Immunology lecture 3

Question 1

Lymphoid organs

Answer 1

• Naive T/B confined
• Io/2o organs
• Functions of 2o lymphoid organs (overcomes unfavourable odds of T/B encountering specific Ag)
• Rapidly screen repertoire + see appropriate clones
• Disadv = time needed to identify + expand relevant clones leaves host vulnerable

Question 2

Acute inflammatory response

Answer 2

• Innate immune system transports Ag from infection to lymphoid to present to T/B cells via inflammatory immune response
• Limits spread of infection
• Infectious microorganism = detected by PRR + NCR
• These receptors = invariant
• Diff TCRs bind diff PAMP
• Inflammation = triggered by damaged cells or basophils → local changes at site of infection (vasodilation, ↑ vascular permeability)

Question 3

Complement system role

Answer 3

• w/o Ig, use alternative pathway
• C5a = chemoattractant, causes secretion of elastase
• Lysis of bacteria
• Opsonisation

Question 4

Microbial killing

Answer 4

• Mø undergoes respiratory burst

- Kills internalised cell by O2-dependent mechanism

Question 5

Dendritic cell

Answer 5

• Immature DCs = acquire Ag by phagocytosis + endocytosis
• In response to inflammation, x phagocytose
• Migrate to lymph nodes, mature (Cd40/86)
• Span adaptive and innate

Question 6

TLR

Answer 6

• Receptors for MAPM
• MAPM include dsRNA, LPS, flagellin
• Bind TLR

Question 7

T-B cell cooperation

Answer 7

• B cells = like APC but use specific Ig
• Th2 activated (MHC on DC) and then migrates to B cell
• Recog. of same peptide-MHC → secretion of cytokine → activate B cell → ↑ secretion of Ig

Question 8

Cost of immune system

Answer 8

• Specific for self + foreign Ag