immunology 2 Flashcards
define hypersensitivity
hypersensitivity reactions are exaggerated or inappropriate immunologic responses occurring in the response to an antigen or allergen
Type 1
represents immediate-type allergic reactions mediated by IgE antibodies with mast cell activation as the major effector mechanism
Type 2
are defined as those that were driven by antigen-specific IgG, with the effector mechanisms being antibody mediated
Type 3
defined as those that were driven by antigen-specific IgG with the effector mechanisms being immune complex-mediated
Type 4
delayed or depicted as being driven by multiple cellular effectors including T cells and myeloids cells
Mast cells
derived from hematopoietic cells in the bone marrow
degranulate in response to crosslinking of surface IgE
Products of Mast Cells
histamine-vasodilation and edema
enzymes-destroy parasites, damage tissue
leukotrienes and prostaglandin-inflammation
IL-4-increased differentiation of plasma cells and production of IgE
IL-5 recruits and activates eosinophils
Urticaria
hives
dermal edema
most common in horses and dogs but can occur in all animals
characteristic of type 1 hypersensitivity in the skin
caused by chemicals, drug, insects bites or stings
Atopic dermatitis
atopy-tendency to develop type 1 hypersensitivity (Genetic predisposition)
environmental triggers-pollen, mold, food allergens
chronic pruritus/itching
typical lesion distribution
rhinitis/stuffy nose and asthma in about 15% of patients
differential diagnoses: ectoparasites, infectious dermatitis, flea allergy, food allergy
Anaphylaxis
rare and life threatening
dyspnea/difficult breathing, vomiting, diarrhea, collapse
Treatment-epinephrine-vasoconstriction
diphenhydramine-antihistamine
dexamethasone-reduce inflammation
fluids-improve circulation
terbutaline-bronchodilator
Testing for Type 1 hypersensitivity
blood test
intradermal test
diet testing for food allergies
immunotherapy (allergy shots)
repeated low dose exposure to allergens
has been used in cats and dogs
mechanisms-decreased mediator release from mast cells and basophils
increase number of regulatory T cells
Fewer Th2 cells
Production of IL-10 and TGF-B
Not effective for food allergies
Transfusion reactions
blood types are based on erythrocyte surface antigens (EAs)
Signs of a transfusion reaction
fever
hemolysis (anemia, icterus/jaundice, hemoglobinemia and hemoglobinuria, disseminated intravascular coagulation)
allergic (hives and itching)
Neonatal isoerythrolysis in horses
foal inherits RBC antigen that is foreign to the mare
mare sensitized to foals erythrocyte antigen during pregnancy, parturition, previous transfusion
foal nurses and ingests colostrum containing antibodies to RBCs
Hemolysis
