TYPE IV HYPERSENSITIVITY

Question 1

Type IV hyper is

Answer 1

Cell mediated hypersensitivity
T cells and macrophages
No antibody involved
The lesion is called granuloma

Question 2

Application of hyper IV

Answer 2

Major veterinary application is intradermal (ID) skin tests

Question 3

How long does hyper IV take to happen

Answer 3

Also called delayed hypersensitivity
Takes at least 12 hours to develop
Response lasts for days

Question 4

Common disease that involve delayed hypersensitivity

Answer 4

Mycobacterial disease
Bovine TB
Johne’s disease

Question 5

Macrophages affect in hyper IV

Answer 5

Microbes live intracellularly in macrophages
Protected by waxy coat
Only partially effective
Large granulomas called tubercles often develop
Used to diagnose tuberculosis

Question 6

Skin testing for hyper IV is and how do cells react

Answer 6

Test for current or previous infection with intracellular bacteria
Antigen phagocytosed by Langerhans cells (a type of macrophage)
Move to LN
Activate memory t cells
Divide, migrate back to site of antigen
Attract more lymphocytes, macrophages and basophils

Question 7

Principle of skin testing for hyper IV

Answer 7

Inject purified, killed, cell extract intradermally
Use tuberculin to test for tuberculosis
Johnin for bovine paratuberculosis
Memory t cells respond to mycobacterial proteins in infected individuals
Observe for swelling 72-96 hours later

Question 8

What do a negative look like in skin testing

Answer 8

False +’ve arise due to cross reaction with similar proteins from other mycobacteria
Negative reaction- no previous or current infection, no memory T cells, purified extract does not elicit an immune response within 72 hours

Question 9

Allergic contact dermatitis is caused by

Answer 9

Some highly reactive chemicals bind to skin proteins
Formaldehyde
Poison Ivy
Insecticides in flea collars
Can provoke cell mediated immune response, delayed hypersensitivity

Question 10

Allergic contact dermatitis signs

Answer 10

Inflammation
Severe pruritus
Possibly skin vesicles

Question 11

Cell types needed in hyper IV

Answer 11

Lymphocytes and macrophages in lesion (granuloma)

Question 12

Allergic disease with delayed hypersensitivity?

Answer 12

Allergic contact dermatitis

Question 13

Hyper IV is used for

Answer 13

Used in testing for cell mediated immune response
Evidence of infection
Especially for mycobacterial disease