13 - Immunodeficiency Dz's Flashcards
What is the definition of immunodeficiency
absent or impaired immune function resulting in increased susceptibility to infection or neoplasia - may be a problem w/ innate or adaptive immune response
Why do immunideficiency happen?
bc of problems with # or function of neutrophils or lymphocytes
can be genetic, acquired - nutritional, toxic, infection
What is SCID?
severe combined immunodeficiency
a congentital immunodeficiency of the adaptive immune system - genetic in Arabians as autosomal recessive
most important congenital immunodeficiency syndrome in horses (but NOT the most important in foals - FPT)
What happens with SCID in foals?
No lymphocytes or Ig. Also happens in dogs
Foals cannot prod functional B or T lymphocytes -‘combined’
What are the diagnostic features of SCID?
Dx - persistently low #’s of lymphocytes (<1.0 x10^9/L of blood, should be 1.2-4.9)
Absent of circulating IgM after 25 days of life - takes time for colostral Ab to clear, first clin signs btw 2-8 wks
Failure to mount immune response
beath by 5-6mo - due to pneumonia
Necropsy of lymph nodes (lack lymphoid follicles and germinal centers, few cells present), spleen (absence of germinal centers and lymphoid sheaths around arterioles), thymus is small
What other tests and diagnosis can do do and use to identify SCID and prevent it?
Perform a CBC and hematology (severe lymphopenia - count is 0.2/10^9/L)
If its persists - SCID
Genetic testing available to test if carriers
What is thymic aplasia in nude animals?
A congenital immunodeficiency in mice, calves, cats and others
they are born hairless and No (or limited # of) T cells (thymus - aplasia or non-functional)
B cells and Ig are present but less Ig is produced bc T cells help to stimulate Ig production
often due of viral dz
autosomal recessive
Which immunodeficiency dz are autosomal recessive
SCIF, Thymic aplasia, canine cyclical neutropenia
What is canine cyclical neutropenia
A congenital imunodeficiency of the innate immunte system. AKA “gray collie syndrome”
autosomal recessive genetic condition affecting stem cells of smooth/rough collies
recognize by light coat and persistently gray or brown nose - collies should always have black noses
cyclic problem w/ neutrophils, platelets, other WBC. prone to infection + die as puppies, rarely live beyond 2-3yrs age. genetic testing available
What can aquired (2nd) immunodeficiencies come from?
toxins - enviro, complex organic molecules
nutrition - starvation depresses immune function, obesity promotes inflammation
Viral infections
What affects might acquired viral infections cause?
no adverse effect on immune system - transiently suppress the immune system (short term lymphopenia is a common in many viral infections), specifically target immune organs with severe or long-lasting consequences, targeting the immune system favors survival or the virus
What is canine distemper?
A virus has a predilection for epithelia cells, nervous tissue, lymphocytes, 2ndary lymphoid organs
destruction of lymphocytes
profound immunosuppression - 2ndary infections - major contributing factor to clin signs
What is feline leukemia virus (FeLV)
A type of retrovirus infection
about 70% of cats exposed to FeLV become infected (about 40% of the infected become viremic - about 90% of viremic cats become persistently infected so if 100 cats exposed, 70 infected, 28 viremic and 25 persistantly infected)
virus becomes inserted in catss DNA
causes tremors and immunosuppression
How might feline leukemia virus present?
its an infection - infected cats shed the virus in saliva, nasal and all other secretions, in-utero infection of fetus
free ranging cats are most at risk of becoming infections - especially young animals, about 30% of cats are resistant to infection, initially invades lympoid tissue or URT, become viremic, infections other lymphoid organs and granulocyte precursors
What happens in FeLV following infection?
The immune response may be completely clear the infection and suppress infection but remains latent in bone marrow - activated by steroids/stress and causes viremia
allows active infection with viremia - but can still prod antibodies to prevent tremor development (still susceptible to FeLV immunosuppressive dz) or susceptible to both tremors and other dz’s
