Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
130 Cards in this Set
- Front
- Back
|
What are some physical barriers to infection?
|
epithelium, fluid flow, normal flora
|
|
|
What are some phagocytic barriers to infection?
|
neutrophils and macrophages
|
|
|
During phagocytosis, a lysosome fuses with a ____ to form _____.
|
phagosome; phagolysosome
|
|
|
Pathogen Associated Molecular Patterns are recognized by ____ on phagocytes.
|
Pattern Recognition Receptors
|
|
|
What is the MB-lectin pathway?
|
It's one of the three complement pathways. It reacts to mannose on pathogen surfaces.
|
|
|
How does the secondary response of adaptive immunity differ from the primary response?
|
It is much quicker and much greater in magnitude.
|
|
|
What is an antigen?
|
Any molecule that can bind to antibodies or T cell receptors.
|
|
|
Of the four classes of organic molecules, which are the most antigenic?
|
Proteins by far. Followed by carbohydrates. Nucleic acids and lipids are poor antigens.
|
|
|
What are some properties of a good antigen?
|
large molecule, structural complexity, neutral
|
|
|
Multiple areas (thousands) on an antigen can bind to different antibodies. These areas are called ____.
|
epitopes (aka antigenic determinants)
|
|
|
What is the antigen on influenza?
|
hemagglutin
|
|
|
Vaccines will try to target the bioactive ___ of viruses.
|
epitopes
|
|
|
What are the four basic kinds of protein in serum? Where will you find antibodies?
|
albumin, and alpha, beta, and gamma globulins
Gamma globulins are antibodies. |
|
|
What connects the light and heavy chains and the heavy chains to one another?
|
interchain disulfide bonds
|
|
|
What gives an antibody its 3D structure?
|
Intrachain disulfide bonds.
|
|
|
Human antibody shows variability where?
|
The N terminus end of the heavy chains and light chains.
|
|
|
What are the two families of light chains?
|
Kappa and lamba (both can exist within each family)
|
|
|
Which Ig families are likely to exist as polymers? What glues together the monomers?
|
IgA (dimer) and IgM (pentamer)
J chain |
|
|
Which three classes of antibody exhibit hinge regions?
|
IgG, IgA and IgD
|
|
|
Are Ag/Ab rxns reversible? What kinds of bonds are made?
|
Yes. No covalent bonds (ionic, hydrogen, van der Waals, hydrophobic)
|
|
|
What are the antibody classes based on?
|
The similarities in the C region of the heavy chains.
|
|
|
What kind of Ab might be referred to as tetravalent?
|
The IgA dimer. It has four binding sites.
|
|
|
Where are the three places you might find Ab?
|
In serum.
On the surface of B cells in plasma membrane. Associated with Fc receptors on the surfaces of other cells. |
|
|
Which antibody is most common in epithelium?
|
IgE
|
|
|
In connective tissue, which is the most common Ab?
|
IgG
|
|
|
What is the most common Ab in bodily secretion?
|
IgA
|
|
|
What's the most common antibody in the fetus? Why?
|
IgG. It's the only one that can cross the placenta.
|
|
|
What is the predominant class of Ab in serum?
|
IgG
|
|
|
How do antibodies neutralize viruses?
|
Typically, they bind to the active epitome on the protein coat. The one that would usually bind to the cell.
|
|
|
How do toxins poison the cell?
|
They bind to the surface and are taken into cells. Then, the toxic portion gets into the cytoplasm.
|
|
|
How do we vaccinate against toxins?
|
We make inactive "toxoids" that allow antibody generation.
|
|
|
How do Abs prevent bacterial adhesion?
|
They binds to and block the adhesive tips of the pili.
|
|
|
What types of cells biosynthesize IgA dimers?
|
B cells or plasma cells
|
|
|
Where will you find IgA-secreting cells?
|
Lamina propria.
|
|
|
What is a poly-Ig receptor?
|
It is on the adluminal aspect of the epithelial cells. By interacting with the J chain of an IgA dimer, it helps transport the dimer across the epithelium and into the lumen.
|
|
|
What part of the poly-Ig remains attached to the IgA in the lumen?
|
the secretory component
|
|
|
Why do plasma cells of the lamina propria secrete IgA, as opposed to other Ig types?
|
Something to do with the types of T cells found there.
|
|
|
What is main Ab found in gingival crevicular fluid?
|
IgG (derived from serum)
|
|
|
What is the main Ab that interacts with cariogenic pathogens?
|
IgA
|
|
|
What families of Ab have Fc receptors?
|
IgG, IgA, and Ig E
|
|
|
What is opsonization?
|
Coating by anything that tags the extracellular pathogen for phagocytosis.
|
|
|
Opsonization is a classic example of the interaction between ___ and ___.
|
innate; acquired immunity
|
|
|
What are PRR and PAMP?
|
PRR: pattern recognition receptor
PAMP: pathogen-associated molecular pattern |
|
|
What are some PAMPs?
|
dsRNA, mannose, LPS
|
|
|
What is ADCC?
|
Antibody dependent cell-mediated cytotoxicity. IgG bound to pathogen binds to Fc receptors on NK cells, triggering them to release granules that kill the pathogens.
|
|
|
What two kinds of cells are involved in ADCC?
|
Eosinophils with FcE receptors and NK cells with FcG receptors.
|
|
|
Does ADCC kill intracellular or extracellular pathogens?
|
Both.
|
|
|
What kind of receptors are on mast cell surfaces?
|
FcE
|
|
|
What do eosinophils do? How?
|
They are associated with killing parasites. They have FcE receptors. IgE coats the parasites and eosinophils release their granules.
|
|
|
What is the importance of IL-5 in the elimination of worms?
|
Mast cells make IL-5. IL-5 causes production of eosinophils. Eosinophils kill the worms through ADCC
|
|
|
Which complement pathways are innate? Acquired?
|
Acquired: classical
Innate: MB-lectin and alternative |
|
|
Which Ab can activate the classical complement pathway?
|
IgG or IgM pentamers
|
|
|
Where are complement proteins found?
|
C1 through C9 are all found in serum, but in their inactive forms. (They are activated by proteolysis.)
|
|
|
The classical complement pathway is activated by the binding of either two ___ molecules or an ___ pentamer to the pathogen.
|
IgG; IgM
|
|
|
The Ab/Ag complex interacts with C1, which then cleaves and activates ___.
|
C4
|
|
|
C1 has __ globular domains, at least __ of which must be activated to activate the cascade.
|
6; 2
|
|
|
Only the classical pathway activates __, __, and ___.
|
C1; C4; C2
|
|
|
The complement proteins __, and ___ can act as opsonins.
|
C3b; C5a
|
|
|
Some complement proteins enhance vascular permeability, allowing __ and __ to reach the site of infection.
|
Ab; macrophages
|
|
|
Which complement proteins enhance vascular permeability?
|
C3a, C4a, and C5a
|
|
|
The terminal complement proteins (C5, C6, C7, C8, and C9) polymerize to form the ____.
|
membrane attack complex
|
|
|
What are the three things that complement can do?
|
1. opsonize
2. activate inflammation 3. form membrane attack complex |
|
|
What are primary lymphoid tissues?
|
bone marrow and the thymus
|
|
|
_____ cells give rise to B cells, T cells, and NK cells, while ____ cells give rise to all other formed elements of blood.
|
Lymphoid progenitor; myeloid progenitor
|
|
|
What are CD molecules?
|
"Clusters of Differentiation"
They are cell surface molecules that are found on immune cells. You can identify the cells by their CDs. |
|
|
(Re: CDs) All T cells express ___, but will have only one of the following: ___ or ___.
|
CD3; CD4; CD8
|
|
|
Which CD do B cells express?
|
CD19
|
|
|
B cell activation is a two step process. What are the steps?
|
1. Antigen binds to B cell antigen receptor.
2. B cell comes in contact with a T cell, which releases a cytokine that induces differentiation. |
|
|
When B cells leave the marrow, what kinds of Ab are the showing on their surfaces?
|
IgM and IgD
|
|
|
What is class switching?
|
When the B cell stops secreted IgM and switches to IgE, IgA, or IgG or becomes a B memory cell.
|
|
|
How does the memory B cell differ from the original B cell?
|
It's threshold for activation is lower.
|
|
|
In the absence of T cell cytokines, the activated B cell will differentiate into what?
|
An IgM secreting plasma cell.
|
|
|
What is a T dependent antigen?
|
Requires the communication of T and B cells to be neutralized.
|
|
|
What kinds of molecules are T dependent? T independent?
|
T dependent: proteins
T independent: carbs, FAs, and NAs |
|
|
What kind of antibodies are produced during T independent activation?
|
IgM
|
|
|
Is graft rejection a response from the innate or acquired system?
|
acquired
|
|
|
Is graft rejection mediated by T cells or B cells?
|
T cells
|
|
|
Describe the structure of MHC I and MHC II.
|
They are both heterodimeric glycoproteins. They are noncovalently associated.
Both have a groove that acts as a peptide binding site. |
|
|
MHC I is expressed on all ____ cells in the body.
|
nucleated
|
|
|
Which cells express MHC II?
|
B cells, macrophages, dendritic cells, and some activated T cells.
|
|
|
Which subunit of MHC I does not integrate into the cell membrane?
What are the other three parts? |
beta2-microglobulin
a1, a2 and a3 (a3 inserts into membrane) |
|
|
What are the four subunits of MHC II? Which ones insert into the cell membrane?
|
a1, a2, b1, b2
a2 and b2 insert into the cell membrane |
|
|
Which kind of MHC has b2-microglobulin? What's unique about its genetic origin?
|
MHC I. b2-microglobulin is encoded for on a different protein
|
|
|
Human MHC is highly ____, meaning many phenotypes are possible.
|
polymorphic
|
|
|
How is MHC inherited?
|
It is codominantly expressed. You get one set of genes from mom, one from dad. All combos are possible. Each cell has both kinds.
|
|
|
What are the B cell surface antigen receptors?
|
antibodies
|
|
|
What is positive and negative selection in the thymus?
|
Negative: cells that interact strongly with self-antigen are eliminated.
Positive: Cells that are capable of interacting with MHC. |
|
|
About what percentage of double positive cells are eliminated? Why?
|
About 95% of double positive cells die because they are potentially auto-reactive.
|
|
|
Like B cells, T cells are ____, meaning they only express one kind of antigen receptor.
|
monospecific
|
|
|
What is a naive B or T cell?
|
A B or T cell that has not yet encountered its antigen.
|
|
|
CD8 T cells generally become ___. CD4 T cells generally become ___.
|
cytotoxic T cells; helper T cells
|
|
|
What are the two T helper subsets we will look at?
|
TH1 and TH2
|
|
|
For a CTL to kill a cell, what two things must be present on the cell surface?
|
The foreign antigen and the self MHC.
|
|
|
CD4 T cells only recognize foreign antigens on an antigen-presenting cell under what circumstances?
|
The antigen must be bound to MHC II.
|
|
|
CD8 T cells only recognize foreign antigen when it is bound to what?
|
MHC I
|
|
|
What kinds of antigens do T cells react against?
|
proteins
|
|
|
How does the professional antigen presenting cell get the antigen and present the antigen?
|
It digests the antigen intracellularly, associates them with MHC and re-expresses them on the cell surface.
|
|
|
What are "professional" antigen presenting cells?
|
Those with MHC II, e.g. macrophages, dendritic cells, B cells, some T cells
|
|
|
How do professional antigen presenters get the antigen in the cell?
|
endocytosis
|
|
|
How does the antigen get into non-professional antigen presenters?
|
They are within the cell, like viruses.
|
|
|
Peptides are required for MHC presentation. So, how do perfectly healthy cells get MHC on their surfaces?
|
They put self peptides in the MHC, so, theoretically, the T cells should not recognize it.
|
|
|
The structure of the T cell antigen receptor is kind of like the MHC II structure. How?
|
Both have an alpha and beta chain, each of which has a transmembrane region.
|
|
|
What is alloimmunity?
|
When an individual gains immunity to a part of another member of the same species, as with an organ transplant.
|
|
|
T cell activation involves what two steps?
|
1. The T-cell receptor interacts with the peptide/MHC combo.
2. Secondary signals from the antigen-presenting cells. |
|
|
What is alloimmunity?
|
When an individual gains immunity to a part of another member of the same species, as with an organ transplant.
|
|
|
T cell activation involves what two steps?
|
1. The T-cell receptor interacts with the peptide/MHC combo.
2. Secondary signals from the antigen-presenting cells. |
|
|
Which receptors recognize conformation dependent epitopes?
|
Only antibodies can. The T cell receptors only recognize short (perhaps linear) peptides.
|
|
|
Is B and T cell specificity determined before or after they encounter antigen?
|
before
|
|
|
When T cells are activated, they start showing a receptor for which cytokine? Which cell produces this cytokine?
|
IL2
T helpers themselves often secrete IL2, so T helper activation is often (but not always) required for T cytolytic activation. |
|
|
Do activated CD8 T cells require secondary signals to work?
|
No. They're active. They just need to recognize the peptide on MHC I
|
|
|
What are the two major kinds of CTL effector molecules we discussed?
|
perforins and granzymes. The perforins let the granzymes in. The granzymes activate caspases and the cell undergoes apoptosis.
|
|
|
How does the acquired system cause osmotic lysis?
|
If IgM or IgG binds to an antigen, it can activate the classical complement pathway, which will form the membrane attack complex.
|
|
|
How do CTLs help prevent tumors?
|
Tumor cells display abnormal peptides (pieces of oncogenes) on their MHC I.
|
|
|
How are subsets of T cells differentiated?
|
By the kind of cytokines they secrete.
|
|
|
What do TH1 cells do?
|
Activate macrophages (this is the most important thing); induce B cells to produce opsonizing antibody (typically IgG).
|
|
|
What do TH2 cells do?
|
Predominantly, they activate B cells.
They also have some effects on macrophages. |
|
|
What is the classic TH1 cytokine?
|
gamma interferon (IFN-gamma)
|
|
|
What are the two TH2 cytokines I want to remember?
|
IL-4, IL-5 (involved in parasite infection)
|
|
|
Which kinds of T cells activate macrophage?
|
TH1
(TH2 may actually suppress macrophages) |
|
|
What kind of T cell induces formation of IgE?
|
TH2
|
|
|
What does gamma interferon do?
|
In activates macrophages and produces IgG that enhances opsonization.
|
|
|
Why are TH1 cells said to be involved in cell-mediated immunity?
|
They activate CELLS (macrophages and neutrophils) to induce killin
|
|
|
Tuberculosis bacteria like to live within ____. They prevent fusion with ___. However, TH1 cells may be able to overcome this effect.
|
phagosomes; lysosomes
|
|
|
If you have a positive TB test, you get an xray to check for ____, which are basically large clusters of ____ surrounded by ___.
|
granulomas; macrophages; TH1 cells
|
|
|
Quick immune reactions are mediated by ___ binding to ___ cells. Delayed hypersensitivity is mediated by cytokines released by___.
|
IgE; mast cells; TH1
|
|
|
How does the TB test work?
|
It's a delayed allergic response. The memory cell response causes a reaction.
|
|
|
Things to know about TH2
|
IL-4: activates mast cells (with IgE)
IL-5: activates eosinophils IL-10: suppresses macrophages |
|
|
Define:
Syngeneic Allogeneic Xenogeneic |
Syngeneic: genetically identical graft
Allogeneic: graft from same species Xenogeneic: graft from different species |
|
|
What is hyperacute rejection?
|
Very quick reaction against foreign (human) MHC. Indicates previous exposure to foreign MHC.
|
|
|
Which kinds of antibody DO NOT have Fc receptors?
|
IgM and IgD
|
