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Medicine Unit 3 > Mucosal immunity > Flashcards

Mucosal immunity Flashcards

1
Q

what are primary lymphoid organs

A

sites where b and T cells are made and matured

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2
Q

where are the primary lymphoid organs

A

bone marrow
thymus

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3
Q

what are the secondary lymphoid organs

A

sites where b and T cells can recognise antigen and become activated to fight infection or cancer

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4
Q

where are the secondary lymphoid organs

A

lymph nodes
spleen
mucosa associated lymphoid tissues/MALTs

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5
Q

capsulated lymphoid tissues

A

lymph nodes
spleen

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6
Q

non-capsulated lymphoid organs

A

mucosa associated lymphoid tissues
50% of bodies lymphoid tissue

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7
Q

what are capsulated lymphoid tissues designed for

A

to control what comes in from outside and keep things trapped inside

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8
Q

function of the spleen

A

as a filter for blood
not supplied by lymphatic vessels
responds to systemic infections
more lymphocytes flow through spleen than all lymph nodes at any given time

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9
Q

how do antigens and lymphocytes enter the spleen

A

via the splenic artery

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10
Q

2 distinct regions of the spleen

A

white pulp
red pulp
separated by a diffuse marginal zone

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11
Q

differences between lymph nodes and spleen

A

lymphocytes enter via artery
and immune response occurs in the periarteriolar lymphoid sheath

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12
Q

red pulp function

A

contains mainly macrophages, RBCs and some lymphocytes
old and damaged RBCs are phagocytose in the red pulp

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13
Q

white pulp function

A

mainly surrounds arteries in the spleen
forms periarteriolar lymphoid sheath
predominantly T cells

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14
Q

marginal zone function

A

at the edge of the PALS
made of mainly B cells
contain primary lymphoid follicles

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15
Q

process of immune response in the spleen

A

foreign antigen carried into the spleen from the splenic artery into the marginal zone and captured by dendritic cells
dendritic cells and T cells move to the PALS from the splenic artery
PALS the dendritic activate T helper cells
active T helper cells activate B cells and activated B and helper T move to the primary follicles in the marginal zone
leads to the production of a secondary follicle with germinal centre

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16
Q

lymph nodes

A

clustered at junctions of lymphatic channels, entrap pathogens entering the lymphatic system from the tissues
bean-shaped structures, comprising a mesh-like reticular framework , packed with lymphocytes, macrophages and dendritic cells

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17
Q

lymph nodes and immune response

A

lymph flows into the node through lymphatic channels, empty into the sub capsular space carrying APCs and free antigens
lymph percolate inwards, allows phagocytic cells to entrap any bacteria in the lymphatic fluid
a single efferent vessel leaves the lymph node
lymph nodes enlarge when immune response occurs

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18
Q

fluid in the efferent lymphatic vessel

A

contains antibodies and 50x higher concentration of lymphocytes due to proliferation of lymphocytes within the node

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19
Q

production of secondary follicle in lymph node

A

antigen and APC from tissue travel to lymph node in the lymphatic fluid
antigens processed by resident dendritic cells in the paracortex
dendritic cells and B cells activate antigen specific T helper cells
B cells also activated in the paracortex by antigen directly via the BCR and any helper T cells
activated B and helper T form foci with proliferating B cells
B cells and helper T cells migrate to primary follicles of the cortex and interact with follicular dendritic cells
production of secondary follicle with germinal centre and production of plasma cells

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20
Q

what are lymphoid follicles

A

collections of lymphocytes and dendritic cells, in all secondary lymphoid tissue

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21
Q

primary follicles

A

collection of mainly inactive B cells, macrophages and follicular dendritic cells

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22
Q

what occurs when germinal centres are formed

A

the follicle is called a secondary follicle

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23
Q

what happens when activate dB cells and helper T cells move into follicles

A

proliferate forming germinal centres

24
Q

germinal centres

A

B cells proliferate and undergo somatic hypermutation to make better antibodies
inactive B cells pushed towards age to form mantle zone
B cells surrounded by cuff of T helper cells

25
Q

what is occurring in the dark zone

A

cell proliferation

26
Q

what is occurring in the light zone

A

cell death

27
Q

somatic hypermutation

A

immunoglobulin gene sequences are further mutated after rearrangement and binding to their antigen
introduces point mutations at a high rate
V sequences not C sequences are mutated
B cells mutate in dark zone of a germinal centre

28
Q

advantages of V sequence mutations

A

more diversity
higher affinity

29
Q

because the mutations are random what may happen

A

some BCRs have detrimental
some B cells have favourable mutations

30
Q

BR detrimental mutations

A

less able to bind to the antigen
can recognise self proteins
leads to apoptosis of B cells

31
Q

favourable mutations

A

many Able to bind the foreign antigen- increased affinity
leads to selection of B cells with highest affinity BCRs through interaction of follicular T helper cells, affinity maturation

32
Q

BCR less good at binding antigen

A

doesn’t bind antigen as well as other BCRs
cell doesn’t capture, process and present antigen to T cell
B cel doesn’t receive T cell help and dies

33
Q

BCR better at binding antigen

A

binds antigen better than others
Cell captures, process and presents antigen to the T cell
B cell receives T cell help, proliferates and differentiates to plasma cell

34
Q

what follows somatic hypermutation and selection of high affinity B cell by affinity maturation

A

B cells move further into the light zone
receive a second survival signal from a T helper cell
causes differentiation into either plasma cells or memory B cells
can induce class switching of antibody

35
Q

class switching

A

B cells
make different types or isotopes with different constant regions
each isotope has different characteristics and binds to different Fc receptors on cells

36
Q

what does the variable region do

A

determine antigen specificity

37
Q

what does the constant region do

A

determine antibody class

38
Q

label the antibody

A

top left up to the first dip= variable region
bottom left fro the dip to the bottom= constant region
bottom of two chains= Fc region
blue= heavy chain
orange=light chain
specific hole in the top= FAB region

39
Q

which kinds of antibodies are important in MALT

A

IgA and IgD

40
Q

if barriers are breached what do mucosa have

A

draining lymph nodes
MALTs
perpetually activated innate and adaptive immune cells throughout epithelium and lamina propria

41
Q

what do MALTs do

A

defend body against pathogen entry via mucous membranes
more plasma B cells than in lymph, spleen and. bone marrow

42
Q

2 types of MALT tissue

A

BALTs
GALTS

43
Q

what does BALT stand for

A

bronchus-associated lymphoid tissue

44
Q

what does GALT stand for

A

gut-associated lymphoid tissue

45
Q

GALTs

A

peyers patches in the small intestine
isolated lymphoid follicles
lamina propria immune cells
appendix
palatine tonsils
adenoids
lingual tonsils

all support the mesenteric lymph node

46
Q

where are tonsils found q

A

lingual
palatine
nasopharyngeal

47
Q

tonsils

A

nodular structure with meshwork of reticular cells, macrophages, granulocytes and mast cells
B cells organised into discrete follicles and germinal centres surrounded by cuff of T cells
defends against antigens entering nasal and oral epithelia

48
Q

inductive sites

A

where B and T cells re primed by antigen and differentiate into effector cell

49
Q

effector sites

A

where B and T cells migrate to carry out effector function to clear pathogens

50
Q

Peyers patches

A

inductive sites
30-40 lymphoid nodules
distal small intestine
nodules contain follicles developing into germinal centres on antigen exposure
closely associated with intestinal epithelium

51
Q

microfold cells

A

M cells
occur at inductive sites
have broad process in contact with lumen
deep invagination or pocked in basal membrane
filled with B cells, T cells, dendritic and macrophages

52
Q

antigen in M cells

A

from the lumen of digestive, respiratory or urinary tract is phagocytosed
transported and released into basolateral pocket of cell
antigen taken up by dendritic cells leading to activation or tolerisation of T and B cells in lamina propria

53
Q

examples of immune cells

A

goblet
cytotoxic t cells
plasma

54
Q

goblet cells

A

produce mucu

55
Q

cytotoxic T cells

A

rapidly eliminate infected epithelial cells

56
Q

plasma cells

A

secrete IgA and IgD

57
Q

what is an AMP

A

antimicrobial peptide

Medicine Unit 3 (28 decks)

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