L3.4 Adaptive Immunity – T Cells

Question 1

What is the T cell made up of?

Answer 1

Alpha and beta chains, and some have gamma and delta chains, CD3 co receptors are common to all T cells

Question 2

What can T cells respond to?

Answer 2

Can’t respond to antigen alone - it must be presented by MHC

Question 3

How are T cells formed?

Answer 3

• Enzymes cleave DNA
• Make beta chain
• Beta chain tested with surrogate alpha chain (thymus determines whether chain is good enough)
• Alpha chain made

Question 4

What is positive and negative selection?

Answer 4

Positive selection: ensures that thymocytes can recognise and bind to MHC - testing chains
Negative selection: make sure TCR and MHC aren’t binding to tightly that the TCR can’t respond to the antigen

Question 5

What are langerhans cells?

Answer 5

Sit in epidermis and constantly eat things - saves a neutrophil from dying. Move through lymphatics to present info to T cell