Type IV Hypersensitivity

Question 1

What is the principal effector cell of delayed-type hypersensitivity?

Answer 1

Macrophages

Question 2

What are the principal ANTIGEN-SPECIFIC effector cell of delayed-type hypersensitivity?

Answer 2

Th1 cells

Question 3

What causes induration used to diagnose type IV hypersensitivity?

Answer 3

Primarily fibrin released from damaged blood vessels

Accumulation of inflammatory cells contributes (minor)

Question 4

What are the 3 important cytokines of the DTH reaction?

Answer 4

TNFa, IFNy, and chemokines

Question 5

What are the 3 mechanisms of drug-induced DTH?

Answer 5

1) APCs process a protein (carrier) modified by a drug (hapten)
2) Hapten modifies a MHC-bound protein
3) Hapten modifies the MHC molecule

Question 6

DTH protects against

Answer 6

INTRAcellular pathogens

Question 7

Name 6 examples of type IV hypersensitivity

Answer 7

1. Infections
2. Contact Dermatitis
3. Allograft reject
4. Autoimmune reactions
   a. Type 1 Diabetes
   b. Equine Polyneuritis
   c. Multiple Sclerosis

Question 8

What is the primary difference between Equine Polyneuritis and Multiple Sclerosis?

Answer 8

Equine polyneuritis attacks peripheral nerves of the sacral and coccygeal regions. MS attacks the central nervous system.