Dr. Noxon - Clinical Immunology

Question 1

1. Iocane powder comes from…?
2. Never go in against a Sicilian when…?
3. You must have known I was not a great fool, you would have counted on it. So clearly…?

Answer 1

1. Australia
2. Death is on the line
3. I cannot choose the wine in front of me.

Question 2

Learning Objective 1

Review autoimmune diseases of the semester (listed below) and give the basic mechanism of tissue damage (using the hypersensitivity schemes) when given the type of autoantibody produced in the disease. The autoimmune diseases of the semester are: pemphigus foliaceus, myasthenia gravis, systemic lupus erythematosus, and autoimmune hemolytic anemia

Answer 2

Pemphigus Foliaceous

• Type 2 hypersensitivity. Antibody forms to epidermal cell adhesion molecules, resulting in damage and vesicle formation.

Myasthenia Gravis

• Type 2 hypersensitivity. Antibody forms to acetycholine receptor, resulting in muscle weakness, megaesophagus, etc.

Systemic lupus erythematosus

• Type 2 and 3 hypersensitivities. Type 2 - antibody forms to erythrocytes, resulting in lysis and anemal. Type 3 - antibody forms to histones, resulting in accumulation of immune complexes.

Autoimmune hemolytic anemia

• Type 2 hypersensitivity. Antibody forms to erythrocytes, resulting in lysis and anemia.

Question 3

Learning Objective 2

Describe the basic mechanisms for RBC removal/destruction in immune mediated hemolytic anemia and explain the basic difference between intravascular and extravascular hemolysis.

Answer 3

• RBCs become opsonized with auto-antibody
• Intravascular hemolysis
  
  • opsonization results in complement activation, formation of the MAC, and cell lysis.
• Extravscular hemolysis
  
  • Macrophages in the spleen, liver, etc. recognize antibody through Fc receptors and phagocytose RBCs.
  • Phagocytosis is often incomplete, resulting in characteristic spherocytes.

Question 4

Learning Objective 3

Explain what a spherocyte is, how it is formed, and what it indicates.

Answer 4

A spherocyte is a spherical erythrocyte that has lost its discoid shape because of loss of structural components.

When a RBC becomes coated with antibody, the antibody is recognized by macrophages in the spleen and liver (e.g. Kuppfer cells). The macrophages will attempt to phagocytose the cells. However, because of the fast movement of cells through capillaries, they often only take chunks out of the RBCs instead of complete phagocytosis. This results in the formation of spherocytes.

Spherocytes in the peripheral blood indicates an autoimmune disease against RBCs.

Question 5

Learning Objective 4

Describe how Dr. Noxon feels about pustules

Answer 5

Dr. Noxon get really excited about popping pustules.

Nobody cares about Dr. Noxon

(Words of Dr. Brown)