components of the immune system Flashcards
(50 cards)
1
Q
define immunology
A
study of the immune system
2
Q
define immune system
A
a system of cells, tissues and their soluble products that recognise, attack and destroy entities that could endanger health
3
Q
define immunity
A
normal functioning of the immune system. Latin ‘immunitas’ = ‘exempt from’. Survivors of disease said to have become exempt from the disease, or ‘immune’
4
Q
define inflammation
A
A series of reactions that brings cells and molecules of the immune system to sites of infection or damage
5
Q
name some anatomical and physiological barriers of the immune system.
A
- conjunctivia of the eye
- mucus
- flushing action in urinary tracts
- lysosomes in tears and saliva
- cilia lining in trachea
- skin
- acid in stomach
- organisms in gut, vagina and on skin
6
Q
what are the 3 catagories of barriers and give a couple of examples from each.
A
mechanical - epithelial cells joined by tight junctions - mucus movement by cilia - tears
chemical - fatty acids - low ph - enzymes - surfactant
microbiology - normal microbiota (community of microorganisms)
7
Q
define haematopoesis.
A
“The commitment and differentiation processes that leads to the formation of all blood cells from pluripotent haematopoietic stem cells.”
8
Q
outline what a cytokine is and its function
A
- proteins secreted by immune and non-immune cells
- signalling molecules that act via specific receptors on the target cell surface coordinating immune responses and other cellular processes
9
Q
Cytokines are involved in a wide range of physiological processes, name some of these.
A
Immune response
Wound healing
Inflammation
Cell growth and differentiation
10
Q
name the different cytokine families
A
- interleukins
- interferons
- tumour necrosis factors
- colony stimulating factors
- chemokines
- growth factors
- pro - inflammatory
- anti - inflammatory
- Th subset-specific cytokines
11
Q
what are interleukins
A
- type of cytokine - over 40 of them
- mediators between lymphocytes and leukocytes
- proteins or glycoproteins
- produced by various cells including T and B cells, macrophages, dendritic cells and epithelial cells
- bind to specific cell receptors which initiate intrasignalling pathways
- interleukins have a wide range of functions, including:
- pro-inflammatory - stimulate immune responces to infections or injury
- anti-inflammatory - limits macrophage, dendritic activity and inhibits T cell activation
- growth and development of immune cells - supports proliferation, differentiation and survival of immune cells
- chemotaxic - attracts neutroiphills to infection sites
- shapes immune responces based on the type of pathogen
12
Q
what are interferons
A
- family of cytokines
- glycoproteins
- they are released when PAMPs bind to PRRs and they then bind to target cell - they activate the JAK-STAT pathway, leading to transcription of genes which produce antiviral proteins, enhance antigen presentation and modulate immune cell activity
- 3 types:
type 1
type 11
type 111
function:
- antiviral defence
- enhance phagocytosis and immune cell recruitment to site of infection and promote NK cell cytotoxicity
- tumour surveilance
- shapes adaptive immunity - upregulate MHC expression
13
Q
macrophages
A
- phagocytic cells
- move across capilary walls into site of infection
- release cytokines
- engulf and destroy pathogens and dead cells
14
Q
mast cells
A
- in mucus membranes and connective tissues
- important for wound healing and defence against pathogens
- release cytokines and granules to create inflammatory cascade
15
Q
neutrophills
A
- phagocytic cells classified as granulocytes
- stops toxic bacteria and fungi from proliferating and kills them
- first responders to infection
- phagocytose bacteria
16
Q
eosinophills
A
- target multicellular parasites and involved in allergic reactions
- secrete toxic proteins and free radicals to kill pathogens
- this also causes tissue damage during allergic reactions
- found in thymus, gi tract, overies, uterus, spleen and lymph nodes
17
Q
basophills
A
- attack multicellular parasites
- release histamine
18
Q
natural killer cells
A
- don’t attack pathogens directly
- destroy infected host cells and cancers
- non-antigen presenting
19
Q
dendritic cells
A
- antigen-presenting
20
Q
B cell
A
- coordinates and activates other immune cells
21
Q
cytotoxic T cell
A
- kills infected cells and cancer cells
22
Q
antibodies
A
- glycoproteins produced by B cells that bind to antigens
23
Q
cytokines
A
- small signalling molecules
- influence cell growth, differentiation and activation
23
Q
chemokines
A
- specialised role
- attracts immune cells to sites of infection or inflammation
- facilitate the targeted movement of immune cells
24
interleukins
- type of cytokine
- either pro or anti-inflammatory
- can cause cells to divide, differentiate and secrete other factors
25
interferons
- induces antiviral resistance in uninfected cells
- limits the spread of viral infection
26
tumour necrosis factor
- mediate inflammation and cytotoxic reactions
27
colony stimulating factors
- involved in directing the division and differenciation on bone marrow stem cells
28
chemokines
- chemotactic cytokines
- direct movement of cells from the bloodstream into the tissues or lymph organs by binding to specific receptors
- classes of chemokines defined by arrangement of cysteine residues
- majority if classes - CC and CXC
29
outline the role of interleukin-1
- outlines vascular endothelium
- activates lymphocytes
- increases access of effector cells
30
outline the role of tumour necrosis factor.
- activates vascular endothelium
- increrases vascular permeability - leads to more IgG compliments, immune cells to tissues and drainage to lymph nodes
31
name the humoral components and their function.
- coagulation system - clot acts to immobilise microorganisms and prevent entry into blood and lymph
- complement system - enhances the ability of antibodies and phagocytic cells to clear microbes and damaged cells from an organism
- fibrinolytic system - decompose clot when no longer required promoting wound healing
- kinin system - widen blood vessel lumen and increase capillary permeability thus increasing supply of soluble and cellular material to site of infection
32
what organ secretes the plasma proteins used in the complement cascade?
liver
33
what do the 3 complement pathways lead to ultimately?
- activation of C3b
34
what are the 3 activation pathways of the compliment cascade and briefly outline them?
- classical - IgG and IgM binds to the antigen of microbes
- alternative - C3b binds to the surface of microbes
- lectin - activated by mannose binding to lectin that binds mannose to microbe surfaces
35
what does the compliment cascade result in?
- attracts more leukocytes to site of infection
- opsonisation enhancement - binds invading organisms to potentiate phagocytosis
- direct lysis - directly puncture membranes of pathogens leading to cell rupture and destruction - MAC
36
outline the process of what happens during the classical pathway.
- IgG / IgM bind to antigen
- C1, C4, C2, C3 bind to antibody
- C3 goes into C3a and C3b
- C3b stays attached to the cascade, C3a breaks off
- C3b, C6, C7, C8, C9 bind all bind
- later this complex breaks away and forms a circular channel
37
in the classical pathway what are C3a and C5a used for?
- They are activated by proteases, which are released by circulating mast cells
- they then act as cytokines, amplifying the immune response
38
outline the process of the alternative pathway.
- C3 spontaneously splits
- factor B binds to it
- factor D cleaves it
- producing factor C3a and C3b
- C3b binds to pathogens
- this serves as signalling molecule for opsonin receptor on leukocytes - leading to engulfement
- also leads to the other proteins to bind forming MAC for lysis
39
outline the process of the lectin pathway.
- mamose binds to the surface of pathogens
- C4b, C2b, C3b, C5b are all formed from original molecules and they all bind
C6, C7, C8, C9 then all attach to this complex and will later form MAC - lysis
- when it does C3b is exposed, an opsonin receptor on leukocytes will bind to this - promoting phagocytosis
40
what are the cardinal signs of inflammation?
- pain
- heat
- readness
- swelling
- loss of function
41
what are the steps of the required inflammatory response?
Required response:
Stop bleeding (coagulation system)
Acute inflammation (leukocyte recruitment - kinin system and chemotaxis)
Kill pathogens, neutralise toxins, limit pathogen spread
Clear pathogens/dead cells (phagocytosis)
Proliferation of cells to repair damage
Remove blood clot (fibrinolytic system) – remodel extracellular matrix
Re-establish normal structure/function of tissue
42
outline the differences between monocytes and macrophages.
a monocyte is an immature macrophage cell which is in the blood, as soon as this leaves the blood, it differentiates into a macrophage
43
what secretes cytokines and for what reasons?
immunity:
- T cells
- B cells
- macrophages
- dendritic cells
- neutrophills
- eosinophills
- basophills
- natural killer cells
healing and tissue repair:
- endothelial cells
- fibroblasts
- adipocytes
- muscle cells
44
what is tumor necrosis factor
- trimeric protein
- produced and secreted predominantly by macrophages, T cells, NK cells predominantly but can also be produced by immune and non-immune cells such as the endothelium
- secreted when toll-like receptors identify the pathogen, by DAMPS, can be stimulated by IL or interferons, or even by antigen presentation and cross talk between immune cells
functions:
- induces apoptosis
- enhanced macrophage activation
- stimulate IL release
- promotes ccellular survival and tissue repair
- role in tumour surveilance
- acts on the hypothalamus causing systemic effects
45
whats colony-stimulating factor
- cytokines
- regulate the production, differentiation and function of hematopoietic cells
types:
- granulocyte colony-stimulating factor
- macrophage colony-stimulating factor
- granulocyte-macrophage colony-stimulating factoe
- interleukin-3
secreted by:
- endothelial cells
- fibroblasts
- all wbc
- osteoblasts
functions:
- hematopoiesis
- immune response
- tissue repair and inflammation
46
what are chemokines
- specialised subset of cytokines
- allow chemotaxis
secreted by:
- macrophages
- dendritic cells
- T cells
- B cells
- mast cells
- fibroblasts
- endothelial cells
- epithelial cells
functions:
- chemotaxis
- establishes gradient of immune cells in lymphoid tissue
- immune surveilance
- angiogenesis
- antiviral and antitumour responces
- inflammatory responce - drives accumulation of leukocytes
47
what are growth factors
- regulate cell growth, differentiation, survival, and tissue repair
types:
- epidermal growth factors
- platelet-derived growth factor
- fibroblast growth factor
secreted by:
- immune cells
- endothelial cells
- fibroblasts
- platelets
- epithelial cells
functions:
- cell proliferation and differentiation
- tissue repair and wound healing
- angiogenesis
- immune responce modulation
- cellular survival
- inflammation control
48
what are pro-inflammatory cytokines?
- cytokines that amplify the inflammatory response
- typically produced by immune cells in response to injury or infection
- promotes inflammation, cytotaxis
what are they?
- tumour necrosis factor alpha
- interleukin-1
- interleukin-6
- interleukin-8
- interleukin-12
- interferon-gamma
- granulocyte-macrophage colony-stimulating factor
functions:
- induce fever
- recruit immune cells
- activate immune cells
- enhance antigen presentation
- tissue repair and regeneration
- support Th1 responces
49
what are anti-inflammatory cytokines?
- regulate and resolve inflammation
- counteract the effects of pro-inflammatory cytokines and help to restore homeostasis
what are they?
- interleukin-10
- transforming growth factor-beta
- interleukin-4
- interleukin-13
- interleukin- 35
secreted by:
- reg T cells
- macrophages
- dendritic cells
- B cells
- Th2 cells
functions:
- supresses pro-inflammatory cytokines
- regulating T cell responces
- enhancing regulatory T cell activity
- supporting tissue repair and healing
- resolving inflammation
