Immunology Flashcards
what are the 3/4 mechanisms of immunopathology
• Immunodeficiency = ineffective immune response
• Hypersensitivity reaction = overactive immune response
• Autoimmunity = inappropriate reaction to self
(also immune cell neoplasia)
what are the 3 general features of immunodeficiency diseases
o Increased susceptibility to infection
o Increased incidence of autoimmune disease
o Prone to virally induced cancers e.g. feline leukaemia virus
examples of innate immune system deficiencies
abnormal phagocyte function
complement deficiency
adaptive immune system deficiencies
B cell immunodeficiency (decreased immunoglobin production)
T cell immunodeficiency (decreased cell mediated immunity)
Combined – B and T cell (SCID)
primary vs secondary immunodeficiency diseases
primary are congenital, rare, and clinical signs develop after weaning
secondary are acquired, more common, and involve the animal initially having functional immunity, but subsequently the immunity becoming defective
causes of secondary immune deficiencies
o Failure of passive transfer
o Medical intervention e.g. chemotherapy, immunosuppressive drugs
o Infection of immune cells e.g. canine distemper virus, FIV, FeLV
o Hypercortisolaemia and stress
o Chronic disease = lymphoid depletion
o Environment e.g. starvation, malnutrition
o Old age (immunosenescence)
potential causes of failure of passive transfer
o Lack of colostrum ingestion – failure to suckle
o Lack of colostrum production – e.g. premature birth
o Absorption failure by newborn – something wrong with GIT
diagnostic approach to failure of passive transfer
• Index of suspicion based on history, signalment
• Measure IgG concentrations – stall-side testing kit
• Complete blood count
o Abnormal white blood cell count
o Toxic changes in white blood cells
• Serum biochemistry
o Low globulin concentrations
treatment of failure of passive transfer
IV administration of plasma containing immunoglobins (oral admin won’t work after 24 hours post-parturition as GIT is no longer able to absorb)
Antibiotics to treat infection
prevention of failure of passive transfer
• Prevention better than treatment
• Ensure the dam is healthy and vaccinated
• After birth, verify that the foal stands and nurses
• 12-18 hours after birth measure serum immunoglobins
o >8g/L = adequate
o <4g/L = failure
o 4-8g/L = partial failure
Iatrogenic immunosuppression
Acquired immunodeficiency due to administration of immune suppressant medication
Secondary opportunistic infections can occur - UTI, skin infections, blood stream infections
If an infection results, lower the dosage of the immune-suppressing meds and give antibiotics
hypersenstivity reactions
undesirable / harmful responses produced by normal immune system mechanisms.
Evolved to protect against infection – but overreact and react to harmless things, and react to self (autoimmunity) – can cause tissue injury and serious disease.
autoimmunity
an immune response directed against self-tissue, due to failure of self-tolerance.
Immune-mediated disease / autoimmune disease
the inflammation, tissue damage and resultant clinical signs that result from autoimmunity.
What’s the difference between autoimmunity and autoimmune disease?
Autoimmunity doesn’t always result in disease, but autoimmune disease is always due to autoimmunity.
What is the difference between autoimmunity and hypersensitivity?
Related abnormalities of the immune system
In autoimmunity, the immune system is reacting to self (no stimulus)
In hypersensitivity, the immune system is overreacting to a stimulus
why does autoimmunity occur?
genetic disposition
epigenetics - age, sex, lifestyle, diet
environmental triggers - infection, drugs, vaccines, cancer
