Exam 3: Hypersensitivity Type IV Flashcards
what type of immune response in type IV hypersensitivity
cellular immune response
what is the main cell involved in type IV hypersensitivity
T cells
type IV hypersensitivity characteristics
injected antigen
antigen presenting cells
T cells
tuberculin
what is tuberculin
inflammatory response in the skin of an animal affected with tuberculosis following intradermal injection of tuberculin
how long does it take for type IV hypersensitivity to appear
delayed hypersensitivity
inflammation in 12-24 hours
increased intensity of inflammation 24-72 hours
what causes false negative in tuberculin
animals with advanced tuberculosis (IgG)
test at early stage of infection
types of tuberculin tests in cattle
single intradermal
comparative
short thermal
stormont
single intradermal
use
advantages
disadvantages
use - routine testing
advantages - simple
disadvantages - prone to false negatives, poor sensitivity
comparative
use
advantages
disadvangates
use - when avian TB or Johne disease is prevalent
advantages - more specific than SID
disadvantages - more complex than SID
short thermal
use
advantages
disadvantages
use - use in postpartum animals and in infected animals
advantages - high efficiency
disadvantages - time consuming, risk for anaphylaxis
Stormont
use
advantages
disadvantages
use - use in postpartum animals and in advanced cases
advantages - very sensitive and accurate
disadvantages - three visits required, may sensitize an animal
different kinds of skin tests for tuberculin
Johnin = Mycobacterium avium var paratuberculosis
Brucella abortus
Mallein = Burkholderia mallei
Histoplasmin = Histoplasmosis
Coccidoidin = Coccidioidomycosis
allergic contact dermatitis
if reactive chemicals are painted onto skin, they may bind to skin proteins, and the resulting complexes are processed by Langerhans cells in the dermis
what can cause allergic contact dermatitis
poison ivy
haptens - chrome, nickel, resin, latex
Atopic dermatitis vs Allergic contact dermatitis
pathogenesis
Atopic dermatitis - type I hypersensitivity
Allergic contact dermatitis - type IV hypersensitivity
Atopic dermatitis vs Allergic contact dermatitis
clinical signs
Atopic dermatitis - hyperemia, urticaria, pruritis
Allergic contact dermatitis - hyperemia, vasiculation, alopecia, erythema
Atopic dermatitis vs Allergic contact dermatitis
distrubution
Atopic dermatitis - face, nose, eyes, feet, perineum
Allergic contact dermatitis - hairless areas, usually ventral abdomen and feet
Atopic dermatitis vs Allergic contact dermatitis
major allergens
Atopic dermatitis - foods, pollens, fleas, inhaled allergens
Allergic contact dermatitis - reactive chemicals, dyes in contact with skin
Atopic dermatitis vs Allergic contact dermatitis
diagnosis
Atopic dermatitis - intradermal testing, immediate response
Allergic contact dermatitis - delayed response on patch testing
Atopic dermatitis vs Allergic contact dermatitis
pathology
Atopic dermatitis - eosinophilic infiltration, edema
Allergic contact dermatitis - mononuclear cell infiltration, vesiculation
Atopic dermatitis vs Allergic contact dermatitis
treatment
Atopic dermatitis - steroids, antihistamines, hyposensitization
Allergic contact dermatitis - steroids
measurement of cell proliferation
the measurement of cell proliferation by detecting the uptake of tritiated thymidine
measurement of cell proliferation - what stimulates the cells to divide
cells are stimulated to divide by specific antigen or a mitogen
measurement of cell proliferation - where is thymidine incorporated
the thymidine is incorporates into the DNA of the dividing cells
measurement of cell proliferation - how is uptake measured
the uptake is simply measured by the radioactivity of the cells
measurement of cell death
the measurement of cell death by detecting the release of chromium-51 by dying cells
measurement of cell death - what triggers release of chromium-51
this release may be triggered by cytotoxic T cells or NK cells
IFN-y production - Enzyme Linked Immunosorbent Assay
the release of IFN-y by peripheral blood lymphocytes following exposure to tuberculin or to purified mycobacterial antigens
what can IFN-y production - Enzyme Linked Immunosorbent Assay be used for
this technique can be used for the diagnosis of tuberculosis in cattle and deer
in IFN-y production - Enzyme Linked Immunosorbent Assay, what is added to the blood and how long is it incubated for
tuberculin PPD is added to blood, and the mixture is incubated for 24-48 hours
in IFN-y production - Enzyme Linked Immunosorbent Assay, what is removed and what are they looking for
the plasma is then removed and assayed for any interferon produced
ELISpot = Enzyme Linked Immunospot steps
- antibody against cytokine added (IFN)
- lymphoid cells added and incubate
- cytokines secreted and bind to capture antibody
- cells washed off
- labelled antiglobulin followed by substrate added
- bound cytokine detected using enzyme labeled antiglobulin
IFN-y production - Enzyme Linked Immunosorbent Assay Steps
- antigen added to blood lymphocytes
- incubate
- cytokines secreted
- centrifuge
- remove supernatant
- measure cytokine such as IFN-y using ELISA
measurement of cell death steps
- target cells
- target cells take up chromium-51
- cytotoxic cells added
- incubate
- killed cells release chromium-51
- count radioactivity
measurement of cell proliferation steps
- lymphocytes
- antigen or mitogen added
- radioactive thymidine
- dividing cells take up H3-thymidine
- centrifuge and remove unbound thymidine
- count radioactivity
