Adaptive immunity Flashcards
Where are low levels of complement system proteins normally found
plasma
extracellular fluids
Where can complement system proteins be activated
once in tissues
What occurs once the complement system is activated
cascade of chemical reactions
What can occur as result of the chemical of cascade reactions once the complement system is activated
Opsonisation of pathogens
direct pathogen killing
acute inflammation
leukocyte recruitment
What leukocyte is commonly recruited in response to acute inflammation
neutrophil
What is the inactive precursor of the complement system
C3
What are the 3 methods of cleaving c3
classical pathway
MBL pathway
alternative pathway
what is formed as result of cleaving c3
C3b and C3a
Why is the MBL pathway at targeting bacterium
MBL binds to mannose which is not a self molecule, can only be found on bacteria
What happens when MBL binds to mannose
produces another C3 converting enzyme which can result in activation of the alternative pathway
What ensures that the amplification loop can only begin when pathogens are around
C3b is produced which is unstable
tissue cells have inhibitors and so loop can only be activated when pathogens around
What happens when c3b binds to a pathogens surface
C5 is cleaved into C5b and C5a
What is the function of C5b
Builds membrane attack complex (MAC) which punctures pathogen cells
What is the function of C5a
promote inflammation
What is the function of C3a
promote inflammation via mast cells of histamine
What is responsible for activating the complement system
acute phase response in the liver
Which adaptive immune cell is responsible for humoral immune responses
B cells
Which adaptive immune cell is responsible for cellular immune responses
T cells
Which adaptive immune cell is responsible for killing extracellular pathogens
B cells
Which adaptive immune cell is responsible for defence against intracellular pathogens
T cells
What are the 2 main types of T cell
CD4+
CD8+
What is the main function of CD4+T cells
Key regulators of the immune system via cytokines
what is the main function of CD8+T cells
kill virally infected body cells (the “muscle” of T cells)
How do adaptive immune cells detect invading pathogens
recognise antigens via antigen receptors (specific)
What are B cell receptors
antibodies
What is the structure of a B cell receptor (BCR)
polypeptide chains
2 heavy chains
2 light chains
unique variable region
What are the 2 forms of antibody
membrane bound
soluble
What is the humoral immune response needed for
production of soluble antibodies
What do B cell antibodies bind to
soluble antigens
What do T cell receptors bind to
peptide antigens
What does the T cell antigen receptor consist of
alpha chain
beta chain
What is needed for T cell receptors to bind to antigens
MHC molecules must present the antigen to the receptor
What are the examples of soluble antigens B cell receptors can respond to
lipid antigen
protein antigen
carbohydrate antigens
Which class of MHC presents antigens to CD8
MHC 1
Which class of MHC present antigens to CD4
MHC 2
Where is MHC 1 expressed
on all nucleated cells
Where is MHC 2 expressed
only on professional antigen presenting cells (APCs)
dendritic cells
macrophages
Where does the adaptive immune response occur
secondary lymphoid tissues
How do T and B cells enter lymph nodes
high endothelial venue
How do B cells encounter antigens
soluble antigens are released by phagocytes which drain through lymphatic vessels
How do T cells encounter antigens
dendritic cells display peptides derived from pathogens on their surface
Do dendritic cells express MHC 1 and MHC 2
yes
When do T cells replicate
once antigen is bound
