Mucosal Immunity

Question 1

Innate immunity

Answer 1

1=Goblet cells secrete mucus that act as a barrier and have antibacterial function

2) Epithelium: barrier and antibacterial
3) Paneth cells: antibacterial (defensins) secreting cells
4) m cells: antigen sampling, bring antigens into Peyer’s patches

Question 2

epithelial host defense

Answer 2

have TLRs and NLRs located inside the cell and in the BL surface/ lamina propria to avoid reaction to normal flora

Functionally tend to be anti-inflammatory

if bacteria INVADES INTO THE CELL then they activate TLRs or NLRs

Question 3

M cells

Answer 3

Pinocytose material and transport pathogens to Peyer’s patches (NOT APCs)
lack microvilli
located at the top of the dome

Question 4

CD 11b+
CX3CR1+
DENDRITIC CELL

Answer 4

sample antigens either in the lumen using its arm
activate T cells with IL6, and TGF-B
T cells then Produce IL17(induces gut tolerance) and IFN-g

Question 5

CD103+
CX3CR-
dendritic cell

Answer 5

Sample antigen in the ICF

can induce Foxp3+ Treg cells which dampen the immune response using RA

Question 6

IgA function

Answer 6

neutralize biologically active viruses, toxins and enzymes, sequesters antigen
secreted into the gut lumen
*inhibits bacterial adherence to epithelial surface to prevent them from entering
**does not induce complement=NON-INFLAMMATORY

Question 7

immunological abnormalities in IBD

Answer 7

1) Mounting an abnormal immune response against the gut flora (due to defective defensins)
2) increased inflammation (high Th17 and Th1 cells)
3) defective Treg function (lack of FoxP3, IL2/R)

Question 8

Celiac disease

Answer 8

immune mediated disease mediated by T cells
deamidated gluten peptide are presented to T cells, which become pathogenic

antibodies against gluten and transglutaminase, but they are not thought to be pathogenic

T cells attack the vili causing villus atrophy

Question 9

IgE mediated allergy

Answer 9

food specific igE
acute or chronic cutaneous sx or anaphalaxis

most common in young children

Question 10

Defensins

Answer 10

small peptides that contain disulfide bonds
anti-microbial properties and can activate other immune cells

alpha produced by paneth cells and neutrophils in the SI

beta is produced in the colon

Question 11

Lymphocyte homing to lamina propria

Answer 11

activation of T or B cell by DC in peyers patch or lymph node induced integrin a4B7 expression using RA.
Integrins binds to MadCaM on lamina propria venule while CCR9 (SI) or CCR10 (Colon) bind chemokines

tend to be Tregs or IgA secreting B cells

Question 12

Class switching to IgA

Answer 12

occurs in the presence of activated T cells and NO with TGFB

Or….DC can directly induce class switch to IgA using TGF-B and APRIL

Question 13

Th17

Answer 13

may play a role in colonization and protection of the gut

produce IL17 and IL22

overactive Th17 may cause Crohn’s

Question 14

Th2

Answer 14

protect against helminthic infections

IL4 and IL13, but may be indicated in food allergy due to activation of Mast Cells

Question 15

FoxP3+ Tregs

Answer 15

highly concentrated in the lamina propria of the gut

induced by CD103 DC, RA, and TGF-B

produce TGFB, IL10, IL2

**deficiencies may lead to IBD

Question 16

Non-IgE mediated

Answer 16

Th2 mediated
chronic and/or GI sx
eosinophilic disorder