Immuno CCOM 1 Flashcards
What do cells of the innate response recognize during an immune response?
structural motifs common to many pathogens: PAMPs
Pattern Recognition Receptors are responsible for this:
Toll receptors - CD14 binds w LPS and complexes with TLR4
What condition might exhibit an elevated CD14 level?
kawasaki disease
What are Nod-like receptors used for?
they can form inflammasomes that result in the initiation of cell death and cytokine release
CYTOSOLIC
What are some example of PAMPs?
LPS
mannose residues
f-met-leu-phe
bacterial peptidoglycan
What does Mannose binding lectin bind to specifically on bacteria?
repetitive oligosacchardies
What do scavengar receptors recognize?
anionic polymers
acetylated low density lipoproteins
old and dying host cells
ex: PSR for phosphatidyl serine during apoptosis
What are some factors in the innate immunity?
Type 1 interferons-cytokines phagocytes complement proteins NK cells gamma-delta T lymphocytes pyrogens (exo/endogenous)
What other cell may have similar function to NK cells?
gamma-delta T lymphocytes
What are exogenous and endogenous pyrogens?
exo: products of microorganisms that induce or act directly on hypothalamus
endo: IL1, IL6, TNFa - cause release of arachidonic acid that metabolizes to PGE2 which acts on hypothalamus
Describe active and passive immunity vs natural and acquired
active natural: pt acquires disease and recovers
active acquired: pt vaccinated
passive natural: mother passes immunity
passive acquired: pt given preformed IGs
Where do all leukocytes originiate from?
bone marrow
Where do lymphocytes first encounter pathogens?
secondary lymphoid tissues
Which cell type does the spleen have the most?
B lymphocytes
What is the more accurate view of the function of lymph nodes?
trap foreign molecules
concentrate these molecules in same location as appropriate WBC to increase opportunity
How do lymph node cells constantly recirculate?
about 2% of the lymphocyte pool recirculates every hour
to feel out the environment
-surveillance and communication
-80% lymphocytes end up in diff node by end of day
What are properiteis of MALT?
non-encapsulated
MALT cells recirculate to only other mucosal tissues
describe the markers for T cells
All are CD3
some are CD4 (helper)
somer are CD8 (ctotoxic)
What types of cells do hematopoeitec stem cells give rise to?
RBCs
WBCs
platelets
What are cytokine made of?
protein or glycoprotein
they act locally
What are the only cells that produce antibodies?
B cells
What is biological activity of Abs?
phagocytose
help lyse organisms
clump organisms together
What are some reducing agents of Abs?
mercapto: breaks apart 4 chains at disulfide bonds
Papain: breaks hinge to yield 3 fragments
Pepsin: yields 2 F(ab)2 (divalent)
After papin digests Abs, describe the properties of the fragments
Fab can still bind Ag Fc cannot bind Ag but is: crystallizable complementable C1q phagocytes placenta mediator
What is the order of concentraion of Igs in descending order?
GAMDE
What determines the type of heavy chain? What does the heavy chain define?
a.a sequence
heavychain defines isotype of Ig
What is the hypervariable region
Where there is contact with the epitope of the antigen. The regions that contact epitope is the idiotype
How many constant domains are on the light chain and heavy chain?
light: 1
heavy: 3
Which is the only Ab to cross the placenta?
IgG
What are the fucntions of IgG?
neutralizes toxins…
opsonizes antigens/bacteria
complement activation
IgM
secreted as pentamer Ag receptor as a monomer J chain joins units together no hinge region extra constant domian in heavy agglutinizes complements strong
What is the first Ab type formed in the primary immune reponse?
IgM
IgA
a dimer linked by J chain
has a secretory component in secretions-protects from protease
protects on mucosal surfaces
What is the predominant Ab found in bodily secretions?
IgA
Which Ab is passed along through breast milk?
IgA
IgE
simliar to IgM structure
allergic reactions (T1 hypersens)
releases histamines
parasitic infections
IgD
similar in structure to IgG
not sure of function really
might serve as marker of B cell differentiation
How can Igs be antigens?
because they are glycoproteins
ex: human Ig in mouse Igs.
ex: autoimmune
Do plasma cells produce IgD?
No
Half life of Igs?
G: 23 days A: 5.5 M: 5 D: 2.8 E: 2
Where is the site of hematopoeisis throughout life?
until 6 mo gest: yolk sac and liver
after: marrow
What is the cell marker for a hematopietic stem cell?
CD34
What is the order of B cell development?
HSC Cd34 pro B cell pre B cell immature B cell mature B cell
Which cytokines interact w pro B cells to continue differentiation?
IL 7
IL 3
(also stromal cells)
What happens when IL 7 and IL 3 interact w pro B cell?
Ig genes for variable heavy chain rearranges
Define the Pre B cell
expression of ruly rearranged Ig heavy chain and initiation of light chain rearrangement
Describe the first checkpoint in B cell dev
surrogate light chain interacts w rearranged heavy chain. It goes to cell surface. If they dont interact-> death
if they do-> live/allelic exclusion
What is allelic exclusion?
even though B cell encodes for 2 heavy chains and 2 light chains, only one of the loci will be expressed
Define the immature B cell
expression of surface IgM (sIgM)
What happens if the sIgM interacts w a soluble antigen? an insoluble antigen?
soluble: clonal anergy
insoluble: deletion/apoptosis
Define the mature B cell
expression of both sIgM and sIgD
Describe the specificities of sIgM and sIgD on the developing b cell
they have the same specificity
different isotype but same idiotype?
Which transmembrane proteins does Ig associate with in the developing B cell?
Ig-alpha
Ig-beta
(all form BCR)
What must occur for the B cell to develop beyond the matrue B cell?
crosslinking of BCRs through antigen epitopes in secondary lymphoid tissues
What is the Clonal Selection Theory?
differentiating stem cells rearrange their genes for the hypervariable region to produce clones of B cells that respod to a specific epitope. Produces plama cells or memory B cells
What is tolerance?
specific unresponsiveness
prevents reaction against self
checkpoint
What are T-independent Ags?
examples?
Can activate B cells without help from T cells LPS flagellin dextran polysaccharides any with multiple epitopes any that crosslinks sIg
What are Type 1 T-indep Ags?
What response do you see?
ex?
activate B cells without using BCr stim polyclonal activation heterophile Abs-many specificities B cell mitogens LPS Ebstein-Barr
What are Type 2 T-indep Ags? What response do you see? ex?
activate B cell by using BCR (sIg), and crosslinking sIg's capping- moves to one pole Monoclonal Activation B cells with only 1 specificity ex: carb, peptides, dextran
What class of Ab is synthesized in a Type 2 T-indep response?
only IgM
What happens if a Type 2 T-indep antigen becomes conjugated to a protein?
Switches to a T-dependent response
IgG2 is major Ab made
Describe the memory response for a T-indep antigen?
there is no memory response
identical to primary response
What are characteristice os T-dependent Ags
proteins, glycoproteins, or conjugated to proteins
Which age group responds poorly to T-indep Ags?
children under 2 years
Describe T-depedend responses
isotype switch occurs
but specificity stays same!
APC, T cell, B cell needed
Which cell surface ligand mediates the development from mature/naive cells to memory or plasma cells?
CD40 (on B cell)
CD40L (on T cell)
Why are memory cells faster to react to second exposure of antigens?
Isotype switch already ocured
At a higher activation state
more precursors
higher affinity Ag receptors
What is affinity maturation?
increased Ab binding strength somatic mutations in variable
‘survival of fittest’
BCRs on B cells are better too
(remember specificity does not change)
Describe the Lag phase of a primary resopnse
B cells undergo clonal selection
7-10 days
What is the first type of Ab produced in a primary response?
secondary repsonse?
primary: IgM
secondary: IgG is predominant
What is linked recognition?
eptiopes must be physically linked on same anithgen
What are examples of conjugated vaccines?
influenze type b
pneumococcal conjugate vaccine
What protects infants from disease?
maternal Ig
infant Ig after 6 mo
normal gut flora
What types ofinfections does breast feeding protect from
respiratory
GI
How many V, D, J and C chains in heavy and light chaings?
light: Vk=40 ; Jk=5 ; Vl=40 ; Jl=4
heavy: Vh=50 ; Dh=20 ; Jh=6 ; Ch=9
Desribe how you use a paired sera test
collect serum sample 1 durin illness
and sample 2 after recovery
If titer is 4X increase, then disease
ex: SARS
What is sensitivity?
a measure of ability to identigy diseased cases
Most helpful when negative-to rule out
there are false positives
good for screenings
What is specificity?
measure of ability to test non-diseased
Best when it is positive-to rule in
there are false negatives
good for confirmatory
What are the primary binding tests?
1) ELISA
2) IF
3) Blotting
4) Flow Cytometry
Describe ELISA
Add known antigens to well
Add diltued uknown serum
Add 2nd Ab conjugated w enzyme
Add chromagen for color
Descfribe Direct IF
Add tissue specimen to slide
Add Ab w conjugated flourescent
Look under UV scope to see it
Describe Indirect IF
When you dont have tissue, but you have serum (Abs)
Add 2nd Ab w Fluorescent
Immunoblotting
Separate Proteins
Transfer/Blot
Nitrocellulose
Detect bound Abs
Compare ELISA and blotting specificities and sensitivities
ELISA: high sense, low spec
Blot: low sense, high spec
What are ELISAs used?
pregnancy tests
viral hepatitis
RIST/RIA
When is IF used?
DFA: rabies, herpes
IFA: assay Abs
When is blotting used?
HIV, confirmatory
Alzheimer’s
FACS
measure number of cels w certain surface markers
CD4:CD8 ratios of HIV pts
tumor cells w markers
PBL populations
What is the CD4:CD8 ration in normal patients?
2:1
less in AIDS patients. Treatment returns to normal
What is the prozone effect?
insoluble precipitates:
antibody excess zone-none
equivalence zone- formed
antigen excess zone-none
Describe the Ouchterlony test
3 wells: 1) pt sample 2) known lab sample w tested Ag 3) Ab against Ag
3 interpretations: 1) complete identity-rainbow 2) Non-Identitiy- X 3) Partial Identity-spur
for fungal diseases
Which molecules are opsonins?
C3b
C4b
Which molecules are anaphylatoxnis? What do they do?
C5a > C3a > C4a
degranulation of mast cells and release of histamine/vasoactive
Which molecules are for margination? What do they do?
C5a
allows WBCs to adhere to vessels
Which is for chemotaxis?
C5a > C3a
What is the function of the membrane attack complex?
permeablizing membranes by adding pores to break it down via osmotic pressure
Which molecules regulate vascular tone?
C2a
C2 kinin
How are immune complexes removed in the complement cascade?
in plasma: via RBCs (via CR1)
in liver: phags
Describe the stains of basopphils, eosinophils, and neutrophils
basophil: dies w basic dyes
eosinophil: dyes w acid dyes
neutro: noes not stain w either
What are cells of the mononuclear phagocytic system?
monocytes, macrophages and their derivatives
What is the main signal to activate monocytes for phagocytosis?
IFN-gamma
What activates M1 macrophages?
what do they secrete?
classicaly acitaved
IFN-gamma, TLR ligands
secrete IL-1beta, IL-6, TNF
What activates M2 macrophages? What immune responses are they involved in?
alternatively activated
activated by IL-4, IL-13
parasitic immunity, allergies, wounds, tissue remodel
What are some positive chemotactic signals?
C5a Fibrinopeptide B Proinflamm. cytokines:IL1, TNF-a chemokines: IL-8 LTB4 (lipoxygenation/arach acid) LPS
What can cytotixic chemo drugs induce?
neutropenias
What are the 4 stages of phagosytosis?
- chemotaxis
- adherence
- Ingestion
- Digestion
name some adherence molecules for phagocytosis
opsonins:
C3b
Fc of Abs (IgG1, IgG3)
C-reactive protein
What are the 3 mechanisms for digestion in phagocytosis?
- Respiratory burst
- phagosome-lysosome fusion
- Toxic nitrogen oxides
Describe Respiratory burst
superoxide formed via NADPH oxidase
H2O2 formed via superoxide dismutase
OCl- formed via myeloperoxidase
Describe phagosome-lysosome fusion
lysosomes from granules
defensins and protegrins disrupt mmbrane
lactoferrin chelates iron
Describe toxic nitrogen oxides
the cNOS and iNOS pathways produce NO.
No inhibits iron enzymes and damages pathogen DNA.
(iNOS and resp burst form peroxynitrite)
What are the main cytokines that induce inflammation?
IL-1 IL6 IL-8 TNF-a IL-12
Which cytokines induce fever?
IL-1
IL-6
TNF-a
Which receptors/ligands are involved in rolling adhesion?
sialyl_Lewisx on the neutrophil:
E-selectins on endothelials
Which receptors/ligands are involved in tight binding?
integrins on neutrophil:
ICAM-1 on endothelials
Which receptors/ligands are involved in diapedesis?
integrins on neutrophil:
CD31 (PECAM)
Which complement pathway inhibitors can cause meningitis?
C5-8 deficiency
properdin deficiency
MBL deficiency
What cels are the major producers of IFN-gamma?
CD4 helper T cells
NK cells
What type of surface oplarity of bacteria enhance phagocytosis?
hydrophobic surfaces enhance phagocytosis
ex: M. tuberculosis
hydrophilic empede
ex: s. pneumoniae
What is the acute phase response?
a systemic resopnse to local inlammation fever increased hormone (ACTH) leukocytosis acute phase proteins
name some actue phase proteins
C3 CRP haptoglobin factor B \_\_\_\_\_\_\_\_ albumin/prealbumin fibrinogen
What can an elevated CRP level indicate?
unstable coronary artery disease
if in healthy: higher risk of CV disease
What is ESR?
erythrocyte sedimentation rate
Bigrinogen reduces charge on RBC so they clump.
ESR~ level of inflamm response
TB, tissue necrosis, rheumatic, MI, malignancy
What is the hallmark of local acute response?
influx of PMNs
What are the 3 enzyme cascades that are activated when endothelial cells are damaged?
complement system
blood clotting/kinin system
fibrinolytic system
What are matrix metalloproteinases?
degrade ECM proteins so free moveement of inflammatroy cells can occur
Describe the effedct of adenosine in inflammation
A1 receptor: enhances inflammation
-activated at low concentrations
A2 receptor: suppresses inflammation
-activated at high concentrations
What is the hallmark of chronic inflammation?
accumulation/activation of macrophages
-granulomas too
Descsribea granuloma
necrotic center
fibrosis/scar formation
enlargement and replacement of normal tissue
M1 center, M2 periph
Describe tetanus
incubation period?
causes what?
immune response?
2 weeks incubation
causes spastic paralysis
pharm active levels but too low for immune response
No natrual active immunity
