IMI1: sensing damage protecting our bodies Flashcards
what cells are lymphoid cells?
T cells, B cells and NK cells
what are the other major classes of cells?
myeloid cells (e.g. macrophages) mast cells DCs neutrophils basophils eosinophils
what are NK cells?
large cytotoxic lymphocytes that patrol the blood for virally-infected of damaged cells which they are able to recognise despite lacking variable receptors like the ones found on B and T cells
in what type of immunity is NK cells involved in?
it is involved in the innate immunity
what are cytokines?
small polypeptides that are used as messengers in the immune system
do we have the same number of microbes than body cells?
approximately yes
are the microbes living in our body harmful?
no they are harmless. they live in symbiosis with us
what is a microbiome?
microbiome is the genetic material of all of the microbes
is the microbiome essential?
yes it is vital for the correct absorption of nutrients
what are commensal bacteria?
bacterias and other microorganisms that act on host’s immune system to induce protective responses that prevent colonisation and invasion by pathogens
what is the first line of defence of our body?
physical barrier: skin, mucous membranes, secretion (e.g. tears)
what is the second line of defence?
innate immune system
what does the innate immune system have to do?
needs to:
- defect
- deflect
- destroy
is the action of the innate immune system broad or specific?
broad
what is the third line of defence?
adaptive immune system
is the adaptive immune system always deployed?
no, it is only deployed if it is absolutely necessary
what are the organs of the immune system?
adenoids tonsils thymus BM bronchial-associated lymphoid tissue axillary lymph nodes lymph nodes spleen payer's patches inguinal lymph nodes appendix lymphatic vessels
how doe the innate immune system recognise the myriad of pathogens?
1st, the immune system recognise if something is harmless or dangerous:
the first cells pathogens encounter after physical barrier are resident macrophages that are present in all tissue
what is phagocytosis?
process done by phagocytes where they gobble up pathogens or damaged cells and kill them using proteolytic enzymes and reactive oxygen species (ROS)
how do macrophages recognise pathogens or damaged cells?
pathogens have structural features essential for their survival –> PAMPs (pathogen-associated molecular patterns)
damaged cells –> DAMPs (damage-associated molecular patterns)
what are APC (=antigen presenting cells)? what do they do?
DCs and macrophages
they present antigen to T cells
what are the 2 signals that the T cells need to get activated?
- the antigen needs to be presented by major histocompatibility complex (MHC)
- molecules on the APC that are called CD80 and CD86
what are PRRs (pattern recognition receptors)?
family of receptors that recognise PAMPs and that control the activation of CD80 and CD86
what are the 2 main groups of PRRs? and what do they do?
- signalling PRRs –> initiate signalling cascades
- phagocytic receptors –> trigger phagocytosis
can signalling PRRs and phagocytic PRRs be soluble and cell-associated PRRs?
yes
do each cell type express all innate receptors?
no, each cell type expresses just a few types
what is cellular heterogeneity? how does it help cells?
certain functional immune cell type express different combinations of PRRs
it increases cell’s ability to identify non-self antigens or damaged cells
what are other phagocytic receptors that macrophages express?
complement receptors and scavenger receptors
what are the different types of cytokines?
- 40 interleukins (ILs)
- chemotactic chemokines
- antiviral interferons (IFNs)
what are the manners in which cytokines act?
autocrine, paracrine or endocrine manner
what does it mean for cytokines to have pleiotropic functions?
it means that they behave differently in different cells types and thus can have many different functions
what do cytokines do in endothelium?
induce cell contraction and cytokine secretion
what do cytokines do in macrophages?
induce cell activation
what do cytokines do in DCs?
induce cell differentiation
what do chemokine do in phagocytes?
induce cell migration
what are the different pro-inflammatory cytokines? and what do they do?
IL-1beta, IL-6, IL-12, CXCL8 and TNF-alpha
they induce inflammation
what dies inflammation causes?
causes local redness, swelling, less blood flow and vascular permeability
what does permeability allow?
it allows the exit of neutrophils and other leukocytes from the blood and subsequent proliferation of NK cells
macrophages release all types of pro-inflammatory cytokines. what do they each do?
IL-1beta and TNF-alpha –> induce blood vessels to become more permeable, enabling effector cells and fluid containing soluble effector molecules to enter the infected tissue
IL-6 –> induces fat and muscle cells to metabolise, make heat and raise the temperature in the infected tissue
CXCL8 –> recruits neutrophils from the blood and guides them to the infected tissue
IL-12 –> recruits and activates NK cells that in turn secret cytokines that strengthen the macrophages’ response to infection
where can we find PRRs?
macrophages, DCs, NK cells, mast cells and neutrophils
how is the precise immune response determined?
it is determined by the combination of PRRs
what are the different PRRs?
CLR, NLR, TLR, RLR, cGAs and STING
