immune system 2 Flashcards
what is the function of bacterial LPS
activate toll like receptors in macrophages
how does signaling work in TLR4 and what is its function
TLR4 expressed in macrophages detects LPS. Bacterium binding to the receptor stimulates a signal transduction pathway that activates transcription of genes encoding pro inflammatory cytokines
also expressed in dendric cells where the signal transduction process stimulates their maturation
signal transduction of TLR7 in ssRNA virus
TLR7 detects ssRNA and signal to activate signaling transduction inside the cells
this leads to the production of alpha and beta IFN which have anti-viral proteins
what is the function of interferon response (IFN)
induce resistance to viral replication in all cells
increase expression for receptors on NK cells
activate NK cells to kill virus infected cells
what is the function of natural killers (NK cells)
activates by cytokines IFN alpha and beta
killing cells infected by viruses
can contain a viral infection until adaptive response kicks in
NK cells produce gamma IFN
a deficiency of natural killers can lead to viral infections and increased risk of herpes
how do Natural killer cells induce apoptosis
IFN binds to its receptors and activate NK cells
NK cells proliferate and differentiate in effector NK cells
these effector NK cells kill a virus by inducing apoptosis
innate immune response in bacteria and virus
they both have immediate innate immune response which are barriers, anti microbal peptides and complement. they both have cytokines production and inflammation
induced innate immune response in bacteria TLR: 1,2,4,5,9
4: phagocytosis (macrophages and neutrophils)
induced innate immune response in virus
TLR: 3,7,8,9
7: interferons type 1 (alpha and beta) and NK cells
what is the structure of an antibody molecule
Y shaped
4 polypeptide chains
2 identical heavy chains and 2 identical light chains
each chain have a variable (V) and a constant (C) region
antibody interactions hypervariable regions and complimentary determining regions
- There are 3 CDRs from each of the heavy and
light chains (CDR 1-2-3) - The difference in the CDRs between different
antibodies create both specificities and diversity of antigen-binding sites - Both heavy and light chains contribute
what are the 3 anti bacterial specific functions of antibodies
opsonization
neutralization
complement activation
antibodies specific immunity
- Neutralise free virus (prevent entry into and spread between cells)
– Can prevent spread within the body (e.g. poliovirus) or protect mucosal surfaces against reinfection (e.g. ‘flu’)
– Influenza virus binds on cell surfaces through a protein called hemagglutinin. Neutralising
antibodies coat the virus, inhibit its attachment and prevent infection - Opsonise to increase phagocytosis
- Activate complement leading to lysis
(enveloped viruses)
specific functions if classes of antibodies
IgM
* First antibody to be produced
* Give the primary response
* Defense of tissues and prevention of septicemia
IgG
* Give the secondary response (more specific and stronger)
* Defense of tissues and prevention of septicemia
IgA
* Prevents septicemia
* Protects surfaces of the mucosal epithelium
* Present in maternal milk to give protection to infants
IgE
* Defense against parasite infections
* Important in allergies
what is the function of monoclonal antibodies
immunosuppressive
to prevent transplantation rejection
to treat autoimmune disease
to reduce immune response
produced in mice
what is the mechanism of depleting action of monoclonal antibodies
monoclonal IgG antibodies binds to target cells and cause them to immune cells such as macrophages and NK cells which have Fc receptors
target cells are killed by phagocytosis or antibody dependent cell-mediated cytotoxicity
what is the mechanism of action of non depleting antibodies
block the function of target protiens without killing the cell that bears it
