A1. imm

Question 1

What are the determining factors in an immune response?

Answer 1

1. Nature of the Ag
2. Maturity of the immune system
3. Route of Ag administration
   - IV, Orally, Intranasally, intramuscularly, intraperitoneally etc.
4. Dose, persistence & removal of Ag

Question 2

Describe the strength of the immune response towards pathogens

Answer 2

Response can be weak or strong

Question 3

What type of Ag will lymphocytes not respond to

Answer 3

Self antigens

Question 4

Define tolerance

Describe features of tolerance

What does it differ from

Answer 4

Specific immunological non-reactivity of an Ag
(tolerance to self Ag & non-self)

Tolerance is an active immune response. It is Ag specific & has immune memory

Differs from non-specific immuno-suppression & immunodeficiency

Question 5

Name 1y & 2y lymphoid organs

what are they essential for

Answer 5

1y -Bone marrow & thymus
2y - lymph nodes, spleen, lymphatic vessels

Essential to maintain healthy immune response

Question 6

How does the immune system distinguish self and non self

define: central tolerance

Answer 6

Via central & peripheral tolerance

1. CT is a control (checkpoint) for immune development (of B & Tc)
   - Non-self reactive Tc development in thymus
   Non-self reactive Bc development in the bone marrow
2. The control of immune responses in peripheral (2y) lymphoid organs

Question 7

Name mechanism & site of action:

1. Central tolerance
2. Ag segregation
3. Peripheral anergy

Answer 7

1. M: Deletion, editing
   S: Thymus, BM
2. M: Physical barrier to self-Ag access to lymphoid system
   S: Peripheral organs (e.g. thyroid pancreas)
3. M: Cellular inactivation by weak signalling w/out co-stimulus
   S: Secondary lymphoid tissue

Question 8

Name mechanism & site of action:

1. Regulatory cells
2. Cytokine deviation
3. Clonal deletion

Answer 8

1. M: Suppression by cytokines, Intracellular signals
   S: Secondary lymphoid tissue & sites of inflammation
2. M: Differentiation of Th2 cells, limiting inflammatory cytokine secretion
   S: Secondary lymphoid tissue & sites of inflammation
3. M: Apoptosis post-activation
   S: Secondary lymphoid tissue & sites of inflammation

Question 9

1. Why is Tc development impt
2. Define: Positive selection
3. Define: Negative selection
4. where does +ve & -ve selection take place
   Why is it required

Answer 9

1. Imp as functional immune system requires a selection of T lymphocytes expressing receptors that are MHC restricted by tolerance to self antigen.
2. +ve selection: the process, focusing on Tc receptor to recognize the peptides are bound to self MHC molecules
3. -ve selection: the process that Tc react strongly with self antigens are removed.
4. Thymus, mature & exit into the periphery
   Needed for Tc development otherwise they die through neglect

Question 10

What is the role of AIRE

AIRE promotes expression of what

Answer 10

AIRE: autoimmune regulator
Is the gene which controls expression of the immature (self-protein) Tc (released by thymic epithelial cells) in thymic medulla

Stops immature Tc responding to self

AIRE expressed in the medulla (thymus) promotes the expression of proteins expressed in the peripheral tissue