9. Immunology Flashcards
Why is the immune system important?
Protects against microbial invasion
How does the immune system work?
Functions through many different cell types sending and receiving messages that are delivered in the form of chemical signals. Involves hormones and cytokines which bind to specific receptors on target cells
What is immunity?
Functional or protective immunity describes having sufficient biological defences against a particular pathogen, which makes the animal non-susceptible to certain diseases.
What are specific and non-specific immunity components?
Specific- Act as barriers or eliminators of pathogens
Non-specific- Generation of pathogen specific immunity
What are sickness behaviours?
- lethargy
- loss of appetite
- muscle and joint pain
- fever
(All components of innate immunity)
What is the complement system?
An immediate response by the innate immune system. Its a response activated by both innate and acquired immune mechanisms
What is innate immunity?
Non specific, defences that an animal has at birth.
Includes:
- chemicals- lysozymes in saliva, stomach acid, sweat/tears are bactericidal
- flushing mechanisms- saliva, tears, urinating, cilia
- Phagocytic WBC
What is the inflammatory response?
The body releases histamine causing vasodilation resulting in the area of skin becoming reddened.
Permeability of blood capillaries is affected to enable plasma proteins and tissue fluid to leak causing swelling.
Chemical mediators are transported by tissue fluid, attracting WBCs which phagocytose dead and damaged tissue- essential for removing the initiating factor.
What are the 2 forms of acquired immunity?
- Mediated by antibodies- produced in response to a specific antigen, protects against extracellular invaders in the bloodstream (bacterium)
- Cell-mediated immunity- protects against intracellular invaders (Viruses)
What are antibodies?
Immunoglobulins- proteins produced by B lymphocytes in response to an antigen which are specific to the antigen that stimulates their production (Lock and key mechanism to form an immune complex)
What is the acquired immune system?
The ability to remember prior exposure to provide a faster, more effective response to exposure- can be passive or active
What is passive immunity?
An animal receiving antibodies from another animal- colostrum- the milk a newborn animal receives from the mother whom has been vaccinated.
Can only allow antibodies across during the first few hours post birth and can last 12 weeks in dogs and cats
What types of passive immunity is there?
- Artificial Passive Immunity
- Antisera
- Antitoxin
- Hyperimmune sera
What is active immunity?
- Natural active immunity- naturally coming into contact with antigens and the body creates antibodies to it
- Artificial active immunity- developing antibodies using a vaccine
What are the features of immunity?
- specificity- specific antibodies produced for a specific antigen
- Memory
- Recognition of ‘self’- when this fails autoimmune disease results
How do antibodies respond?
- primary response- the first time the body encounters an antigen it produces specific antibodies, which eventually fight off the infection. It also produces memory cells.
- Secondary response- the second time the body encounters an antigen it is recognised by the memory cells. An overwhelming production of antibodies prevents an infection establishing.
How are antibodies produced? (Humeral response)
B-lymphocytes mature, antigen stimulates B cells to develop plasma and memory cells, plasma produce antibodies (only live for one day), memory cells then retain the info on how to make again
How are antibodies produced? (cell mediated response)
T-lymphocytes mature in the thymus- 3 types:
- killer cells- destroy foreign cells
- helper cells- encourage b cells to change to plasma cells
- suppressor cells- suppress helper cells until the antigen is destroyed
What are the effects of failure of passive transfer?
Foals are born with little or no immunity to infection from outside organisms
There is a minimal amount of immunoglobulin-M (IgM) produced in utero, but insufficient to ensure adequate external protection
Foals acquire that immunity, initially, through the mare’s colostrum, which should be high in immunoglobulins
What is IgG?
maternally developed antibodies for 24 hrs post parturition (colostrum) - if this fails, mortality occurs (specifically in foals)
What are the causes of FPT?
- poor lactation
- poor colostrum quality
- maternal aggression towards the foal
What could FPT develop into?
- septicaemia, including septic joints or “joint ill”
- meningitis
- eye infections
- enterocolitis
- umbilical infections
- pneumonia
- death
How can FPT be diagnosed?
ELISA test (snap test) - adequate passive transfer= 800mg/dl lgG, anything less is failure
How is FPT treated?
colostrum administrated through nasogastric tube or per os.
plasma transfusion
How can we prevent FPT?
Snap testing foals early and making sure the mare is vaccinated.
