Immunology Flashcards
T/ B cell involved in innate immunity
IgM antibody production by CD 5+ subset of B cells
Main signalling molecules in bacterial damage and phagocytes recruitment
Cytokines
TNF - alpha
IL-1
Chemokines/ IL-8
3 complement pathways
Classic
Alternate
Mannose binding lectin
3 main purposes of complement
- label micro-organisms ( i.e. opsonisation)
- recruit phagocytes (i.e. chemotaxis)
- destroy- microorganisms by perforating the cell membrane (i.e. cytolysis)
How many main protein in complement cascade
9 complement proteins
Protein of MAC
C5-8 which then activate lots of C9s in a ring to form the MAC
Inflammatory complement mediators
C3a - the best,
C5a - pretty good,
C4 - pretty useless
Trigger(s) for classic complement pathway
IgG antibody (bound to something)
- therefore needs the adaptive immune system to have already worked
Other triggers
* Aggregated immunoglobulin
- Some RNA viruses
- Staphlococcal protein A
- Polyanions and cations e.g. heparin
- C-reactive protein
- Some proteolytic enzymes
Trigger(s) for alternate complement pathway
Main:
- C3 binding to bacteria
Other
* Aggregated immunoglobulins
* C3 nephritic factor (antibody to an enzyme activating C3)
- LPS (endotoxin)
- Some acute phase proteins i.e. mannose binding protein, C reactive protein
- Radiographic contrast media
- Plant and bacterial polysaccharides
Is the membrane attack complex (MAC) better in gram neg or pos bacteria
much more effective in gram negative
Mechanisms for protection of host cells against complement (MAC)
Membrane-bound complement inhibitors on cells include:
- DAF (decay accelerating factor) and MCP (membrane cofactor protein) which break down C3 convertase
- HRF (homologous restriction factor) C8 binding protein and CD59 which prevent the formation of MAC on host cells
DAF, MCP
Decay accelerating factor
Membrane cofactor protein
break down C3 convertase
HRF
homologous restriction factor
- C8 binding protein and CD59 which prevent the formation of MAC on host cells
Alternate name NK cells
large granular lymphocytes
NK cells and MHC class signalling
inhibited when they recognise their own MHC Class I molecules on target cells
kill target cells in which MHC Class I molecule expression has been down-regulated allowing escape from CTLs
also recognise other activating (and inhibiting) receptors on the surface of target cells
NK cells and antibodies
NK cells can acquire antibody (Fc portion of IgG) via CD16 Fc receptors allowing specific antigen recognition - ADCC
THings released by NK cells
perforins and granzymes to kill cells
Make interferon gamma
NK cells and MHC 2
no relation/ no interaction
Main cytokine that increases body’s temp/ set point
IL-1
Cytokines from macrophages that increase selectin and integrins activation on endothelial cells
TNF-alpha
Il-1
Cytokine that causes liver to release inflamamtory things
TNF-alpha
IL-1β and IFN-γ and IL-6 also very improtant
Cytokines released by DCs after activation by TLRs?
IFN-alpha/ beta
TNF-alpha
IL-6
IL-12
Increased surface expresison molecules in DC after activation
CD 80.86
MHC - II
CD 40
HLA molecules encoded by genes on which chromosome
6
MHC Class 1 regions (on chromosome)
A, B, C (technically also E)
MHC Class 2 regions (on chromosome)
DP, DQ, DR
Co-dominance in HLA
Cells will present proteins from all the genes it has available to it
is beta-2 micro globulin in MHC1 or MHC 2
MHC 1
Which cells present MHC 1
all nucleated cells
WHich cells present MHC 2
APCs
- macrophages
- DC
- B cells
what is CD3 related to
a TCR, doesn’t differntiate CT T cell vs TH cell
CD4 vs CD8 on which T cells
CD4 on TH,
CD8 on CT T cells
2 TH cells for every 1 cytotoxic T Cell
Break up of extra-cellular vs intra-cellular proteins by APCs
extra-cellular
- broken down by lyosoomes
- presented in MHC 2
intra-cellular
- broken down by proteosome
- presented on MHC 1
Cytokines produced by TH1, and basic role
IFN-gamma
TNF
Intra-cellular microbes
Cytokines produced by TH2, and basic role
IL-4
IL-5,
IL 13
Helminthic parasites
Cytokines produced by TH17, and basic role
IL-17
IL-22
Chemokines
extra-cellular bacteria, fungi
Immune reaction triggered by TH1
macrophages
IgG production
Immune reaction triggered by TH2
IgE production
mast cell/ eosinophil activation
Immune reaction triggered by TH17
recruit neuts, macrophages
How do cytotoxic T cells kill cells?
perforins - form a pore
granzymes - activate apoptotic enzymes
CD95 activation (FAS) by CD 95L - activates apoptotic enzymes
Main cytokine in T-cell activation/ maturation
IL-2
- produced by t-cells themselves (autocrine growth factor)
B1 subset of B cells
Naive B cell
- just produce IgM
- Do not produce memory cells
- Identified by the expression of the CD5 cell surface marker
B2 subset of B cells
- Respond to T-dependent antigens
- Undergo class switching so all isotypes of antibody can be produced
- Produce memory cells
- Do not express CD5
B Cell co-stim factor
CD 40 (on B cell) with CD 40L on activated T-helper
gene segments that combine to form antibody molecule
- heavy chain gene segments: V, D, J, C
- light chain gene segments: V, J, C
5 heavy chain C gene segment determine isotype:
μ,γ,α,δ,
2 light chain gene segments (κ,λ)
Can B cells produce more than one Ig subtype
B cell can simultaneously express both IgM and IgD on the surface
Otherwise No
IgG subclass that cannot cross placenta
IgG2
Relative quantities if Ig in serum
(IgA vs D vs E vs G vs M)
IgG>IgA >IgM >IgD >IgE
Complement binding efficiency if Ig
IgM, IgG3 >IgG1>IgG2
gene segments that combine to form TCR
V, J and C region (a chain)
and
V,D, J and C (b chain)
gene segments randomly selected, spliced, transcribed and translated into protein
What happens if a T lymphocyte encountering its specific antigen in the absence of a costimulatory signal via CD28
becomes anergic (unresponsive to appropriate stimulation)
Main Ig secreted into breast milk?
IgA
T helper cells involved in MS
TH 1
(Interferon gamma etc)
Can B cells produce kappa and lambda light chains in the same cell
no
Can B cells produces antibodies of more than one class
yes IgG and IgD
Cytokines are upregulatory except?
IL-10, TGF-β
Basic cytokine groups
- Interleukins
- Interferons - alpha (IFN-α), beta, gamma
- Tumour necrosis factor - alpha (TNF-α; cachetin), beta (lymphotoxin)
- Colony stimulating factors (CSF)
- G-CSF (granulocyte)
- M-CSF (macrophage)
- GM-CSF(granulocyte/macrophage)
- Transforming growth factor alpha - (TGF-α) beta (TGF-β)
Cell markers on immature thymic cells
- Tdt
- double positive CD4+/CD8+ (α/β)
- double negative CD3+ (γ/δ)
Cell markers on mature T cells
- TCR, CD3, CD2 (binds sheep RBC)
- CD4 (T h -interacts MHC Class II)
- CD8 (T c - interacts MHC Class I)
Cell markers on B cells
- CD19, CD20
- MHC Class II
- sIgM (sIgG on memory B cells)
- Complement receptors:
CRI, (CD35), CR2 (CD21- EBV entry)
Examples of live vaccines
- bacterial: BCG vaccine
- viral: Sabin (polio), measles, mumps, some CoVID
