Inherited and Acquired Immune Deficiencies Flashcards
Innate immune system
- anatomic and physical barriers
- phagocytic cells (macrophages, DC, neutrophils)
Adaptive immune system
Recognizes/eliminates pathogens
- lymphocyte is major cell type
- T and B cells
Primary immunodeficiency diseases
Inherited defect for immune system components
- disease due to defect in particular protein or glycoprotein
Features of primary immunodeficiency
- affects a particular breed
- occurs in young littermates
- chronic recurrent infections
- infections of multiple body sites
- failure of infections to respond to standard antibiotic therapy
Primary immunodeficiency classifications
- dominant
- recessive: most common
- x linked
X linked immunodeficiency
Recessive X linked defect
- males affected
- females are carriers
Dominant immunodeficiency
Anyone inheriting the abnormal allele is affected
- are less severe and cause a reduction in function rather than a loss of function
Canine leukocyte adhesion deficiency
Autosomal recessive
- seen in Irish Red and White Setters
- neutrophils do not express integrin surface molecules, so they do not stick to endothelial cells
= bacteria in tissues survive and multiply more readily
Canine leukocyte adhesion deficiency highpoints
- persistent infection with extracellular bacteria
- infection cannot be cleared due to defective neutrophil function
Canine leukocyte adhesion deficiency symptoms
Puppies present with recurrent infections
- tend to have a high WBC count
- short lived response to antibiotics
SCID in foals
Severe combined immunodeficiency
- arabian foals
- autosomal recessive
SCID pathophysiology
Affected foals lack functional B and T cells
- incapable of producing antigen specific immune response
SCID genetics
Deletion in gene encoding a DNA-dependent protein kinase
- kinase is essential for T and B cells to complete gene rearrangements, which encode for surface antigen-specific receptor complexes
SCID foal symptoms
Foals appear normal at birth
- time of onset is determined by extent of transfer of passive immunity and extent of exposure to pathogens
- foals become susceptible as maternal immunity wears off
Most SCID affected foals present with ____ infections
Respiratory
SCID diagnosis
- blood work: show severely depressed lymphocyte count
- undetectable IgM concentrations by 3-4 weeks
- need to DNA test to confirm
No 2 _____ horses should be bred when trying to prevent SCIDS
Heterozygous
X linked SCID
Males
- bassett hounds and corgis
- peripheral T cell lymphopenia
- B cells do not undergo isotype switching to IgG
- reduced production of NK cells
XSCID genetics
Mutation in gene encoding for IL-2 receptor
- dysfunctional IL-2 receptor
- defect in T cell function and development
XSCID clinical presentation
Appear normal at birth due to maternal antibodies
- failure to thrive
- increased susceptibility to bacterial and viral infections
IgA deficiency in dogs
Recurrent upper respiratory infections, with occasional otitis and dermatitis
IgA deficiency pathophysiology
Infection begins in the first few month of life
- can also be present in adults
- 20% of dogs diagnosed before 1 yr will revert to normal by 12-18 months
- 90% of dogs diagnosed after 1 yr will remain with the disease
C3 deficiency
Reported in Brittany Spaniels
- autosomal recessive
- homozygous with no detectable C3
- heterozygous with 50% normal C3 and animals are clinically normal
C3 is important for ____
Opsonizing bacteria
C3 deficiency clinical signs
Only seen in homozygous dogs
- increased susceptibility to bacterial infections
- supportive treatment
Cyclic hematopoiesis in Gray Collie
Autosomal recessive disorder
- severe cyclic neutropenia, platelet mediated bleeding, recurrent bacterial infection, coat dilutional color
Cyclic hematopoiesis clincial
Arrest of hematopoiesis at regular 11-14 day intervals
- neutropenia lasts 3-4 days and is followed by neutrophilia
- dogs rarely live past neonatal period
Secondary immunodeficiency diseases
Develop due to a secondary problem, not from immune defect at birth
- causes: infectious agents, drugs, and endocrine diseases
- horses: failure of passive transfer
HIV
RNA virus
- transferred via body fluids
- causes slow progressing diseases
HIV pathophysiology
Virus recognizes and binds to CD4 = cell entrance and replication of virus
- leads to infection of CD4+ T cells = activation and production of infectious virions
What cell types express CD4?
Macrophages, DC, and CD4+ T cells
HIV causes a slow decline of _____
CD4+ T cells and progression to AIDS
CD4+ cells have a critical role in promoting and maintaining ______
Cell mediated and humoral immune responses
What are the first sites of infection for HIV?
Oral and respiratory tracts
FIV
Lentevirus transmitted by cat bites
- initial viral replication and decline in CD4+ T cells = acute phase of infection
- progress to latent asymptomatic period followed by decline in CD4+ T cell numbers
FIV pathophysiology
With decreased CD4+ cells you get cytokine alterations and progressive immune dysfunction develop
- failing immune system allows for opportunistic infections, neoplasia, and wasting
_____ is common in FIV infected cats
Lymphoma
FIV management
- keep indoors and separated
- regular exams with blood work
- if sick, prompt identification of the secondary illness with treatment
Canine parvovirus
DNA virus
- trophism for rapidly dividing cells (GIT, bone marrow, lymphoid tissues)
Parvo timeline
Infection in GIT –> enteritis –> intestinal crypt necrosis, increased permeability and decreased absorption –> diarrhea –> mild = recovory OR severe = secondary infection and sepsis (DIC, death)
Infection in bone marrow
Destruction of leukocyte and lymphoid precursors –> neutropenia and lymphopenia = secondary immunosuppression –> secondary bacterial infections (bacteremia and septicemia)
Parvo clinical signs
Sudden onset of foul-smelling, bloody diarrhea
- vomiting
- fever
- ADR
Parvo treatment
- restore fluid and electrolyte balance
- prevent secondary infections
- control secondary complications
Secondary non-infectious causes of immunosuppression
- failure of passive transfer
- marrow diseases
- endocrine diseases
- immunosuppressive agents
- chemotherapy
