Diseases caused by immune responses

Question 1

Type I Hypersensitivity

Answer 1

• Immediate
• IgE antibody by Th2 cell
• Mast cells, eos, and their mediators

Question 2

Type II Hypersensitivity

Answer 2

• Antibody mediated
• IgM, IgG antibodies against cell surface or extracellular matrix antigens
• Opsonization and phagocytosis of cells, complement and Fc receptor mediated recruitment and activation of leukocytes, abnormalities in cellular functions

Question 3

Type 3

Answer 3

• Immune complex mediated
• Immune complexes of circulating antigens and IgM or IgG antibodies
• Complement and Fc receptor mediated recruitment and activation of leukocytes

Question 4

Type 4

Answer 4

• T cell mediated
• CD4 T cells (Th1 and Th17), CD8+ CTLs
• Cytokine mediated inflammation, direct target cell killing

Question 5

Where are mast cells normally found?

Answer 5

• connective tissue (not in circulation)

Question 6

Why does delayed hypersensitivity happen?

Answer 6

• If a Th1 response to an infection activates microbes but fails to eliminate phagocytosed microbes–> chronic DHT reaction can develop–> activated macrophages undergo changes due to persistent signals–> multinucleated giant cells (think TB) try to contain the infection