L3 - Cells and Tissues of the Immune System II

Question 1

What are the 4 fundamental principles of the immune system

Answer 1

1) Recognition - must recognize what you want to keep out
2) Effectors - dirty work to get rid of the invader
3) Regulation - doesn’t matter if you have a fast car if you can’t brake
4) Memory - Stronger after the first encounter

Question 2

What does the immune system need to be about to discern between?

Answer 2

1) Nonself vs Self

2) Microflora vs pathogens

Question 3

How do immune systems not destroy microflora?

Answer 3

• Become conditioned to the signals commensal bacteria give (creates a context)
• You are not tolerant to commensal bacteria, you just accept them

Question 4

How does pathogen recognition occur via PRRs?

Answer 4

Patterns - conserved structures required for survival
Location - cytosolic DNA sensors
Quantitiy - Even free self DNA can be a problem if its too much quantity
Threshold - Accumulation of signals

Question 5

What are some immune effector mechanisms?

Answer 5

• Phagocytosis
• Microbicidal Agents
• Complement

Question 6

Describe bridging of the innate system through dendritic cells

Answer 6

• Immune dendritic cells residing in peripheral tissues collect antigen
• Migrate to lymphatic vessels to regional lymph nodes
  Present antigen to naive T-cells to activate them

Question 7

Describe the difference between immature and mature dendritic cells

Answer 7

Immature Dendritic Cells:

• Higher expression of Fc and mannose receptors
• Low expression of molecules involved in T cell activation (B7, ICAM-1, IL-12)
• Lower half-life for MHC II molecules and lower number of surface MHC II molecules

Question 8

What do cytotoxic T cells do?

Answer 8

Kill virus-infected or tumour-transformed cells with very high degree of specificity

Question 9

What do helper T cells do?

Answer 9

• Produce cytokines
• Activate anti-microbial defense mechanism
• Assist in antibody production

Question 10

How and why are immune systems regulated/curtailed?

Answer 10

• Disrupts lymphocyte homeostatsis otherwise

Regulates via inhibitory cytokines (IL-10, TGF-b), regulatory helper T cells

Question 11

What are the three different memory T cells and where do they reside?

Answer 11

• Central: secondary lymphoid organ and blood
• Effector: Secondary lymphoid organ, blood and non lymphoid organ
• Tissue resident: Non lymphoid organ