Mechanisms Of Hypersensitivity Type IV - Bowden (Completed)

Question 1

What describes type IV Hypersensitivity? 38

Answer 1

Delayed type hypersensitivity

Question 2

What are the three types of delayed type hypersensitivities? 39

Answer 2

Contact - skin reaction (eczematous, eczema)

Tuberculin - induced by soluble Abs

Granulomatus (clinically most important)

Question 3

What are the two stages of delayed type hypersensitivity (type IV)? 40

Answer 3

Sensiztization –> elicitation

Question 4

What occurs during sensitization of DTH? 40

Answer 4

Ag is taken up by Das and presented via HLA class II

Question 5

What occurs during elicitation of DTH? 40

Answer 5

Th1 (CD4+) arrives and release pro inflammatory cytokines

Macrophages
Monocytes
inflammatory mediators

Question 6

What products are released in contact sensitivity (skin rash)? 41

Answer 6

CXCL-8, 9, 11 + TNF-α + IL-1 from keratinocytes

IFNγ from Th1

Question 7

What is happening during a TB test (PPD)? 42

Answer 7

Induces a delayed type IV hypersensitivity

Used to detect whether preformed T cells have memory and are activated against the injection

Question 8

What’s happening during a granulomatus reaction? 43

Answer 8

IC pathogens are able to resist killing by macrophages

Instead of enzymes, immune system “walls off” the pathogen to protect the rest of the body

Question 9

What else is correlated with granulomatus formation? 43

Answer 9

Chronic infections with Th1-like responses

Foreign bodies

Question 10

What are the type IV Immunopathologies? 44

Answer 10

multiple sclerosis (myelin proteins)

Rheumatoid arthritis

Crohns disease

Viral hepatitis

Contact dermatitis (poison ivy)

Type 1 Diabetes (pancreatic islet Abs)

Chronic infections (Tuberculosis)

Graft rejection

Question 11

What is Type I, II, III, and IV Hypersensitivities mediated by? 45

Answer 11

Type I - IgE mediated

Type II - IgG mediated (fixed)

Type III - Immune complex Mediated (soluble)

Type IV - Cell-mediated