Lecture 27 Immunopathology

Question 1

Microbial evasion strategies

Answer 1

• Protein A in Stap. aureus can shut down complement system by inhibiting opsonization.
• inhibit chemotaxis
• kill pahgcyte
• inhibit phagocytosis: S. pneumoniae; Capsule
• inhibit phagolysosomal fusion: M. TN
• resist antibacterial lysosomal action and multiply w/in cell: M. leprae, Salmonell sp., S. aureus.

Question 2

Exotoxins as super antigens

Answer 2

• proteins prodced by Gram +ve or -ve bacteria including cytolytic enzymes and receptor-binding proteins that alter a function or kill the cell.
• concurrently binds TCR and MHC II molecule on another cell w/o requiring Ag.
• non-specific means of activating T cells can trigger life-threatening autoimmune-like response via IL-1 and IL-2.
• Superantigens include toxic shock syndrome toxin or S. aureus, staphylococcal enterotoxins, and the erythrogenic toxin A or C of S. pyogenes.

Question 3

Acute phase proteins: CRP

Answer 3

• Macrophage, endothelial cells, T-cells produce IL-6, which stimulate CRP production by liver.
• CRP blood test
  
  • Low risk<1 mg/L
  • High risk>3 mg/L
• CRP-R on macrophage
• Stop smoking decrease CRP levels
  
  • exercise, lose wt, etc…
• metabolic syndrome

Question 4

Acute-phase response to cell wall components example

Answer 4

• M protein of S. pyogenes anti-genically mimics heart tissu-> anti-M protein Ab cross-react w heart muscle to cause damage
  
  • rheumatic fever
  • immune complex deposited in glomeruli of kidney
• Chlamydia, Treponema (syphilis), Borrelia (Lyme disease), and other bacteria the host immune response is an important cause of disease sx in patients.

Question 5

Coombs classification

Answer 5

• review your immuno notes

Question 6

Autoimmune disease & MHC Ag

Answer 6

• people w certain MHC Ag are at high risk for autoimmune responses (ex. HLA-B27: human leukocyte ag, juvenile rheumatoid arthritis, ankylosing spondylitis)
  
  • responses are associated w inflammatory TH1 response.
  • MS may be triggered by viruses such as HHV-6 or measles.

Question 7

Hereditary angioneurotic edema

Answer 7

• genetic form of angioedema aka Quinke’s disease
• Persons w it are born lacking C1 esterase inhibitor
• Non-pitting edema

Question 8

Pediatric Autoimmune Neuropsych disorders (PANDA)

Answer 8

• associated w streptococcal infections
• resulting in OCD and Tourette’s syndrome
• sx worsen following strep. infections such as strep throat and Scarlet fever
• mechanism present: Syndenham’s Chorea or St. Vitus dance