to proliferate in order to overcome a pathogen?
When the T cells proliferate, there are more cells capable of producing cytokines, like IL2 which is a growth factor for all lymphocytes. This allows the T cell army to grow and conquer the pathogen.
What happens when an antigen binds to its specific immunoglobulin receptor on a B cell?
The ag-specific B cell, which was simply resting, will divide, produce IL-2, continue to proliferate, and some activated B cells will mature into Ab secreting plasma cells, while others will become memory B cells
When a B cell comes in contact with an antigen, what two cell types can it differentiate into?
plasma cell which secretes Ab specific to the Ig receptor
memory B cell
What is the structure of the immunoglobulin monomer?
contains 2 light chains and 2 heavy chains which are identical and are bound by disulfide bonds; the ends of the light and heavy chains are the antigen-binding sites; contains a hinge region and an FC region which allows binding to cellular receptors
Which chain, light or heavy, determines the isotype or class of immunoglobulin?
heavy chain
What are the two components of the immunoglobulin?
F(ab) *antigen binding region
F(c) *crystalizable
How does proteolytic cleavage of the Ig differ with papain vs pepsin?
papain cleaves and creates 2 separate F(ab) components, while pepsin cleaves and leaves the 2 F(ab) components linked like a dimer
What are some ways in which antigens for B cells are recognized as foreign proteins?
- conformational determinant: dependent on how the protein is folded and its covalent structure
- linear determinant: depends on the linear sequence of the peptide when it is unfolded
- neoantigenic determinant: only recognized when the antigen is modified via peptide bond cleavage, revealing new COOH and NH2 termini
What must specific T helper cells do before they can help B cells?
DIVIDE
**this is why it takes 5+ days to generate a response
What must specific B cells do before they can make Ab?
DIVIDE
**this is why it takes 5+ days to generate a response
How long do memory T and B cells to a specific antigen last?
a lifetime!
Which immunoglobulin type is made first after infection?
IgM, then IgG
*IgM is always made initially, ut then drops to 0, while IgG is made and persists.
Why is it important to get booster shots?
Booster shots increase the binding strength, or the affinity of Ab to antigen. Also, they increase the number of Ab.
