Adaptive Immunity

Question 1

What is the antigen recpotor on T cells?

Answer 1

Antigen Recognition Receptor (TCR)
Alpha and beta chains
Has a CD3 complex to drive activation
Either a CD4 or CD8 accessory moleclue

Question 2

What forms of antigen does the TCR recognise?

Answer 2

Peptides displayed by MHC molecules

Helper T cells (CD4) recognise those via MHC 2
Cytotoxic T cells (CD8) recognise those via MHC 1

Question 3

How are T Lymphocytes activated?

Answer 3

Signal 1- MHC presents peptide to TCR
Signal 2- B7 from APC activates CD28 on T cell
Signal 3- cytokine release determines subtype of Thelper activated

Question 4

Which T helper cells activate cell mediated immunity?

Answer 4

TH1

• needed to aid CD8 differentiate
• intracellular response
• CD4 drives CD8

Question 5

Which type of T helper cell is needed for Humoral immunity?

Answer 5

Th2

• Extracellular microbes
• For B cell production
• CD4

Question 6

What is the antigen regonition of B lymphocytes?

Answer 6

BCR (form of antibody)

Question 7

What forms of antigen can a BCR recognise?

Answer 7

Macromolecules (whole pathogens)
Small chains (eg, polypeptides)

Question 8

How are B cells activated?

Answer 8

Signal 1- 2 crosslinked BCR are activated when pathogen binds (inceases B7 & processes and presents antigen)

Signal 2-TCR engagement (T heper cells binging to B cells via B7 and MHC)

Signal 3- Cytokines

Question 9

Outcomes of B cell activation

Answer 9

Antibody production

Memory B cells

Question 10

What are the different tyoes of antibodies?

Answer 10

IgG- best opsion, present if encountered before, complemt activation, neonatal immunity, toxin neutralisation

IgE- allergies

IgA- mucosal membrabes

IgM- buys us time, first antibody present, complimet activation