Immunology Flashcards
Name 2/3 chemical/physical barriers
Lysozymes works as an antimicrobial agent
Defensins can kill bacteria or inhibit growth
Tight junctions can block the bacteria from entering
Name 3 outcomes of the complement system
Chemotaxis (recruitment of phagocytic cells)
Opsonization (phagocytes destroy the pathogen)
Lysis (formation of membrane attack complex which causes cell lysis)
What do phagocytes recognize?
PAMPS and ILCs
ILC-1 secretes….
IFNy which enhances macrophage function
ILC-3 secretes…
IL-17 and IL-22 to secrete chemokines and attract neutrophils
Name 4 phagocytes…
Macrophages, monocytes, neutrophils and dendritic cells
PAMPS/DAMPS =?
Pathogen associated molecular pattern/danger associated molecular pattern
PRRs function in…(3)
phagocytosis of microorganisms, cytokine production, and inducing co-stimulatory molecules in dendritic cells and macrophages
Name 4 ways of microorganism killing:
Degranulation of lysosomes, respiratory burts (ROS), NETosis (neutrophils), and nictric oxide pathway (macrophages, induced by IFNy, IL-1 or TNFa)
Why does the dendritic cells act as a bridge?
Once a dendritic cell recognizes a PAMP it will display the antigen and start T-cell activation
Name the 3 signals which are needed tor CD4+ T-cell activation
- MHCll/peptide binds to TCR
- Co-stimulation by CD80/86 binding to CD28
- Cytokine production by dendritic cells
Role of Th1…
Th1 stimulates macrophages as it secretes IFNy which enhances the nictric oxide pathway and allows CD40-CD40L binding (for B-cell activation!)
Role of Th17….
recruits neutrophils and IL-22 which induces anti-microbial peptides (only for extracellular bacteria!!)
Role of Tfh…
Helps the B-cell to produce IgG and allows opsonization of microbes
Name the 3 signals needed for B-cell activation
- whole antigen binding to BCR
- Co-stimulation by CD40-CD40L binding
- Secretion of cytokines (IL-21) and differentiation of the B-cell
- -> into plasma cell
What’s thymus indepent antigen?
Can activate B-cells without Tfh, but does not make memory cells and there is no isotype switching so only IgM can be made
Name 5 functions of antibodies
ADCC Opsonization to enhance phagocytosis Targeting complement pathway Aggregation to clump bacteria together Neutralization of bacterial toxins
Which type of IFN are produced by the presence of a virus?
IFN type 1, this produces IFNa and IFNb
How do NK cells recognize infected cells?
By absence of MHCl and the presence of PAMPS/DAMPS
How can a NK-cell kill?
Through TRIAL or via ADCC by IFNy and TNFa
Function of macrophages?
Macrophages can phagocytose and kill virus-infected cells, they secrete pro-inflammatory cytokines e.g. TNFa, nitric oxide and IFNa
Whats the difference between a naive and mature dendritic cell?
A naive dendritic cell can induce phagoycytosis but can not migrate
A mature dendritic cell can migrate and activate T-cell but can not induce phagocytosis
How is the antigen presented on MHCl? (nucleated cells)
The viral protein gets degraded by the proteasome and is transferred to the ER by TAP and is then loaded onto the surface by exocytosis
How is the antigen presented on MHCll (APCs)?
The viral protein gets phagocytoses and creates a phagosome, CLIP blocks MHCll and gets removed once HLA-DM opens MHCll up to enter the phagosome to get expressed on the surface through exocytosis
What is the function of cytotoxic T-cells?
They move to the site of infection and start killing the virus-infected cells
How do cytotoxic T-cells kill?
Through perforins and granzyme caspases which signal for apoptosis
Immunity =….
Recognition of non-self
Tolerance =…
Ignoring of self (tumors)
Central T-cell tolerance =…
It deletes T-cells with a high affinity to auto-antigens, this happens in the thymus
Peripheral T-cell tolerance…
Regulates mature T-cells to avoid self-reactivity by anergy and Tregs, happens outside the thymus
Where does T-cell development and activation take place?
In the bone marrow
How does selection work in T-cells?
+ selection: T-cell recognize MHC in the cortex and advance to the medulla
- selection: T-cells that recognize self-peptides in the medulla go through apoptosis, and the ones that don’t go into the circulation
How are auto-antigens presented?
with AIRE which can present all possible self-antigens for it to become expressed by mTEC
Whats the difference between natural and induced Treg?
Natural Treg are formed in the thymus and induced Treg are formed in the periphery from naive T-cells
Name 4 functions of Tregs (how can they block the immune system?)
By blocking IL-2 production by Foxp3 of CD4+ T-cells –> T/B-cell die without IL2!
Expression of CD25 to capture IL-2
Expression of CTLA4, as it binds to CD80/CD86 to give off inhibition signals
Production of TGFb and IL-10 to induce regulatory/anti-inflammatory cytokines
How does negative selection work in B-cell development?
If the B-cells bind to self-antigen they can either die or change their B-cell receptor and go through selection again (receptor editing)
What do transitional B-cells do?
They express IgM and IgD to enter the periphery
Auto-immunity=….
Loss of self-tolerance
Auto-immune disease =….
The damage as a result of auto-immunity
Systemic auto-immune disease =….
Auto-immunity on stuff that is present all over the body
Why are mutations in AIRE, CTLA4, FOXP3, C1q, IL10RA/RB related to auto-immunity?
Because they are all produced by Treg, because Treg works to dampen the T-cell activation so there is more chance of an auto-immune disease
Type 1 allergy mechanism…
IgE mediated, the allergen bind to IgE by recognition then the Fce receptor is bound to IgG and induces cross-linking which leads to mediator release e.g. hisamine
Type IV allergy mechanism…
The antigen binds to the T-cell which releases cytokines that activate the macrophages which release the mediator, this is Th1 mediated
Name 3 mediators
IL5+IL13 that amplify the Th2 response
IL6 + TNFa to promote inflammation and stimulate cytokine production
Histamine for extravastion, vasodilation and neuronal activation
Name the 3 phases of immune surveillance…
- elimination, tumor growth rises in the tissue
- Equilibrium, pre-state of cancer
- Escape, the tumor cells escape from the immune sustem due to poorly immunogenic variants and subversion of the immune system
Tumor antigen therapy =…
Injecting dead tumor cells and viable tumor cells to make antigen
How can a tumor evade the immune system?
Not having enough PAMP so it will be treated as a self-antigen
Low immunogenecity
Tumors may mutate so it will not be recognzied anymore by the antigen
Name 3 tumor-induced immune suppression…
TGFb and IL-10, they help induce Treg and attract it, so it will inhibit T-cells directly
Expression of PD-L1, this binds to the PD-L1 receptor on T-cells
Expression of IDO, which catabolizes tryptophan to kynurenine and inhibits the cell cycle arrest
Name 5 methods to fight tumors
Antibodies that recognize the tumor Adoptive T-cell therapy by using T-cells from the tumor Vaccines that provide immunogenecity Nanoparticles Checkpoint inhibitors
Passive vaccines….
Vaccines with the addition of antibodies, fast and perfect for immunodeficient patients, but expensive and no memory cells are made
Active vaccinations…
The antigen induces clonal expression of T/B-cells and form memory cells so that the next encounter is more rapid and effective
Natural live vaccines…
You use a virus from another organism to make a vaccine
Live attenuated vaccine….
You use a weakened pathogen that can not infect anymore, this can revert to its original type and become fatal
Inactivated vaccines…
The antigen is inactivated by heat or formaldehyde, less effective then live vaccines but safer
Vector vaccines…
You take a virus with a spike gene which can be active or inactive and you replicate it within the cells
Recombinant vaccines…
Protein needs to made in yeast cells, to take up DNA and isolate it to achieve the protein
Virus-like particles vaccine
You take an empty virus shell as a vaccine to mimic the structure of the virus, so not infectious as they lack genetic material
DNA/RNA viruses
In DNA you create pores in the membrane so that it can uptake DNA into the cell, for RNA you encase it in a lipid coat so that it can enter the cell te become replicated and make genetic material for it to cause an immune response
Toxoid vaccines…
The toxin is produced and inactived through heat or formaldehyde to start an immune response to get toxin-specific antibodies
Conjugate vaccines…
Combining T-independent sugar with a protein so it can present the protein part and still recognize the sugar part inside (the T-cell independent part)
Whats the disadvantage of mucosal administration?
The antigen can degrade and induce tolerance to the antigen
Why are adjuvants used?
To enhance the immune response, so you can use fewer does, get a faster immune response and to get long-lasting immunity
Name 5 immunostimulants…
Alum, binds to the antigen/PRR so that dendritic cells can mature and stimulate inflammation
Mineral oils that bind to TLRs
PAMPs
Depot formation, to cluster antigens and PAMPS together
Whats the difference between primary and secondary immunodeficiencies?
Primary are genetical and heritable, here you have intrinsic defects in the cells of the immune system
Secondary are acquired during life by e.g. malnutrition, trauma, HIV, chemo etc.
Whats the difference between specific and non-specific immunodeficiency?
Specific = T/B-cells Non-specific = Complement system and phagocytes
X-linked agammaglobulinemia (X-LA)…
there are no antibodies because the BCR doesnt function so they never leave the bone marrow, you can have T-cells but no memory cells can be made
Hyper-IgM, CD40-CD40L deficiency…
B-cells can only produce IgM because isotype switching can not take place –> no B-cell activation
SCID…
no thymus development so no invasion of the thymus by lymphoid cells because of a defective y-chain of IL-2 receptor or RAG1/2 deficiency
MHCll deficiency…
APCs do not have MHCll so there are no CD4+ T-cells present as there is no selection, so also no CD8+ T-cells, no Treg and only IgM can be made
Phagocytic deficiency…
Here you have defective NADPH oxidase so bacteria wil stay alive inside the phagocytes as there is no respiratory burst
LAD1/2 deficiency…
problems with migration so the cells do not stop at the site of infection and requires a lot of energy
LAD-1: problem with adhesion
LAD-2: Siayl Lewisx binds to L-selectin so there is a problem with rolling
HIV…
The CD4+ T-helper lymphocytes are depleted which weakens the immune system so the body can not stop infections or remove cancer cells