Mucosal Immunity

Question 1

mucosal surface

Answer 1

line the body cavaties
line internal organs
majority of infectious agents invade through this route
permeable for gas exchange/food absorption

Question 2

mucosal epithelium

Answer 2

only barrier between invasion of tissues and the commonsal bacteria
epithelial cells form monolayer barrier - tight functions

Question 3

MALT

Answer 3

Mucosal Associated Lymphoid Tissue

lymphoid tissue in the musosa
has peyers patches where local B and T cells reside
peyers patches have specialised M cells for endocytosis and phagocytosis

Question 4

Stem cells differentiate into different cell types

Answer 4

enterocytes - absorption of food
paneth cells - antimicrobial peptide production
goblet cells - mucous secretion

Question 5

Antimicrobial peptides

Answer 5

a defensins - membrane dysfunction
lactoferrin
RNAses
lysozyme 
cathelecidin 
lectins

Question 6

immunoglobin A

Answer 6

major antibody of mucous
no inflammation - no initiation of complement
protease resistant
epithelial cells Fc receptors bind and take them up into the lumen of the gut

Question 7

intraepithelial lymphocytes (IELs)

Answer 7

type a = CD8 cell
kill infected cells, recognise MHC1+peptide
release granzyme
type b = NK cell
triggered by stress signals MICa and Micb recognised by NKG20

Question 8

innate lymphoid cells

Answer 8

detect environmental changes by sensing and secreting cytokines
ILC1 = Th1
ILC2 = Th2
ILC3 = Th17

Question 9

ILC1

Answer 9

TBET transcription factor activated by IL-12

secrete IFN-y

Question 10

ILC2

Answer 10

GATA transcription factor activated by IL10
secrete IL-5 and Il-9
lead to antibody production, eisonophil activation = helminth

Question 11

ILC3

Answer 11

respond to IL23 ROryt transcription factor

neutrophil activation - Il-17

Question 12

M cells

Answer 12

special dendrite like cells sample environment

Question 13

tregs

Answer 13

anti inflammatory

Question 14

homing of B and T cells

Answer 14

sample luminal contents

homed back to musocal surfaces via madCAM receptors on mucosal bind retinoic acid

Question 15

aberrant mucosal immunity

Answer 15

chrons - NOD2 mutation, activation or PRR, NFkB signalling - inflammation
coeliac - HLA-DQ2 binds gliadin on gluten - inflammation

Question 16

Shigella

Answer 16

penetrates gut epithelium by invading M cells
cell wall peptides bind NOD1 receptors and activate NFKb pathway, Epithelium secrete CXCLB to recruit neutrophils, inflammation
shiga toxin inhibits translation - stops protein synthesis and causes cell death
uses type 3 secretion system

Question 17

clostridium difficile

Answer 17

shows importance of human commensal in protecting against disease
broad strain antibiotics wipe out resident and allow clostridium to colonise,
Secretes toxin A which inactivates GTPases, changes in cell morphology and damage to tight junctions