Term
| If someone has recurrent extracellular bacterial infections, what kind of deficiency would we assume? |
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Definition
| and antibody deficiency!! |
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Term
| How do we fight extracellular bacteria? |
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Definition
| innate immunity and antibody |
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Term
| How do we fight intracellular bacteria? |
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Definition
because antibody can't enter cells, need to fight another way.
cell-mediated immunity! aka humeral immunity |
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Term
Extracellular bacteria:
If you haven't seen a bug before, complement will bind. What type of complement activation do you get? |
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Definition
| alternate pathway... not as good as classical |
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Term
Extracellular bacteria:
If you have seen the bug before, antibodies will bind and fix complement. What pathway is activated by this fixing of complement? |
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Definition
| the classical pathway - this is a much more efficient way to produce the MAC attack |
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Term
Extracellular bacteria:
If you've seen the bug before, complement will bind and activate complement via what pathway? |
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Definition
the alternate pathway!
(remember that complement is also activated by the binding of antibody which fixes complement) |
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Term
| True or false: Regardless of whether you've seen the bug or not, phagocytosis will have the same level of efficiency. |
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Definition
FALSE! Phagocytosis is more efficient if you've seen the bug before.
However, the bug will be killed in the same way regardless of whether it's been seen before |
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Term
Explain post strep glomerulonephritis.
What happens as a result? |
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Definition
Immune complexes made up of antibody and antigens clog up the holes of the kidney.
This activates complement and frustrated phagocytosis by neutrophils. This lead to destruction of kidney tissue |
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Term
| Explain frustrated phagocytosis in the context of glomerulonephritis. |
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Definition
-Neutrophils recognize the Fc area of the antibodies in the complexes that are clumped in the kidney.
- they become activated and want to phagocytose the kidneys
- they become frustrated because the kidneys are too big, so they spread themselves out until it gives up
- then it takes up whatever it can, and lays out its toxin on the surface of it |
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Term
| Explain post strep rheumatic fever |
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Definition
-The strep A antigen looks very similar to the antigens of the heart
- So, IgG antibodies screw up and become self-reactive by binding to the heart valves and myocardium
- activate complement and opsonize for phagocytosis
- frustrated phagocytosis occurs
- damage to myocardium and heart valves |
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Term
| Explain the basics intracellular bacteria |
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Definition
- make a decision to hire out inside cells
- only cells that really want bacteria are macrophages |
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Term
| What is the "war of the worlds" in intracellular bacteria? |
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Definition
| intracellular bacteria are trying to avoid getting killed so they can reproduce but macrophages are trying to kill them |
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Term
| How many antibiotics does it take to treat tuberculosis? |
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Definition
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Term
| What is the MID of tuberculosis |
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Definition
MID = minimum infectious dose
the MID for TB is 3
means you only need 3 bacteria to get TB |
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Term
| The incidence of TB overlaps with __. |
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Definition
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Term
| Explain the pathogenesis of TB |
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Definition
- it lives inside the phagosome
- it prevents the phagosome-lysosome fusion
- it has a protective coat to resist killing
- it shuts down the IFN gamma signal from T cells |
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Term
| How does the immune system deal with TB? |
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Definition
- the macrophages kill 10-20% of the bugs so that antigen presentation can occur, but there is no effective antibody response
- instead, the immune system forms Type I granulomas (aka tubercles) |
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Term
| What are granulomas covered in? |
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Definition
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Term
| Explain Th1 Cell mediated immunity. |
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Definition
The effector CD4+ T cell has come out of the lymph node (Instead of going to the B cell area) and heads out to site of infection.
They leave circulation and come out in the tissues. We call them Th1 cells.
Th1 cells produce a lot of interferon gamma which activates macrophages. |
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Term
| Th1 cells are involved in _ _ _ and Th2 cells are involved in _ _ |
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Definition
| cell mediated immunity, allergic response |
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Term
| Macrophages that have been activated by INF-gamma released by Th1 cells produce .... |
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Definition
a number of cytokines!
most important = Tumour necrosis factor |
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Term
| What does TNF do (classically)? |
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Definition
tumour necrosis factor kills tumour cells by apoptosis... but does many other things as well
-it is pleiotropic! |
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Term
| What does TNF do in the context of cell mediated immunity? |
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Definition
| when released by macrophages, it recruits more macrophages |
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Term
| When IFN-gamma activates the macrophages that were brought in by TNF, these macrophages become _ macrophages. |
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Definition
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Term
| What is special about angry macrophages? |
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Definition
- they are more phagocytic
- better at killing |
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Term
| Explain the usefulness of the macrophage wall. |
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Definition
macrophages surround the infected macrophages and prevent anything from going in or out (want to starve out the TB)
Macrophages inside the wall will be producing toxic materials that are usually taken out, hoping that will limit TB's ability to survive |
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Term
| In order to maintain the macrophage wall, what must happen? |
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Definition
- continuous production of IFN-gamma by Th1 cells
- continuous production of TNF |
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Term
| What happens when you have HIV and TB? |
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Definition
| HIV kills CD4+ T cells (so no more Th1 cells) --> therefore, no IFN-gamma, no more macrophage activation, no more TNF, so no more macrophages coming in... no more macrophage wall siege |
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Term
| Why is it important to test for TB? |
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Definition
| some monoclonal antibodies directly bind TNF and clear it from circulation --> no more siege! latent TB becomes active |
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Term
(Intracellular bacteria)
Why is Listeria more common in Europe? |
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Definition
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Term
| Where do we get Listeria from in Canada? |
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Definition
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Term
| How does listeria escape killing? |
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Definition
- listeria gets inside the cell and lives in a vacuole
- it escapes the phagosome and live in the cytoplasm... so when the lysosome comes to merge, the bug is already gone |
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Term
| Protein antigens inside the cell (cytoplasm) are constantly being degraded and peptide is presented in the groove of _____. |
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Definition
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Term
| How does the immune system realize that listeria is around, (considering it escaped killing)? |
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Definition
| Since listeria is in the cytoplasm, they get presented with Protein antigens inside the cytoplasm that are degraded and presented in the context of class I MHC... |
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Term
| Peptides from the cytoplasm that are presented in the context of Class I MHC are recognized by ___. |
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Definition
| CD8+ T cells (cytotoxic T cells) |
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