Lymphocytes

Question 1

What is adaptive immunity?

Answer 1

memory against recurring infection

Question 2

What is an epitope?

Answer 2

regions of antigen where receptor will bind to

Question 3

How do T cells recognise antigens?

Answer 3

T cells recognise primary sequence structure of MHCs (proteins)

Question 4

How do B cells recognise antigens?

Answer 4

B cells recognise 3D structure - how protein folds in place

Question 5

How do lymphocytes deal with antigen diversity?

Answer 5

All combinations of receptors are made.

Enforce ma

Question 6

A BCR on a B cell is the same as the antibody it produces. Why is an antibody unique?

Answer 6

BCR gives unique mRNA. Therefore unique antibody

Light gene and heavy gene combine. The genes loop. V and J.

Question 7

What is IMMUNOGLOBULIN GENE REARRANGMENT

Answer 7

Each BCR (antigen specific receptor) encoded by separate multigene families.
During B cell maturation, gene segments rearranged and brought together

Question 8

What are 2 types of T cells?

Answer 8

• CD8+ (cytotoxic, kill pathogens)

- CD4+ (normal, clones)

Question 9

How do TCR (T cell receptors) work?

Answer 9

• recognises linear antigen fragments
• receptor cell clustering
• Once it sees antigen, intracellular cell signalling.

Question 10

What do MHC do?

Answer 10

Define self and non self cells

Question 11

What is MHC coded by?

Answer 11

HLA genes

Question 12

MHC is polygenic. What does this mean?

Answer 12

It encodes several different versions of the same things

Question 13

MHC expression is co dominant. What does this mean?

Answer 13

maternal and paternal genes both expressed

Question 14

How many classes of MHC are there?

Answer 14

MHC class 1 (INTRACELLULAR MATERIAL)
MHC class 2 (EXTRACELLUALR)

Question 15

How does class 1 MHC work?

Answer 15

• class 1 presented on all uncleared cells.
• They present proteins made in cell on cell surface, so body recognises as self.
• Talk to CD8 Viral proteins on MHC show foreign.

Question 16

how does class 2 MHC work?

Answer 16

• on antigen presented cells.
• Dendritic look for infectious material.
• Present on MHC.
• Talk to CD4.

Question 17

How do CD8 work?

Answer 17

• kill cells by apoptosis
• Fragmentation of nuclear DNA
• CTL store performing, granzymes, granulysin in cytotoxic granules
• Perforin molecules polymerise, form pores

Question 18

How does cd4 work?

Answer 18

Produces cytokines

Question 19

Why do B cells need help from T cells when making antibodies?

Answer 19

They only recognise soluble antigens, and have no MHC

Question 20

What is the variable region in antibodies for?

Answer 20

Specifity

Question 21

What is the constant region in antibodies for?

Answer 21

Functionality

Question 22

Name 3 roles of antibodies:

Answer 22

• neutralisation (binding to virus)
• Opsonisation (promotes phagocytosis)
• Complement activation (enzyme cascade reactions leading to bacterial cell death)

Question 23

What sends naive B cells an accessory signal? (Apart from antigens)

Answer 23

• from microbial constituents ( T independent, only form IgM.) These molecules cluster BCR together, starts signalling cascade. No memory
• T cell helper. All iG classes and memory.

Question 24

Roughly, how is a B cell activated by a T cell?

Answer 24

• BCR recognises antigen
• B cell engulfs antigen
• Presents on MHC2
• T CD4 cell that recognised same antigen on DENDRITIC recognises B cell
• B cell activated