Immunology Flashcards
name three things that can manipulate the immune system
immunisation
anti-inflammatory/immunosuppressive drugs
cancer immunotherapy
what are the two main divisions of the immune system?
innate and adaptive/acquired
which type of immunity is present from birth?
innate
which type of immunity is generally non-specific?
innate
which type of immunity provides a rapid response?
innate
what is the first line of defence against infection?
the chemical and physical barriers of the innate immune system
name four soluble factors produced by the innate immune system
cytokines
acute phase proteins
inflammatory mediators
complement proteins
name four immune cells produced by the innate immune system
macrophages
mast cells
NK cells
neutrophils
how is adaptive immunity acquired?
it is induced by the presence of foreign material
which type of immunity is usually specific to a pathogen?
adaptive immunity
which type of immunity produces a slow response?
adaptive immunity
name two soluble factors produced by the adaptive immune system
cytokines
antibodies
name two immune cells of the adaptive immune response
B cells
T cells
name three things that provide a barrier to infection
skin
mucous
commensal bacteria
what is the most important barrier to infection?
the skin
what type of barrier is the skin?
a physical and physiological barrier
name three ways in which the skin keeps pathogens out of the body
cells are thick and tightly packed
has low pH and low oxygen tension
produces secretions against infections
where does the skin produce secretions against infections from?
the sebaceous glands
name four secretions against infection secreted by the skin
hydrophobic oils
lysozyme
ammonia
antimicrobial peptides
where in the body is lined with mucous membranes?
all body cavities that come into contact with the outside environment
how does mucous create a barrier to infection?
it traps bacteria which are then removed by ciliated cells
what are commensal bacteria?
bacteria that normally reside at epithelial surfaces
how do commensal bacteria create a barrier to infection?
they compete with pathogens for scarce resources and produce secretions that inhibit the growth of many pathogens
when are the innate immune responses initiated?
when physical barriers are breached and pathogens invade
what three ways can pathogens be ingested by macrophages?
pinocytosis
receptor mediated endocytosis
phagocytosis
what is pinocytosis?
ingestion of fluid surrounding cells
what is receptor mediated endocytosis?
internalisation of molecules bound to membrane receptors
what facilitates the ingestion of pathogens by immune cells?
opsonisation
what is opsonisation?
the coating of pathogens by soluble factors (called opsonins) to enhance phagocytosis
give four examples of opsonins
C3b
CRP
IgG
IgM
what cell is activated if a pathogen is too large to be ingested by phagocytes?
mast cells
what do mast cells do when a pathogen binds?
undergo degranulation
what is degranulation?
the release of pro-inflammatory substances
what is a PRR and what cells are they found on?
pattern recognition receptor
immune cells
what is a PAMP and what cells are they found on?
pathogen associated molecular patterns
pathogens
give four examples of pro-inflammatory mediators
nitric oxide
prostaglandins
histamine
TNF a
name three phagocytic cells
macrophages
dendritic cells
neutrophils
what three cells are tissue resident innate immune cells?
macrophages
dendritic cells
mast cells
what does the complement system do when activated?
creates a cascade of chemical reactions that promote an immune response
what four things are triggered by activation of the complement system?
opsonisation
pathogen killing
inflammation
leukocyte recruitment
what are the three possible complement pathways?
classical
mannose binding lectin
alternative
what is the main step in the complement system?
C3 converted to C3b and C3a
what do C3b and C3a activate?
downstream complement proteins
what is C3?
an acute phase protein
what cells express mannose?
pathogens only, which is why it activates the complement system
how does MBL activate the complement system?
it activates C3 convertase which is needed to convert C3 to C3b and C3a
what role does C3b play in the complement system?
it activates an amplification loop which further activates C3 convertase to activate the pathway via the alternative system
what activates the downstream complement pathway and how?
active C3b associates with other proteins and produces a C5 convertase
what does C5 convertase do?
cleaves inactive C5 into C5a and C5b
what does active C5b do?
associates with other complement proteins to produce membrane attack complex (MAC)
what is membrane attack complex?
a pore forming channel which inserts into the pathogens membrane/wall
how does MAC destroy pathogens?
extracellular salts and water enter the pathogen via the pore MAC creates, causing it to swell and burst
name two anaphylatoxins
C3a
C5a
what do anaphalotoxins do?
promote changes in vasculature, inflammation and leukocyte recruitment by activating mast cells and acting on blood vessels
what can C3b be used as?
a powerful opsonin
what are the three killing mechanisms of a neutrophil?
phagocytosis
degranulation
NETs
what two methods do neutrophils use to kill pathogens in phagocytosis?
phagolysosomal killing
ROS dependent killing
what is neutrophil degranulation?
release of anti-bacterial proteins directly into the e extracellular matrix
what is a negative to neutrophil degranulation?
can cause tissue damage and inflammation
what does NET stand for in neutrophilic killing?
neutrophil extracellular traps
how do NETs work?
neutrophils release them and they trap and kill pathogens
what body cells mediate the acute phase response and how?
hepatocytes
produce many of the acute phase proteins
what is CRP?
C reactive protein
what are two roles of CRP?
prime bacteria for destruction by the complement system
helpful for diagnosing inflammation
what type of antigens to T cells recognise?
only peptide antigens
what is the antigen receptor on a T cell called?
the T cell receptor (TCR)
what is the TCR?
a membrane bound protein heterodimer, made of an alpha chain and a beta chain
what are the two main types of T cells?
CD4+ T cells
CD8+ T cells
what do CD4+ T cells do?
regulate the immune system
what do CD8+ T cells do?
kill virally infected body cells
when can a T cell recognise a peptide antigen?
only when it is presented to the TCR on an MHC molecule
what is an MHC molecule?
major histocompatibility complex molecule
what do T cells do once activated?
they clonally proliferate and differentiate into different types of effector cells
what do naive CD4+ T cells proliferate into?
Th0 cells
what four types of cells can a Th0 cell differentiate into?
Th1
Th2
Tfh
regulatory T cells
what is a Tfh cell?
a T follicular helper cell
what do activated CD8+ cells differentiate into?
cytotoxic T cells
what is the function of MHC molecules?
they display antigens to T cells
what is another name for an MHC molecule?
HLA (human leukocyte antigens)
what are the two types of MHC molecules?
class I MHC and class II MHC
what cells express class I MHC molecules?
all nucleated cells
what cells do MHC I molecules present antigens to?
CD8+ T cells
what cells express class II MHC molecules?
antigen presenting cells
what cells do MHC II molecules present antigens to?
CD4+ T cells
what cell is the bridge between the innate and acquired immune systems?
dendritic cells
what is the main function of a dendritic cell?
presents antigens to T cells
where do B cells mature?
the bone marrow
what cell is responsible for the humoral immune response?
B cells
where do T cells mature?
the thymus
what is an antibody?
a protein that binds to a specific antigen
what is an antibody made of?
two light chains and two heavy chains
what induces the adaptive immune responses?
antigens
what is an antigen?
any substance which can cause an adaptive immune response by activating B/T cells
what is another name for antibodies?
immunoglobulins
name the five classes of antibodies
IgM IgG IgA IgE IgD
where do lymphocytes develop originally?
the bone marrow
what is monitored at lymph nodes?
tissue for infection
what is monitored by the spleen?
blood for infection
what is monitored by MALT?
GI infections
what is MALT?
mucosal associated lymphoid tissue
