Immunodeficiency Diseases Flashcards
Autoimmune diseases vs immunodeficiency disease
Autoimmune: overly active immune response attacks own self
Immunodeficiency: immune system is not acting normally or strong enough
Define immunodeficiency
Absent or impaired immune function, usually as a result of problems with the numbers or function of neutrophils or lymphocytes, resulting in increased susceptibility to infection or neoplasia
Can be genetic
Can be acquired (nutritional or due to infection)
Describe combined immunodeficiency disease of Arabians (CID) (congenital)
A genetic disease of Arabian horses (autosomal recessive) (homozygous recessive individuals no in breeding pool, but risk of breeding 2heterozygous individuals)
Can be seen in dogs
The body has no lymphocytes or antibody -no T or B lymphocytes (why it is called “combined”)
Describe the diagnostic features of combined immunodeficiency disease of Arabians
Low numbers of lymphocytes (persistent): <1x109/L (lymphopenia must persist to diagnose)
Absences of circulating IgM after 25 days of life (after 25 days so that maternal antibodies are cleared) first clinical signs appear at 2-3 months of age
Failure to mount an immune response (don’t start to make antibodies of its own after maternal antibodies are gone)
Death before 5 months of age often due to pneumonia caused by unusual pathogens
Small thymus(no T cells), no lymphoid follicles or germinal centres(where B cells gather in lymphoid tissue) at necropsy
Describe thymus aplasia in nude animals (born hairless)
Mice, calves, cats and others: born hairless and with NO T cells (thymus aplasia)
B cells and antibody are present but less antibody produced because less stimulation by helper T cells
Die of viral disease
Autosomal recessive
Cyclic neutropenia of Collies
Autosomal recessive genetic condition that affects stem cells
Recognized by light coat and persistently grey nose
Cyclic (comes and goes) problem with the production of mainly neutrophils, platelets and other WBCs
Prone to infection and usually die as puppies
Tests are available for this gene
Prevent by not breeding carriers
Describe the 3 main causes of acquired (secondary) immunodeficiencies
1) toxins: environmental or complex organic molecules
2) nutritional: starvation depresses immune function
3) body condition: obesity promotes inflammation which decreases immune function
Describe how viral infections affect the immune system
1) May have no adverse affects
2) may transiently suppress the immune system (short term lymphopenia is common in viral infections)
3) may specifically target immune organs with severe or long lasting consequences
Viruses that target the immune system favours the survival of
The virus
Describe canine distemper virus
Virus infects epithelial cells (foot pad changes), nervous tissue and lymphocytes
Destruction of lymphocytes and macrophages
Profound immunosuppression -very little defence (see secondary infections and is a major contribution to signs)
Describe the type of virus seen in feline leukemia virus (FeLv)
A type of retrovirus -virus becomes inserted into a cat’s DNA (may persist until the cat dies)
Causes tumors and immunosuppression
Describe feline leukemia virus
Infected cats shed virus in saliva, nasal and all other secretions (grooming)
Free ranging cats most at risk, especially kittens
about 30% of cats are resistant to infections (immunity increases with age)
Initially invades lymphoid tissue of the upper respiratory tract And becomes viremic (circulates in the blood)
Infects other lymphoid organs and granulocytes precursors
Also seen in uterine infection of the fetus
Following infection of feline leukemia virus, describe the possible immune response
May completely clear the infection
May suppress infection but virus remains latent in bone marrow and can be activated by steroids and stress causing viremia
May allow the virus to be active with viremia but will either produce antibodies that prevent tumor development (still susceptible to FeLv degenerative diseases) or it will be susceptible to tumors and other diseases
What are the disease effects of FeLv
Immunosuppression
Following infection the virus mutates into variants that kill T cells
Causes lymphopenia
Depresses cell mediated immunity
Why are cats more susceptible to infections due to FeLv
B cells and antibody production is intact But there is immune complex diseases made
Highly suppressive variants may develop
