Lecture 10 Flashcards
(35 cards)
What are hypersensitivity reactions
Abnormal or undesirable state of immune reactivity which has deleterious effects on the host = immunopathology
What are the 4 classifications of hypersensitivity
- Type I or Immediate hypersensitivity
- Type II or antibody-mediated cytotoxic hypersensitivity
- Type II or immune complex hypersensitivity
- Type IV or delayed-type hypersensitivity (DHT)
Describe the 2 phases of immediate hypersensitivity (type I)
Phase 1
- Individual first sensitised to allergen
- Allergen-specific B cells mage IgE
- IgE binds to mast cells
Phase 2
- Upon subsequent exposure to allergen mast cells degranulate
-Rapid release of inflammatory molecules from mast cels
- Synthesis of other mediators
Where are Ag encountered that induce hypersensitivity type I
Mucosal sufaces
What is Atopy
Genetic predisposition to type I hypersensitivity
What do atopic individuals have predisposition to overreact to
Th2 immunity, high levels of IL-4, IgE
What are the main players in hypersensitivity
Th2 cells, IL-4, IgE, mast cells and eosinophils
Eosinophils in type I hypersensitivity
Large presence of eosinophils, attracted to mast cell degranulation products, presence of eosinophils at site is regarded as hall mark of type I
What happens to eosinophils in type I hypersensitivity
Degranulate to release own mediators
How are eosinophils activated
Mast cells and Th2 cells produce IL-5 and eotaxins which mobilise eosinophils from the bone marrow, eosinophils release complex array of molecules that contribute to acute inflammation, eosinophils exacerbate inflammation caused by mast cells
What are the clinical signs of hypersensitivity type I.
Hay fever, rash, itchy skin, asthma ect
What does Type I hypersensitivity result from
Excessive release of inflammatory mediators from mast cells, eosinophils and basophils
Clinical sings of atopy in dogs and cats (5)
- Pruritus or itching
- Licking of paws
- Over grooming
- Erythema (redness) and alopecia
- Thickening and increased pigmentation
When does anaphylaxis occur
When a section becomes systemic
How to diagnose type I hypersensitivity (5)
- Clinical history, age, breed, environment
- Allergin exkursion
- Comercial serum ELSIA
Intradermal skin testing
How to treat type I hypersensitivity (4)
- Avoid exposure to allergen
- Corticosteriods, su press inflammation
- Immunotherapy, allergy shots, Th2 to Th1, induce tolerance
- Anaphylaxis
What do type II antibodies react to
Surface of normal cells
with Type II what are normal cells destroyed by
Complement or cytotoxic cells
Type II: what can lesions result from
Destruction of the cells - delayed
How do blood transfusions work
RBCs have surface antigen
What happens if there is transfusion of miss matched blood
Stimulates an immune response, RBCs are agglutinated and lysed by Ab + complement, NK cels or removed by phagocytic cells
What are the major groups of blood to species
Canine: DEA 1.1 and 1.2,7 Feline: A, B Equine: A, C, Q Bovine: B, J Ovine: B, R
What causes haemolytic disease of the new born
Female sensitised to foetal ‘foreign’ blood group antigen during pregnancy as it makes Ab against foetal antigens. Suckling newborn absorbs colostral antibodies. Ab generated against foetal antigens react with antigens on blood cells of newborn causing rapid haemolyosis of newborn blood cells
How do immune complex form with type III
Immune complexes forms as a result of antigen-antibody completes ant this activated complex
