Adaptive immunity

Question 1

MHC I

Answer 1

• 3 alpha groups and 1 beta group
• on all nucleated cells + platelets
• displays endogenic protein fragments
• bound by CD8 molecules on T cytotoxic cells

Question 2

MHC II structure

Answer 2

• 2 alpha groups and 2 beta groups
• on B cells, macrophages, monocytes, APCs, some T helpers
• bound by CD4 molecules on T helpers
• displays antigens from extracellular proteins from phagocytosis

Question 3

B cell antigen receptors

Answer 3

same shape as antibodies they produce

Question 4

B cell genesis

Answer 4

Bone Marrow
- Pro-B cell: heavy chain VDJ rearrangement
- Pre-B cell: light chain VDJ rearrangement
- immature B cell
spleen or lymph node
- mature B cell

Question 5

B-cell activation: B-cell receptor

Answer 5

antigen receptor recognises antigen present then second receptor signals that foreign antibody detected

Question 6

B-cell activation: germinal centre response

Answer 6

• T helper cells activate B cells -> clonal expansion into centroblasts -> some convert into short lived plasma cells which produce IgM then undergo apoptosis
• affinity selection (B cells that produce antibodies with higher affinity to specific antigen are chosen) - T helper cells activate them into long-lived plasma cells which produce IgG,A,E or B memory cells
• somatic hypermutation: mutations introduced into centroblasts by enzyme AID causing small changes to antibodies
• class-switch recombination: antibodies change type

Question 7

what do Th2 cells recognise

Answer 7

B-cells presenting antigens on MHC II

Question 8

VDJ recombination

Answer 8

• takes place during B cell development
• allows diversity in receptors

Question 9

IgM

Answer 9

• first Ig response made w/o T cells
• most effective at activating complement pathway
  2 forms
• pentameter
• B-cell receptor

Question 10

IgG

Answer 10

• most abundant
• opsonin
• activates classical complement pathway
• kills virus infected cells alongside NK cells
• only Ig that can cross placenta

Question 11

IgE

Answer 11

• allergic reactions and anti-parasitic responses
• binds to receptors on mast cells, basophils, and eosinophils -> cytotoxic granule release
• sometimes produced for non pathogenic targets :(

Question 12

IgA

Answer 12

2 forms: IgA1+2
- opsonin for eosinophils, neutrophils, and macrophages
- main Ig in mucosal membrane
- babies recieve through breast milk -> neutralises pathogens in GI tract

Question 13

IgD

Answer 13

• found on mature B-cells
• signal that B-lymphocytes are ready to leave bone marrow

Question 14

T-helper cell activation

Answer 14

• MHC II on APC presents antigen fragment to variable region of T cell receptor
• T cell produces cytokines

Question 15

T cytotoxic (CD8) activation

Answer 15

• MHC I presents foreign antigen fragment to receptor
• CD8 release perforin and granzymes

Question 16

T helper 1

Answer 16

produce interferon gamma and activate/ increase response of macrophages

Question 17

T helper 2

Answer 17

produce IL4+5 and activate/ increase response of B cells, mast cells, eosinophils

Question 18

tolerance

Answer 18

specific immune non-reactivity against certain antigens

Question 19

anergy

Answer 19

immune system can’t do normal immune response against specific antigen