10 - Type III Hypersensitivity Flashcards
How do we define type 3 hypersensitivity?
Immune (Ag-Ab) complex dz
-antigen typically from a pathogen, complexes filtered out or precipitate and then cause complement inflammation via classical pathway that attracts neutrophils, promotes inflammation
present of immune complex leads to damage of host tissue
WHat is the mechanism in which type 3 hypersensitivity works?
Ab binds to Ag - some Ab’s bind and activate complement which attracts neuts, bind macro’s and mast cells to release molecules that stim inflam, then release a variety of mediators that damage blood vessels and tissues
-all of this can be normal and help destroy the antigen
lg amount of complexes cause excessing activation and dz that tmay cause local/systemic effects
Ex lungs (local), kidneys/joints (systemic)
What is hypersensitivity pneumonitis?
Local hypersensitivty of inhaled antigens caused by heat tolerant bacteria growing on damp hay produce small spores that are inhaled into lungs
Ag-Ab complexes deposited into the lungs in which after 5-10 hrs after exposure to moldy hay, the whole lung is affected and causes inflammation such as fibrosis in chronic cases
steroids may be benefitial
What are the differences from asthma in cats? Type I vs Type III
Type of inflam cell
- eosinophils in asthma
-neutrophils in type III hypersensitivity
Response to bronchodilators
both respond
What are some other examples of type III hypersensitivity reactions?
Reccurent airway obstruction or heaves, and inflammatory airway dz in horses
Allergic pneumonitis of cattle (atypical interstitial pneumonia of cattle, hypersensitivity pneumonitis) and people (farmer’s lung)
What are the clinical signs and treatment of type 3 hypersensitivity?
clin signs - cough, increased RR and wheezing
Tx by removing contact with allergen, corticosteroids, bronchodilators
What is blue eye in dogs?
corneal edem and uveitis following Infectious Canine Kepatitis ( K9 adenovirus-1)
- by dz and vx w/ modified live vx
From immune complexes deposited in capillaries around Iris - neutrophils are then attracted to the area
Clins signs occur 1-3wks following infection
self-resolution once the virus is cleared
What is glomerulonephritis?
immune complexes are depositied in glomeruli that gets trapped int he glomerular capillaries and kidney damage occurs
needs a continuous source of antigen
can be from chronic viral or bact dz;
EIA of eq
pyometra + heartworm in k9s
lyme dz and feline leuk virus
How is glomerulonephritis diagnosed?
see proteinuria w/o evidence of UTI
biopsy req to confirm dx
tx by tx’ing primary cause, corticosteroids and ACE inhibators
WHat is purpura hemorrhagica in horses?
It is skin hypersensitivity seen 2-4 wks after S.equi infection (strangles/pneumonia) or vx
immune complexes deposited in blood vessels of skin
results in patchy, symmetrical, skin inflammated
May also have urticaria, severe SQ edema w/ heat, swelling, and pain. May oose serum, skin may slough, hemorrhages of mucosa and SQ tissues, sometimes GI signs
tx w/ corticosteroids
Clin signs anorexia, depression, fever, tachycardia +tachypnea
What are some examples of type 3 join hypersensitivity reactions in joints?
rheumatod arthritis, osteoarthritis, swollen joints, mild or moderate lameness
Give a quick summary of type 3 hypersensitivity? Its a problem caused by;
An important mechanism of dz?
how to tx
problem caused by complex of antigen, antibody (igG or IgM), followed y activation of complement and activation of neutrophils
important mechanism of fz by chronic exposure, local exposure such as lungs (heaves) and systemic circulation by deposition in capillary bed (ex in eyes, kidneys, skins, joints)
tx by removing source and corticosteroids
What is rheumatoid arthritis?
mmune omplex deposition in the joints is though to play a major role in pathology and progression of disease
