Abnormal Immunity - Immunodeficiency and Autoimmunity

Question 1

Immunopathology

Answer 1

Disease characterized by abnormal or inappropriate immune responses

Major conditions include:

hypersensitivity reactions

Immunodeficiency

Autoimmunity

Question 2

Immunopathology:

Autoimmunity

Answer 2

• Immune responses directed agianst self
• Immune mechanisms that mediate autoimmunity are the same that mediate reactions agianst exogenous antigens
  
  • only difference is the source of the antigen

Question 3

Autoimmunity:

Mechanisms

Answer 3

• Several general theories have been made about the origin of autoreactive immunity
  
  • release of sequestered antigens
  • Alteration of self antigen
  • Alteration of immune reactivity

Question 4

Autoimmunity:

Mechanisms

Release of sequestered antigens

Answer 4

• Some substances in the body are not normally exposed to the immune system
• These include:
  
  • myelin
  • Lens
  • Sperm

Question 5

Autoimmunity:

Mechanisms:

Alteration of self antigens

Answer 5

• Self antigens may be modified so that they are no longer recognized as self
  
  • viral alteration of cell membrane features
  • Chemical alteration of cell membrane

Question 6

Autoimmunity:

Mechanisms:

Alteration of immune reactivity

Answer 6

• There is a loss of tolerance to self antigen
• Autoreactive B- and T- lymphocytes are normally present, but non-functional
  
  • changes may occur that allow functions of these cells to be manifested

Question 7

Autoimmunity:

Predisposing Factors

Answer 7

• Genetic Predisposition:
  
  • certain conditions have definite inherited patterns of breed or familial occurrence
• Gender Predisposition:
  
  • Autoimmunity is more common in females
    
    • over 75% of cases of systemic lupus erythematosis are diagnosed in females
  • Comparative levels of estrogen and testosterone can influence autoimmunity

Question 8

Autoimmunity:

Manifestation:

Autoimmune Thyroiditis

Answer 8

• Antibodies are produced against the thyroid epithelium or thyroglobulin
• Common cause of hypothyroidism in dogs

Question 9

Autoimmunity:

Manifestation:

Periodic Ophthalmia

Answer 9

• Anti-leptospiral antibodies that are cross reactive with corneal self antigens cause anterior uveitis and vision deficiencies

Question 10

Autoimmunity:

Manifestation:

Autoimmune Skin disease

Answer 10

• Antibodies are produced to various components of the epidermis
• Variety of different syndromes exist
  
  • pemphigus vulgaris
  • Pemphigus foliaceous

Question 11

Autoimmunity:

Manifestation:

Autoimmune Hemolytic Anemia

Answer 11

Antibodies agianst erythrocytes result in complement or leukocyte-mediated hemolysis

Question 12

Autoimmunity:

Manifestation:

Autoimmune Thrombocytopenia

Answer 12

• Anti-platelet antibodies destroy platelets and predispose to hemorrhage

Question 13

Autoimmunity:

Manifestation:

Myasthenia Gravis

Answer 13

• Antibodies are produced agianst acethylcholine receptors of neuromuscular junctions causing weakness and muscle atrophy

Question 14

Autoimmunity:

Manifestation:

Systemic Lupus erythematosis

Answer 14

• Autoantibodies are directed against a variety of tissues most likely due to a loss of immunoregulation
• Antibodies are commonly formed against nucleic acids, erythrocytes, platelets, muscle, skin, lymphocytes

Question 15

Immunopathology:

Immunodeficiency

Answer 15

• Immunological defects that lead to depression of certain immune functions and increase susceptibility of infectious disease
• Any component of the immune system can be affected

Question 16

Immunodeficiency:

Mechanisms:

Inherited defects

Answer 16

• Genetic abnormalities result in the failure of proper development of the immune system

Question 17

Immunodeficiency:

Mechanisms:

Acquired defects

Answer 17

Exposure to certain infectious agents or chemicals, or nutritional deficiencies

Question 18

Immunodeficiency:

Manifestation:

Combined Immunodeficiency (CID)

Answer 18

• Come inherited defects involve multip;e immune cells
  
  • CID is most common in arab foals, but similar syndromes are reported in dogs, mice, and other species
  • Functional B- and T- lymphocytes are absent or decreased
  • Affected animals usually die before 6 months of age due to infectious disease

Question 19

Immunodeficiency:

Manifestations:

Selective Immunodeficiency

Answer 19

• Certain genetic defects involve specific immune cells
  
  • B-lymphocytes:
    
    • IgM deficiency in arabs and doberman pinschers
    • IgG deficiency in dogs and cattle
  • T-Lymphocytes:
    
    • Trait A-46 in friesian cattle

Question 20

Immunodeficiency:

Manifestation:

Viral-induced Immunodeficiency

Answer 20

• Large numbers of viruses can alter immune functions
  
  • some viruses destroy lymphoid cells and tissues
  • Some viruses cause lumphocyte dysfunction
• Viruses that destroy lymphoid cells and tissues include:
  
  • Canine Parvovirus
  • Canine Distemper virus
  • Feline panleukopenia virus
  • Bovine virus diarrhea virus
• Viruses that cause lymphocyte dysfunction include:
  
  • feline leukemia virus
  • Feline immunodeficiency virus
  • Bovine Leukosis virus
  • Equine infectious anemai virus
  • Mareks disease Virus

Question 21

Immunodeficiency:

Manifestation:

Chemical-induced Immunodeficiency

Answer 21

• Various chemicals reportedly induce immunosuppression
  
  • Halogenated biphenyls
  • Certain Heavy metals
  • Mycotoxins

Question 22

Immunodeficiency:

Manifestations:

Nutrition-induced Immunodeficiency

Answer 22

• Severe malnutrition or starvation will depress immune function
• Deficiencies of certain vitamins or minerals can suppress immune response
  
  • Zinc, Magnesium
  • Vitamins A, and B

Question 23

Immunodeficiency:

Manifestation:

Failure of Passive Transfer

Answer 23

• Colostral antibodies are not obtained by the newborn
• Neonates not receiving colostrum are predispoded to infections early in life.