7-Development of T lymphocytes

Question 1

Where do T cells develop?

Answer 1

Originate in bone marrow but mature in thymus

Question 2

What happens in DiGeorges syndrome?

Answer 2

The thymus fails to develop –> no T cell production.

Question 3

What are thymocytes?

Answer 3

Cells that are commited to the T cell lineage

Question 4

What important parts of mature T cells do thymocytes DO NOT express?

Answer 4

CD or CD8 or TCR

Question 5

Which loci compete with β locus to make TCR’s?

Answer 5

γ and δ loci

Question 6

How does commit to being a γδ T cell?

Answer 6

By making functional γδ receptor before a function β chain

Question 7

What happens if a functional β is made before γδ receptor?

Answer 7

It’s incorporated into a protein called the pre-TCR and favors the αβ lineage

Question 8

What happens at the double positive thymocyte stage?

Answer 8

The αβ lineage is favored, gene rearrangement stops, and proliferation and CD4 and CD8 are expressed.

Question 9

If a double positive thymocyte makes an αβ receptor before an γδ receptor, what will that lineage be?

Answer 9

αβ lineage

Question 10

Where are double + thymocytes found?

Answer 10

Thymic cortex

Question 11

What type of markers does the early pro T cell have?

Answer 11

Nothing really- doesnt have TCR, CD8 or CD4

Question 12

What type of markers does the late pro T cell have?

Answer 12

TCR but no CD4/8

Question 13

What type of markers does the pre T cell have?

Answer 13

TCR, pre-Talpha, CD4 & CD8

Question 14

What type of markers does a single + T cell have?

Answer 14

TCR and either CD4 or CD8

Question 15

What are the 2 outcomes of + selection in the thymus?

Answer 15

1. the T cell is able to interact with the body’s MHC molecules, and 2. it detemines whether the T cell will be CD4 or CD8

Question 16

What is missing in bare lymphocyte syndrome?

Answer 16

either MHC-I or MHC-II. awwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww crap!

Question 17

What is negative selection?

Answer 17

It’s when T cells are deleted when they bind too strongly to self peptide:MHC complexes

Question 18

Why is negative selection good?

Answer 18

Cuz otherwise we would get autoimmune reactions

Question 19

How does AIRE drive negative selection?

Answer 19

It controls the mechanism that prevents the immune system from attacking the body (prevents autoimmune disorders)

Question 20

What would happen if someone was defective in AIRE?

Answer 20

They would have broad-spectrum autoimmune diseases known as APECED

Question 21

What are the functions of Tregs?

Answer 21

They are CD4 T regulatory cells that supress the immune system to prevent excessive reactions to infections.

Question 22

How do naive T cell get turned into activated T cells?

Answer 22

Encounter with their specific Ag