Lecture 14 Exam 3

Front 1

Know the three major MALT tissues and four major GALT tissues

Back 1

Malt = Gastrointestinal tract, respiratory tract, and urogenital tract

Galt = Mouth, Stomach, Lg Intestine, and Sm Intestine.

Front 2

Name the four ways our normal flora is essential to gut function

Back 2

1. synthesize nutrients

2. breaking down ingested plants

3. crowing out pathogens

4. development of gut lymphoid tissue

Front 3

Describe differences between systemic and mucosal immunity

Back 3

Systemic immunity: Occasional interaction with microbes

Reactive response - make effectors after infection

Effectors only recruited to tissue during, removed afterward

Stimulates inflammation

Front 4

Describe differences between systemic and mucosal immunity

Back 4

Mucosal Immunity : close and continuous contact with microbes (all potential pathogens)

Proactive response - makes effectors continuously

Effectors regularly populate tissue

Suppresses Inflammation

Front 5

Describe the acquisition of antigen by M-cells and DCs

Back 5

M cell receptors bind and endocytose pathogens which are transported to the lumen by transcytosis

DCs reside in the lamina proporia, but can extended a process between enterocytes to obtain Ag from the lumen without disturbing barrier

Front 6

Describe the GALT effector cells including IELs

Back 6

Gut epithelium includes intermittent intraepithelial lymphocytes (IELs = CD 8 T cell)

Gut epithelium and lamina propria beneath are populated with effector cells: activated CD4 & CD 8 T cells and plasma cells.

Front 7

Describe what Ab dominate in the GALT and what they do

Back 7

Ab binds to mucins on epithelial cell surfaces and neutralize passing pathogens, commensals, and food antigens to prevent colonization

Front 8

Know the purposes of the GALT

Back 8

Galt undergoes chronic immune response (M cells and DCs sampling lumen)

Macrophages do not produce inflammatory cytokines & decreased TH1 response

GALT purpose is not to remove microbes, but to restrict them to the lumen

"Germ- Free" mice developed weakened immune systems - smaller secondary lymphoid tissues, lower levels of Ig, and reduced capacity to mount and immune response.

Front 9

Describe the steps in the path of lymphocytes through GALT (also in summary pic)

Back 9

1. Naive B & T cells from bone marrow & thymus go to blood stream and circulate through all of the secondary lymphoid tissues

2. Naive lymphocyte homing to the peyers patches and mesenteric lymph nodes

3.No bind Ag = leave via efferent lymph

4. Yes bind Ag = activation, proliferation, differentiation

5. Activated lymphocytes enter circulation via efferent lymph.

6. Lymphocytes activated in the MALT will ONLY re-enter MALT.

7. MALT specific homing into lamina propria

Front 10

Explain homing to MALT and how it differs from general lymphocyte homing to lymph nodes

Back 10

-DC presents Ag to naive T cell & converts retinol to retinoic acid (RA)

-RA mediates up-regulation of INtegrin alpha4:Beta7 and CCR9

-IL-5 & 6 mediate CSR of B cell to produce IgA

- These activated lymphocytes will now home to Galt

Front 11

Describe why MALT activated lymphocytes only return to MALT from circulation

Back 11

Activation in the MALT causes

-Down regulation of CCR7

-Up-regulate CCR9 & Integrin alpha4 :Beta 7

Malt - specific homing : Alpha 4 :Beta 7 binds MAd-CAM-1 ^ CCR9 binds CCL25

Front 12

Explain the 5 functions of dimeric IgA in the GALT

Back 12

1. Export from Lamina Propria

2. Neutralization in Cell

3. Neutralization in Lumen

4. Deliver native Ag

5. Deliver digested Ag

Front 13

What is selective IgA deficiency and what might cause it

Back 13

Patients with IgA deficiency have no IgA, but higher levels of IgM, IgG, and IgD

Speculation says it could either be due to a compensation based on missing IgA or the fact the the body has to produce a set amount of antibodies regardless of type

Front 14

Describe the function of NOD

Back 14

NOD 1 - recognizes G - bacteria

NOD 2 - recognizes G + bacteria

binding of ligand to NOD activates NFkB pathway

Production of cytokines, chemokines, and defensins

Front 15

Explain what defense against intestinal helminthes is most effective & the mechanism by which that occurs

Back 15

Our bodies counter these infections by forcefully expelling the worms out of the gut lumen and expelling them in feces (through the TH2 response) most effective at clearing an intestinal helminth infection

TH1 response generates inflammation and exacerbates the infection

Front 16

Define: MALT,

Back 16

Mucosal associated lymphoid tissue - aggregates of lymphocytes, mucosal epthelia and lamina propria of the GI, respiratory & urogenital tracts, INcludes GALT (gut) & Balt (bronchial)

Front 17

Peyer’s Patch,

Back 17

Organized GALT in the wall of the small intestine

Front 18

Mesenteric Lymph Node,

Back 18

Lymph node local to the MALT, naive lymphocytes enter & are activated & travel to lamina propria

Front 19

Mucosal Epithelium,

Back 19

Mucus secreting epithelium lining the MALT

Front 20

Intestinal Lumen,

Back 20

Channel within sm INtestine where food and microbes are present

Front 21

Lamina Propria,

Back 21

Area of connective tissue and activated immune cells below mucosal surface.