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immunology
n/a
56
Microbiology
Graduate
01/09/2013

Additional Microbiology Flashcards

 


 

Cards

Term
What is the function of lactoferrin as an antimicrobial?
Definition
This complexes with most available Fe; bacteria must uptake Fe to survive.
Term
What is the function of apolactoferrin as an antimicrobial?
Definition
Complexes with receptors on certain cells that bacteria use to enter these cells.
Term
What opsonizers can activate the complement pathway?
Definition
C-reactive protein, serum amyloid protein, mannose binding lectin, C3, antibodies
Term
Which cells secrete the plasma proteins (such as C reactive protein) that opsonize bacteria?
Definition
hepatocytes. These are secreted continuously, but CRP and SAP are rapidly upscaled in the case of infection.
Term
What are the three pathways for C3 activation?
Definition
classical: antibody binds to pathogen, attracts C1 (a protease) which bind+ cleaves C2 + C4, which together cleave C3
alternate: C3 binds pathogen itself, cleaving spontaneously
lectin pathway: mannose-binding lectin (a serine protease) binds to pathogen, recruits and cleaves C2/C4
Term
What is the positive feedback loop in C3->C3b conversion?
Definition
C3b is a component in an alternate form of C3 convertase (C3b+Bb)
Term
What are the components of C5 convertase?
Definition
C3b + C3 convertase (either C3/Bb or C2/C4 form)
Term
What is the effect of C5a/b?
Definition
C5a is a chemoattractant for phagocytes.
C5b attracts other complements to form a lysing device (membrane attack complex).
Term
Which complement turns on the adaptive immune system?
Definition
C3d
Term
What are the primary activites of NK cells in response to viral attack?
Definition
1. use granules to promote apoptosis of infected cells
2. release INF-gamma to recruit macrophages
Term
What part of the immune system does INF-a,b turn on?
Definition
Systemic effects - all cells that encounter enter anti-viral state (increased proteolysis, viral mRNA degradation) Also, NK's are turned on.
Term
What larger class of receptors is a toll-like receptor a member of?
Definition
PAMP (pathogen associated molecular pattern) receptors
Term
Which cytokines are fantastic at activating macrophages? Who secretes them?
Definition
IFN-y ("gamma"), secreted by NK cells (among others)
Term
What are the effects of mast cell granules?
Definition
Redness (increased capillary engorement)
swelling ("", + increased leakiness due to tight junction breakdown)
Pain - stimulation of nociceptors
Both effects mediated by serotonin and histamine
Term
What are the effects of mast cell granules?
Definition

Histamine, serotin, heparine: pain, redness, swelling (neutrophil chemokine), clot-freeness (short-term)

prostaglandins, leukotrienes

Neutral proteases: cleaves C3->3a, tissue damage to promote clots and scars

Prostaglandins and leukotrienes -> swelling and bronchospasm

IL-4 and TNF -> attract neutrophils and eosinophils, systemic inflammation

 

Term
what are the primary cytokines that mast cells secrete?
Definition
IL-4 (attracts especially eosinophils), TNF-a
Term
What are the 4 functions of macrophages?
Definition
1. phagocytose
2. Antigen presentation
3. cytokine secretion (can modify adaptive immune system, recruit NK's, cause inflammation among others)
4. healing - by stimulating angiogenesis + fibrosis
Term
What are the affects of TNF?
Definition
activate neutrophils and endothelial cells (inflammation, stickiness), cause hypothalamic fever, cause hepatic acute phase protein production, cause muscle/fat catabolism, enhance apoptosis.
Term
What is in neutrophil specific and azurophilic granules?
Definition
azurophilic - myeloperoxidase (makes bleach)
specific - lactoferrin, lysozyme
Term
How do antibodies activate mast cells/eosinophils?
Definition
IgE is already on the mast cell/eosionphil membrane - binding of antigen activates the cell.
Term
What are the actions of major basic protein?
Who secrets it?
Definition
1 a) mast cell degranulation
b) proteolysis of sulfated proteoglycans (heparin, parasites)
2 eosinophils
Term
What is the nature of eosinophil granules that makes them well-suited to fighting parasites?
Definition
they secrete several enzymes that break down tough outer coverings of parasites, including MBP, acid phosphatase, elastase
Term
Which T cells express CD4/CD8?
Definition
Helper T cells - CD4. Cytotoxic T cells - CD8
Term
Which cells express MHC II?
Definition
dendritic cells, macrophages, B cells (!)
Term
What type of cells perform cross presentation?
Definition
dendritic cells (this is when the peptides leak out of the phagosome to present to cytotoxic T cells via MHC I)
Term
What protein moves antigenic peptides from the cytosol to the ER?
Definition
TAP - transporter associated with antigen processing
Term
What sort of lymphocytes/lymphatic tissue are found in the skin?
Definition
scattered memory B's and T's, gamma-delta T's
Term
What is the name of the epitope-specific portions of variable regions in antibodies?
Definition
CDR's - complementary determining regions
Term
Which Ig's are most long-lived? Why?
Which Ig's are most prevalent? Where?
Definition
IgG is long lived because when it is endocytosed, the FcRn receptor makes it be recycled instead of lysosome-degraded.
IgA is the most plentiful, found especially in secretions.
Term
What enzyme creates junctional diversity in antibodies and TCR's?
Definition
TdT - terminal deoxynucleotide transferase
Term
Which are equivalent between heavy and light antibody chains and a and b TCR chains?
Definition
heavy -> b
light -> a
Term
a cell express only the heavy chain of an immunoglobin. What type of cell is it?
Definition
A pre-b cell
Term
A cell expresses only IgM. What type of cell is it
Definition
an immature b-cell
Term
Which type(s) of B cell can be found in the spleen that is NOT yet mature?
Definition
immature B cells
Term
What stage of T cell is double-positive for CD4/8?
Definition
immature T cells - pro and pre are in analgous receptor making modes to pro and pre B cells
Term
What sort of cell presents antigens to thymocytes during their education?
Definition
epithelioreticular (thymic reticular) cells
Term
What is the signal and receptor (give CD #) that causes T cell proliferation?
Definition
Signal is IL-2; receptor is IL-2 a,b,y subunits. a-subunit is CD 25
Term
When APC's bind to T cells in a synapse, what is the primary means of causing differentiation of the T cell?
Definition
cytokines (not membrane-bound receptors/ligands)
Term
what is the effect of INF-a?
Definition
this is a type I interferon (like INF-B), so it turns cells into the "antiviral" state
Term
What do HLA genes encode?
Definition
MHC molecules
Term
what is invarient chain? What are steps of its removal?
Definition
it's a protein that binds MHC II to stabilize it/ prevent it from binding ER proteins. Degraded into CLIP, then removed by HLA-DP
Term
What do all T cells display (CD)?
Definition
CD3
Term
What is NF-kB?
Definition
a pro-inflammatory transcription factor
Term
What determines what sort of Th into which the mature-naive T cell will differentiate?
Definition
cytokines from APC - reflects which PAMP (TLR) receptors were activated and what the cytokine milieu around the infection was and what the genetics of the host are.
Term
Why do activated Th cells still need TCRs?
Definition
They should only secrete cytokines at the point of infection
Term
What is the overall function of a Th2 cell?
Definition
1) stimulate eosinophil/mast cell inflammation
2) stop classic macrophage-driven inflammation
3) promote Th2 formation and diminish Th1 formation
Term
What are the different effects of Th2 vs. Th1 cells on innate immunity and B cells?
Definition
Th2 - M2 (repair/fibrotic) macrophages, eosinophils/mast cells active, neutralizing IgG
Th1 - M1 macrophages, neutrophils, opsonizing IgG
Term
What do Th17 cells secrete?
Definition
IL-17, which attracts neutrophils in the skin, mucosal areas.
Term
Name some anti-inflammatory cytokines
Definition
IL-10, TGF-B
Term
What is Fas and what binds it?
Definition
This is a death receptor on stressed cells; Fas ligand binds this (on cytotoxic T cell)
Term
What are granzymes?
Perforins?
Definition
Perforins puts holes in cell endosome that has endocytosed T cell granule contents
granzymes activate caspases (start apoptotic mechanism)
Term
How do CTL's help macrophages kill cells?
Definition
They secrete INF-y, which makes Mq's more active, so they eat more infected cells!
Term
Are effector T cells short- or long-lived?
Definition
short - they have Fas and other receptors that shut them down pretty soon after they're activated
Term
Why do NK cells kill cells which have MHC-suppressing viruses?
Definition
The NK cells need a continuous negative signal (activates phosphatases which act on ITAM regions of activating receptors) to keep from killing. This negative signal is MHC+self peptide
Term
What's the signal for B-cell inactivation?
Definition
a B-cell has its membrane-bound Ab bound by antigen, and has its FcyR bound by antigen-bound Ab. A "small immune complex"
Term
What is the poly-Ig receptor?
Definition
Binds to J-chain of IgA/M Ab to transcytose it to gut lumen
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