Immunodeficiencies - WikiBlood

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Introduction

Like any system in the body the immune system can go wrong. Autoimmunity is when the immune system begins to attack itself. Immunodeficiency is when the immune system fails to protect itself from disease.

If the immunodeficient defect is present at birth and is therefore a result of a genetic or developmental abnormality, it is called primary immunodeficiency.

Secondary immunodeficiency, soemtimes called aquired immunodeficiency, is the loss of immune function during life, caused by exposure to harmful agents.

Primary Immunodeficiency

Deficiencies of Innate Immunity

Canine Cyclic Haematopoiesis

• Also called Grey Collie Syndrome
• Autosomal recessive
• Insertion mutation in AP3B1 gene
• Diluted grey coat colour, stunted growth, poor wound healing
• Neutropenia every 2 weeks which lasts 3-4 days due to cyclic production of cells from bone marrow
• Recurrent infections, e.g. pyrexia, diarrhoea, gingivitis and arthritis

Canine Leukocyte Adhesion Deficiency (CLAD)

• Occurs in Irish Setters
• Missence mutation of -Cys-36-Ser- in CD18 molecule
  • CD18 is required for neutrophil migration and phagocytosis
• Recurrent bacterial infection
• Neutrophilia (neutrophils remain in the blood and are unable to fight infection in the tissue)

Bovine Leukocyte Adhesion Deficiency (BLAD)

• Occurs in Holstein cattle
• Missence mutation of -Asp-128-Gly in CD18 molecule
• Recurrent infection, e.g. pneumonia

Deficiencies of Adaptive Immunity

Equine Severe Combined Immune Deficiency (Equine SCID)

• Autosomal recessive
• Occurs in 2-3% of Arabian foals
• Defect in DNA-dependent protein kinase gene
  • Gene codes for a DNA repair enzyme involved in V(D)J recombination for antigen receptors of lymphocytes (e.g. Ig and TCR)
• No functional B or T cells
• Foals develop infections (usually aorund 8 weeks of age as maternal antibody in colostrum wanes around this time)
• Foals usually die from bronchopneumonia

Canine X-Linked Severe Combined Immune Deficiency (Canine SCID)

• Affects Basset Hounds and Corgis
• X-linked recessive defect in the gene conding for the IL-2 receptor
  • IL-2 receptor is a receptor for the cytokine IL-2 which causes T cells to proliferate
• Causes lymphoid hypoplasia, stunted growth and increses the animal's susceptibility to infection
• Animal usually dies from pneumonia or sepsis as the level of maternal antibody decreases

Selective IgA deficiency of German Shepherd Dogs

• Poorly understood
• Linked to other disease syndromes such as deep pyoderma, inflammatory bowel disease, anal furunculosis and disseminated aspergillosis
• IgA deficiency so more susceptible to mucosal disease

Immunodeficiency of Weimaraners, Irish Wolfhounds and Miniature Dachshunds

• Unknown aetiology
• Inherited defects
• Low levels of circulating IgM and IgG
• Impaired neutrophil function
• Causes recurrent pyrexia and infections
  • E.g. Rhinitis and bronchopneumonia in Irish Wolfhounds due to low IgA
  • E.g. Pneumocytosis in Miniature Dachshunds due to low IgG

Severe Combined Deficiency

Severe Combined Immune Deficiency(SCID)

• No functional B or T cells

Arthymic nude mice (no thymus)

• No functional T cells

Knock-out mice

• E.g. Gene coding for CD4, CD8, IL-10 removed

Secondary Immunodeficiency

Toxic Causes

• Poisons

Iatrogenic Causes

• Drugs
  • Corticosteroids
  • Ciclosporin
  • Cytoxic cancer therapy

Other Causes

• Malnutrition

• Chronic disease

• Stress

• Senescence

References

• Ivan Roitt: Essential Immunology, Ninth edition

• Goldsby, Kindt, & Osbourne KUBY Immunology, Fourth edition

• Dr Brian Catchpole BVetMed PhD MRCVS

Creators

Natalie Brown