Type IV Hypersensitivity Flashcards
What is important in type IV that is not important in the other types of hypersensitivity?
*cellular immune response is important
Type IV
- injected antigen
- APCs
- T cells
tuberculin:
inflammatory response in the skin of an animal infected with TB following intradermal injection of TB
How long does type IV take?
24-72hrs to see inflammatory rxn
*delayed**
What can we observe at site of inflammation?
increased number of macrophages
TB tests:
- simple: false pos=mycobacterium
- false neg= animals w/ advanced or early TB (igG)
Most common test for TB
Single intradermal in tail folds of skin
also there is:
comparative, short thermal, stormont
Tubercle formation
a histological section of lymph node, dark center mass is caseous material. Surrounded by layers of macrophages & lymphocytes & walled off by fibroblasts
Cytotoxic T cells release
proinflammatories which go to the chemicals injected
Atopic dermatitis
type I hypersensitivity
Allergic contact dermatitis
type IV hypersensitivity
Measurement of cell proliferation
-T cells proliferate after contact w/ mitogen (specific antigen)
-Thymidine is incorporated into the DNA of dividing cells
the uptake is measured by radioactivity of the cells
Measurement of cell death
- measurement by detecting release of chromium-51 by dying cells
- release is triggered by cytotoxic T cells or NK cells
IFN-y production enzyme linked immunosorbent assay
plasma is assayed for any interferon produced
can be used for dx if TB in cattle & deer
ELISpot= enzyme linked immunospot
hound cytokine detected using enzyme labeled antiglobulin
