Autoimmunity Vs Autoimmune Disease Flashcards
Define autoimmunity
Immune response against host due to loss of immunological tolerance of self antigens
Define autoimmune disease
Conditions caused by tissue damage or disturbed physiological responses due to immune response against self antigens
Difference between organ specific + non organ specific autoimmune disease
- organ specific: one or multiple self antigens within one single organ or tissue
- non organ specific: widely distributed self antigens throughout the body (all cells)
Describe immunological tolerance
A diverse range of host processes that prevent potentially harmful immune responses against host antigens
Describe the mechanisms of induction of autoimmunity - breakdown of tolerance
- breakdown of central tolerance: failure to delete auto reactive T or B cells
- breakdown of peripheral tolerance: Treg defects | impaired immunomodulation | altered self antigens
- activation of auto reactive B cells: T cell independent activation of B cells |carrier effect (complex foreign self antigens)
Examples of organ specific autoimmune diseases
What type of hypersensitivity reaction occurs in each?
- Hashimoto’s thyroiditis - type IV
- type 1 DM - type IV
- MS - type IV
- Good pasture’s syndrome - type II
- Addison’s disease - type II
- Graves disease - type II
- Myasthenia gravis - type II
- Pernicious anaemia - type II
Examples of non organ specific autoimmune diseases
What type of hypersensitivity reaction occurs in each?
- autoimmune haemolytic anaemia - type II
- RA: type III
- systemic lupus erythematosus - type III
- Sjögren’s syndrome - type IV
Diagnosis of autoimmune disease
- presence of autoantibodies/autoreactive T cells
- levels of autoantibodies correlate with disease severity
- autoantibodies/autoreactive T cells found at the site of tissue damage
- transfer of autoantibody or autoreactive T cells to healthy host induces an autoimmune disease
- family history
- clinical benefit provided by immunomodulatory therapy
Define specificity
The ability of the test to excluded those who do not have the condition
Define sensitivity
The ability of the test to identity those with a condition
think that you’re sensitive to something about you > you have the condition
What disease is produced if there are maternal autoantibodies to;
- platelets
- RBCs
- TSH receptor
- acetylcholine receptor
- nuclear antigen SSA/Ro
- platelets: thrombocytopenia
- RBCs: haemolytic anaemia
- TSH receptor: neonatal Grave’s disease
- acetylcholine receptor: neonatal myasthenia gravis
- nuclear antigen SSA/Ro: neonatal systemic lupus erythematous
Primary vs secondary autoantibodies
- primary: drive the disease
- secondary: occurs later in disease course + do no drive disease
What genetic factors trigger autoimmunity?
- increased risk with affected sibling/identical twin
- AIRE mutations that affect central tolerance
- autoimmune disease associated with MHC variant
What environmental factors trigger autoimmunity?
Hormones
Infections
Drugs
Are autoimmune diseases more common in men or women?
Women
Infectious causes of Gillian barre syndrome
What antigen is involved
- campylobacter jejune glycoproteins
- myelin-associated gangliosides
