A brief overview of the immune system Flashcards
What is the immune system?
A network of cells and tissues that are constantly patrolling our body for invaders spread out in the body- involves many types of cells, organs and proteins
Characteristics of the innate immune system
First line of defence
non specific
local
no memory response
Characteristics of the adaptive immune system
T and B cells
takes a while to kick in- 7 days or sp
specific for the antigens
forms a memory response
What is the complement system?
A cascade of proteins circulating in the blood
3 pathways- triggered by different stimuli
ultimate aim= form a membrane attack complex- lysis of pathogens and cells
What are cytokines and what do they do?
They are peptides that have a fundamental role in communication in the immune system, and in allowing the I.S and host tissue cells to exchange information
IL-6, IL-12 and TNFalpha
What local and systemic effects can cytokines have?
local= stimulate the vasculature, enhanced permeability and expression of adhesion molecules systemic= IL1/6- induce fever- raise core temperature of the body
What are the granulocytes?
Neutrophils, eosinophils and basophils
3 characteristics of neutrophils?
They’re phagocytic
they can form a neutrophil extracellular trap with their DNA
hypoxia activates them
What are the characteristics of monocytes/macrophages?
Monocytes are the circulatory cells, once they enter tissue they differentiate into macrophages
they’re phagocytic cells
they express pattern recognition receptors
if bacteria is covered in complement particles/bound to an antibody- macrophages can bind to them
they can present extracellular proteins on the MHC2 complex
one of the few cells that express MHC2
Whats the significance of B cells and antibodies in the tumour specific response?
ABs aren’t heavily involved at all
sometimes suppressor B cells found in the tumour
T cells have much more of a role in the response
What are the characteristics of dendritic cells?
The most important antigen presenting cell
express MHC2
Only cell that can activate naive T cells- educate them on what pathogens are
have a set of pattern recognition receptors- like TLR4- TLR4 activation= inflammatory cytokine production and activation of the innate immune system
Characteristics of NK cells?
Part of the innate immune system
very important in tumour recognition
target and kills cells via perforin and granzyme b
dual activation process
inhibitory receptor= Ly49- stops a NK cell from killing the cell that activated it
infiltration of tumour cells by NK cells= good prognosis
What are the characteristics of T cells?
Extremely important in tumour biology
mediators of cellular immunity
express antigen specific receptors- TCR
TH1 cells can be beneficial to tumours in the tumour environment
T reg cells are also beneficial in the tumour environment- they have a general suppressor effect on the I.S
How does the tumour stay away from immune cells?
Makes physical barriers- using vasculature etc
wants to escape CD8+ cells- which recognise tumour cells
