Hypersensitivity

Question 1

Hypersensitivity

Answer 1

altered immunologic response to an antigen that results in disease or damage to the host

Question 2

Allergy

Answer 2

• hypersensitivity to environmental antigens
• reactions happen after 1st exposure
• often allergen is contained within a particle too large to be phagocytized or is protected by non-allergenic coat

Question 3

Autoimmunity

Answer 3

• disturbance in the immunologic tolerance of self-antigens
• body recognizes self antigen as foreign
• antigenic mimicry – foreign antigen similar to body’s antigen

Question 4

Alloimmunity

Answer 4

• immune reaction to tissues of another individual
• transplant rejection and transfusion rejections

Question 5

Type I

Answer 5

• IgW mediated
• works against environmental antigens (allergens)
• IgE binds to antibody receptors on the surface of mast cells – sensitizes
• histamine release – H1 (respiratory, vasodilation) and H2 (GI)
• manifestations = itching, urticaria, conjunctivitis, rhinitis, hypotension, bronchospasm, dysrhythmias, GI cramps
• genetic predisposition
• tests = food challenges, skin tests, lab tests
• can cautiously desensitize someone

Question 6

Type II

Answer 6

• tissue specific
• cells are destroyed by antibodies and complement
• cell destruction through phagocytosis
• soluble antigen enters the circulation and deposits on tissue, tissue destroyed by complement and neutrophil granules
• antibody dependent cell mediated cytotoxicity – transplant rejection
• causes target cell malfunction

Question 7

Type III

Answer 7

• immune complex mediated
• antigen-antibody complexes are formed and later deposited
• systemic or localized
• Raynaud’s disease = caused by temperature dependent deposition of immune complexes, blocks circulation and causes pallor, numbness, cyanosis

Question 8

Type IV

Answer 8

• cell mediated
• no antibodies, antigens stimulate T-lymphocyte activity
• activities activated:
  1. cytotoxic T-lymphocytes = attack and kill cells
  2. cytokine producing Th cells = produce cytokines recruiting and activates phagocytic cells

Question 9

Immediate hypersensitivity

Answer 9

• occurs within minutes to 2-3 hours
• anaphylaxis = most rapid and severe, immediate reaction
• cutaneous (localized) = painful local reaction, redness/swelling
• systemic (generalized) = allergic reaction to bee stings

Question 10

Delayed Hypersensitivity

Answer 10

• may take several hours and are at peak severity days after re-exposure

Question 11

Graft Rejection

Answer 11

• hyperacute = immediate and rare, pre-existing antibody to antigens of the graft
• acute = cell mediated immune response against unmatched HLA antigens (anti-rejection drugs)
• chronic = months or years, inflammatory damage to endothelial cells of vessels as a result of a weak cell mediated reaction against HLA antigens

Question 12

Graft vs. Host Disease

Answer 12

T-cells in the graft are mature and capable of cell-mediated destruction tissues within the recipient