Mucosal immunity

Question 1

what are primary lymphoid organs

Answer 1

sites where b and T cells are made and matured

Question 2

where are the primary lymphoid organs

Answer 2

bone marrow
thymus

Question 3

what are the secondary lymphoid organs

Answer 3

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

Question 4

where are the secondary lymphoid organs

Answer 4

lymph nodes
spleen
mucosa associated lymphoid tissues/MALTs

Question 5

capsulated lymphoid tissues

Answer 5

lymph nodes
spleen

Question 6

non-capsulated lymphoid organs

Answer 6

mucosa associated lymphoid tissues
50% of bodies lymphoid tissue

Question 7

what are capsulated lymphoid tissues designed for

Answer 7

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

Question 8

function of the spleen

Answer 8

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

Question 9

how do antigens and lymphocytes enter the spleen

Answer 9

via the splenic artery

Question 10

2 distinct regions of the spleen

Answer 10

white pulp
red pulp
separated by a diffuse marginal zone

Question 11

differences between lymph nodes and spleen

Answer 11

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

Question 12

red pulp function

Answer 12

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

Question 13

white pulp function

Answer 13

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

Question 14

marginal zone function

Answer 14

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

Question 15

process of immune response in the spleen

Answer 15

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

Question 16

lymph nodes

Answer 16

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

Question 17

lymph nodes and immune response

Answer 17

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

Question 18

fluid in the efferent lymphatic vessel

Answer 18

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

Question 19

production of secondary follicle in lymph node

Answer 19

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

Question 20

what are lymphoid follicles

Answer 20

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

Question 21

primary follicles

Answer 21

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

Question 22

what occurs when germinal centres are formed

Answer 22

the follicle is called a secondary follicle

Question 23

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

Answer 23

proliferate forming germinal centres

Question 24

germinal centres

Answer 24

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

Question 25

what is occurring in the dark zone

Answer 25

cell proliferation

Question 26

what is occurring in the light zone

Answer 26

cell death

Question 27

somatic hypermutation

Answer 27

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

Question 28

advantages of V sequence mutations

Answer 28

more diversity higher affinity

Question 29

because the mutations are random what may happen

Answer 29

some BCRs have detrimental some B cells have favourable mutations

Question 30

BR detrimental mutations

Answer 30

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

Question 31

favourable mutations

Answer 31

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

Question 32

BCR less good at binding antigen

Answer 32

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

Question 33

BCR better at binding antigen

Answer 33

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

Question 34

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

Answer 34

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

Question 35

class switching

Answer 35

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

Question 36

what does the variable region do

Answer 36

determine antigen specificity

Question 37

what does the constant region do

Answer 37

determine antibody class

Question 38

label the antibody

Answer 38

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

Question 39

which kinds of antibodies are important in MALT

Answer 39

IgA and IgD

Question 40

if barriers are breached what do mucosa have

Answer 40

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

Question 41

what do MALTs do

Answer 41

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

Question 42

2 types of MALT tissue

Answer 42

BALTs GALTS

Question 43

what does BALT stand for

Answer 43

bronchus-associated lymphoid tissue

Question 44

what does GALT stand for

Answer 44

gut-associated lymphoid tissue

Question 45

GALTs

Answer 45

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

Question 46

where are tonsils found q

Answer 46

lingual palatine nasopharyngeal

Question 47

tonsils

Answer 47

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

Question 48

inductive sites

Answer 48

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

Question 49

effector sites

Answer 49

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

Question 50

Peyers patches

Answer 50

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

Question 51

microfold cells

Answer 51

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

Question 52

antigen in M cells

Answer 52

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

Question 53

examples of immune cells

Answer 53

goblet cytotoxic t cells plasma

Question 54

goblet cells

Answer 54

produce mucu

Question 55

cytotoxic T cells

Answer 55

rapidly eliminate infected epithelial cells

Question 56

plasma cells

Answer 56

secrete IgA and IgD

Question 57

what is an AMP

Answer 57

antimicrobial peptide