Mechanisms of immunoregulation suppressor cells

Question 1

What are the 4 main processes involved in immune suppression?

Answer 1

1. Antigen usage
2. Antibody-mediated suppression
3. Hormonal regulation
4. Suppressor T lymphocytes

Question 2

How does antigen usage lead to immune suppression?

Answer 2

1. Antigen on pathogen trigger immune response
2. Immune response reduces antigen concentration
3. Reduced immune stimulation

Question 3

How does antibody-mediated suppression work?

Answer 3

1. Reducing antigen concentration
   -antibody combines with antigen > reducing antigen concentration
2. Immune complexes of antigen & antibody are immunosuppressive
   -antigen & antibodies form immune complexes which are then removed by phagocytes that subsequently release suppressive substances

Question 4

How does hormone regulation lead to immune suppression?

Answer 4

Neuro-endocrine-immunological loop
-effects mediated by soluble messenger proteins

Question 5

How does stress lead to immune suppression?

Answer 5

Stress > pituitary > adrenal cortex > cortisol > immune suppression

Question 6

How does immune suppression caused by stress lead to a fever?

Answer 6

Cytokines released due to immune suppression > hypothalamus changes temperature set point = fever

Question 7

What are the 2 main types of suppressor cells?

Answer 7

CD4+ T(reg) cells - spontaneously arising/induced types
(majority)
CD8+T(reg) cells - induced type
(less important)

Question 8

How do CD4+ suppressor T cells work?

Answer 8

Regulate the balance of Th1 vs Th2
Natural suppressors (CD4+, CD25+ T reg)
Induced suppressors (CD4+ IL-10 producing Tr1 cells)
Th3 TGF𝛃 producing induced suppressors

Question 9

How can one CD4 T cell subset suppress another, in terms of immune deviation?

Answer 9

-Th1 cells produce IFN𝛄 & promote CMI (cell mediated immunity)
-Th2 cells produce IL4 & IL13 > promote humoral (antibody) immunity
-In an immune response, one may dominate over the other, resulting in a polarised immune response = “immune deviation”

Question 10

How do CD4+, CD25+, FoxP3+ T reg act as natural suppressors?

Answer 10

Always normally present in body
Require direct contact to work
Control of unwanted immune responses (eg autoimmunity)
Can be identified by the fact that they express CD25 & FoxP3
Are found in humans & animals (eg dogs, cats, horses)

Question 11

How does IL-10 produce Tr1 induced suppressors?

Answer 11

Induced by an immune response
Called Tr1 cells
Work via cytokines (not direct contact) - key cytokine is IL-10