GI Immunology

Question 1

what are the lymph nodes in the gut called?

Answer 1

mesenteric lymph nodes (there are lots of them present in the gut)

Question 2

where are the 3 major places for immune cell in the intestine?

Answer 2

Gut associated lymphoid tissue:

• Peyer’s patched (containing mostly naive cells)
• smaller lymphoid follicles
• lamina propria (contains mostly effector/activated cells)

Question 3

what 2 cell types cover the Peyer’s patch?

Answer 3

epithelial cells

M cells

Question 4

what do the M cells of the Peyer’s patches do?

Answer 4

they take part in antigen sampling of the gut

Question 5

the m cells transport the antigen from the lumen into the ____ ____ where the ____ cell engulfs it in order to present the antigen to the lymphocytes

Answer 5

peyer’s patch

dendritic

Question 6

what produces IgA?

Answer 6

plasma cells (activated B cells)

Question 7

where do the activated lymphocytes from the Peyer’s patches and mesenteric lymph nodes end up and why?

Answer 7

lamina propria

the end up here due to the homing receptors they express

Question 8

the lamina propria contains what kind of cells? (3)

Answer 8

active immune cells/effector cells:

• T cells
• plasma cells secreting IgA

Question 9

what 2 cells are present in the intraepithelial layer of the lamina propria?

Answer 9

CD8 (T killer cells) also called intraepithelial lymphocytes (IELs)
dendritic cells

Question 10

what is the most important immunoglobulin in mucosal immunity?

Answer 10

IgA

Question 11

how does IgA prevent infection? (2)

Answer 11

neutralisation of antigens/pathogens (in gut lumen and within cells)
they can transport antigens/pathogens found in the lamina propria into the lumen to be secreted out as faeces

Question 12

what is CVID?

Answer 12

Common variable immunodeficiency

Recurrent sinopulmonary and GI infections
Low IgG, IgA, IgM, IgE
Defective antigen specific antibody response

Question 13

what is XLA?

Answer 13

X-linked agammaglobulinemia

B cells can’t develop resulting in agammaglobulinemia

Question 14

what is CGD?

Answer 14

Chronic granulomatous disease

Increases the body’s susceptibility to infections by certain bacteria or fungi

The invader that has been phagocytosed cannot be cleared creating a granuloma

Question 15

what is SCID?

Answer 15

Severe combined immunodeficiency

Defects in T and B cells
Overwhelming opportunistic infections