Vet Hypersensitivities Flashcards
How are antibodies formed?
- heavy-chain locus multiple Variable (V) Diversity (D) and Junction (J) segments
- light-chain locus only multiple V and J segments
What creates antibody diversity?
Gene-rearrangement of V,D and J segments in pre-B cells
What is gene conversion?
- one DNA sequence replaces a homologous sequence (similar sequence)
- overwriting the gene
What are hypersensitivities?
There is failure in central and /or peripheral tolerance.
- The immune system reacts against harmless antigens
- Includes autoimmune diseases
What are the four types of Hypersensitivity?
- Type 1 (Antibodies against environmental antigens)
- Type 11 (antibodies against cellular antigens)
-Type 111 (antibodies in immune complexes) - Type 1V (cellular response to chemicals/ antigens)
How do Type 11 Hypersensitivities work?
- antibodies against host cells
- destroy cells using complement pathway
What diseases are examples of type 11 hypersensitivities?
- incompatible blood transfusions
- haemolytic disease of the new born
- myasthenia gravis
What happens to horses effected by haemolytic disease of the new born (Type 11 Hypersensitivities)
- female antigens encounter in utero red blood cells via leakage through placenta
- mother does not possess specific RBC antigen
- sensitised animals = previous blood transfusions from previous pregnancies
- anti-newborn RBC are produced
- anti- BBC pass into new born via colostrum
- move into new born circulation
- haemolytic disease
What are the symptoms for the haemolytic disease of the new born?
- born healthy, foals sicken after suckling
- weakness
- jaundice
- mucus membrane damage
- can lead to death
How do type 111 hypersensitivities work?
- caused by reactions against soluble antigens in the serum
- damage where the immune complex deposite
What are the symptoms of type 111 hypersensitivities?
- nepheritis
- vasculitis
-arthritis
What type 111 hypersensitivities diseases are there?
- canine adenovirus
- bovine viral diorrhea
- african swine fever
- equine viral arteritis
How do Type 1 hypersensitivities work?
- IgE mediated
- Inflamation caused by release of histamine and other molecules
- excessive Th2 envirionment
What is Atopy?
Excessive production of IgE
What are the symptoms of Type 1 hypersensitvity?
- dependent on route of exposure/ sensation/ dose and species
- itching
- mucous production
- during allergic anaphylaxis (coughing and vomiting)
What diseases are caused by type 1 hypersensitivity?
- canine atopic dermatitis
- sweet itch
- allergies to warble fly
What are the major cell types involved in type 1 hypersensitivities?
- mast cells
- basophils
- eosinophils
What are the major mediators of type 1 hypersensitivity?
- histamine
- leukotrienes and prostaglandins
- cytokines
- chemokines
- seritonin
What is the mechanism of type 1 hypersensitivity?
- first exposure to antigen
- antigen activation of Th2 cells and stimulation of IgE class switching in B cells = Production of IgE
- binding of IgE to mast cells
- repeated exposure to allergen = activates mast cell to release mediators
- basophils = also release histimine and can bind to IgE / amplifiying allergic responce by increasing IgE production
- Eosinophils = secrete Th2 cytokines, leukotrienes and prostoglandins
What do hypersensitivty vaccines consist of ?
- specific antigens of pathogen
- adjuvant
- trace amounts of molecules relating to production
What reactions can be dominant during type 1V hypersensitivities?
- CD8- T cell dominant (destruction of host cells, direct damge to host cells)
- CD4 T cell dominant (accumulation of T cells, indirect damage to host cells)
What mechanisum is completed during type 1V hypersensitivities?
- Antigen is injected into subcontanious tissue and processed by local antigen-presenting cells
- Th1 effector cell releases cytokines which act on vascular endothelium
- Recruitment of phagocytes and plasma to site of antigen injection causes visible lesion
What diseases are type 1V hypersensitivities?
- allergic contact dermititis
- insect bit hypersenstivity
What are Haptens (type 1V hypersensitivity)
A small molecule which, when combined with a larger carrier such as a protein, can elicit an immune response. (alter protein shape/fold)
