Chapter 10 Study Guide

Question 1

type I hypersensitivity

Answer 1

type I = immediate hypersensitivity

• antibody = Ig E
• antigen = soluble antigen
• pathogenesis
  1. first exposure = allergen enters the body and Ig E is made in response → Ig E binds to mast cells via Fc receptor
  2. second exposure = allergen binds to Ig E → cross linking of Ig E → degranulation = mast cells release histamine and leukotriene → inflammatory response
• examples = local and systemic anaphylaxis, seasonal hay fever, food allergies, drug allergies, urticaria

Question 2

type II hypersensitivity

Answer 2

type II hypersensitivity = cytotoxic reaction → tissue specific → creates MAC = membrane attack complex

• antibody = Ig G or Ig M
• antigen = cell bound
• pathogenesis
  1. Ig G or Ig M binds to cell bound antigen → complement activation and cell lysis
  2. Ig G mediates ADCC
• examples = mismatched blood type transfusion, hemolytic disease of newborn → RBCs are lysed

Question 3

type III hypersensitivity

Answer 3

type III hypersensitivity = immune complex reactions → not tissue specific

• antibody = Ig G and Ig M
• antigen = soluble
• pathogenesis
  1. antigen-antibody complexes (immune complexes) are deposited in tissues
  2. complement activation attracts inflammatory mediators and recruits neutrophils
  3. neutrophils release enzymes → damage tissues
• examples = systemic lupus erythematosus = SLE, post-strep glomerulonephritis, rheumatoid arthritis, PSGN

Question 4

type IV hypersensitivity

Answer 4

type IV hypersensitivity = delayed cell-mediated reaction

• immune reactant = T cells
• antigen = soluble or cell bound
• pathogenesis = TH1 cells secrete cytokines → activate macrophages and cytotoxic T cells → initiates tissue damage
• examples = contact dermatitis, type 1 diabetes mellitus, multiple sclerosis = MS, tuberculin skin test

Question 5

autoimmunity etiology

Answer 5

abnormal excessive immune responses toward own tissues

autoimmunity is basically a failure of self-tolerance → immune system attacks its own tissues

Question 6

what increases risk of autoimmune disorders?

Answer 6

• MHC genes (HLA)
• females

Question 7

hypersensitivity

Answer 7

an excessive or inappropriate response of the immune system to a sensitizing antigen

Question 8

what are the 2 main cytokines released in degranulation and their function?

which hypersensitivity reaction is this?

Answer 8

• 2 main cytokines = histamine and leukotriene → released from mast cells during degranulation
• histamine
  1. increase permeability
  2. vasodilation
• leukotriene
  1. causes bronchoconstriction
• this is a type I hypersensitivity reaction → mast cells degranulate → histamine and leukotriene are released

Question 9

autoimmunity treatments

Answer 9

autoimmunity treatment = immunosuppressive therapy

1. corticosteroids and cytotoxins = immunosuppressants
2. tumor necrosis factor (TNF) inhibitors
3. therapeutic plasmapheresis → plasma exchange