Immune Response Flashcards
Innate immune system
Responds quickly to invaders as first line of defence - prevents the entry of m/o
No adaption in response
Response is the same on exposure
Acts to confine invader and stop spread and stimulate adaptive IR
Adaptive immune system
Responds more slowly
Response adapts to invaders encountered
Response much quicker and stronger upon re exposure
Complement function
Consists of 20 serum proteins that are produced in the liver and circulate in bloodserum . Help facilitate innate ir
- Directly cause damage to cell membrane if invading pathogen
- Create a chemotactic gradient - causing stimulation and activation of phagocytes. Active phagocytes ingest invading microbe.
- Invade /attach to surface of bacteria - creates a signpost towards innate IR cells - to make them more visible (opsonization).
2 phases of viral life cycle
Lysis - part of the life cycle where the virus is actively shedding viral particles and is infective.
Latent infections- viral genome is incorporated into the host cell and DNA remains dormknt. Under conditions of stress becomes activated , starts shedding viral particles and can become infectious again.
1st line of response to viruses
Innate IR
up regulation of some chemicals;
Interferons (IFN)- stimulates the inhibition of viral replication - INTRACELLULAR RESPONSE
NK cells- cytotoxic for infected cells
Activation of macrophages
2nd line of response to viruses
Acquired immune response
Antibodies and complement to limit vital spread
T cells mediate viral immunity in many ways
4 ways IFN can stimulate inhibition of viral synthesis
Cell apoptosis
Inhibit protein synthesis
Degrades viral mRNA
Block viral transcription
How do NK cells kill a virus
This interact with a special classs of angtigen presentation molecule , found on surface of infected cells called MHC class 1, Causing their destruction
They are also a primary mediator of antibody dependent medicated cytotoxicity (ADCC)
NK when bound to viral infected cells release cytokines such as IFN gamma which promote apoptosis through performing and granzyme secretion
3 levels macrophages act on.
- phagocytosis of virus and virus infected cells
- Killing of virus infected cells - called a phagolysosome- producing a hostile lytic environment
- Production of anti viral molecules such as TNFa abd nitric oxide.
What cellls does the adaptive IR produce
T cells - cytotoxic T lymphocytes (CTLs) - directly Kill infected cell
Helper at cells - amplification of IR
antiviral antibodies
What is a T cell receptor
TCR is a molecule found on the surface of T cells that is responsible for recognising antigens bound to MHC molecules.
MHC class 1 cells
Expressed on virtually all cell types
Process and present antigen fragments for activation of CD8+ abd CTLs cells
MHC class 2
Found primarily on phagocytic cells and activate CD4+ helper at cells and promote and antibody response
2 methods by which CD8+ cytotoxic T lymphocytes kill an infected cell
Secretion of granules containing lytic enzymes called granzymes and specialist proteins called perforin that induce a pore formation on the surface of the cell. The pore formation allows entry of granzymes and lytic enzymes that activate destruction of that particular cell.
Second is through the interaction of cell surface receptors. CD8+ cytotoxic T lymphocyte contains what is refered to as the fast ligand and the fast receptor aka the death receptor . In this part iPad instance of an infected cell , that cell upregulates the expression of the fast receptor and as a result the fast ligand , Which is expressed on the surface of the Cd8+ cell , interacts, giving an extracellular ligand receptor interaction , triggering cellular apoptosis
