Immune Attack On Tissues: Autoimmuinity

Question 0

TSHR-stimulating antibodies in Graves’ disease

Answer 0

Involves anti receptor antibodies
Bind to TSH receptors expressed by thyroid follicular cells
-> stimulate TH production
Action is not regulated-> overproduction-> hyperthyroidism
Pituitary stimulation stops
Increased thyroid hormones-> thyroid proliferation-> increased metabolism
Can cross the placenta-> infant born with graves but then produces own healthy antibodies

Question 1

Autoimmunity definition

Answer 1

Damage to self tissues triggered by an adaptive immune response to bodies own tissue components
Autoantigens or cell mediated
Organ specific-> autoimmune response directed at a particular tissue/organs
Non organ specific-> systemic! effects tissues in various parts of the body. More common
Involve type II, III, IV hypersensitivity

Question 2

Graves opthalmopathy

Answer 2

Inflammation of extra ocular tissue
Production of mucho polysaccharide and associated oedema
Possibly due to cross reaction between a thyroid and ocular antigen
Pre tibial myxoedema-> same but in subcutaneous connective tissue

Question 3

Atopic thyroiditis

Answer 3

Destruction and fibrosis of thyroid tissue
Antibodies that block TSH receptors
-> hypothyroidism
Deposition of mucopolysaccharides in subcutaneous tissue-> primary myxoedema

Question 4

Hasimotos thyroiditis

Answer 4

Autoimmune destruction of thyroid cells
Anti-microsomal and anti-thyroglobulin antibodies
HLA DR5
Massive lymphocyte infiltration
Replacement of thyroid follicles
-> hypothyroidism
Detected in patients blood samples by the ability to bind peoxidase and thyroglobulin

Question 5

Pernicious anaemia

Answer 5

Autoimmune destruction of gastric parietal cells
Anti parietal and anti intrinsic factor antibodies
-> decreased intrinsic factor production
Blocking antibodies-> bind IF and block it’s interaction with B12
Binding antibodies-> inhibit binding of IF to Ileal receptors
-> reduced B12 absorption from gut as IF helps B12 bind to intestines
B12 required for DNA sythesis-> cells can’t replicate-> decreased RBC production-> anaemia

Question 6

Type 1 diabetes

Answer 6

Autoreactive T cells specifically target and destroy beta cells-> no insulin production
Anti-islet cell antibodies
Takes years to destroy all the beta cells

Question 7

Myasthenia gravis

Answer 7

Autoantibodies to acetyl choline receptors expressed on muscle cells at neuromuscular junction
Block binding of acetyl choline and induce internalisation and degradation of receptors
-> extreme muscle weakness due to lack of muscle stimulation

Question 8

Autoimmune haemolytic anaemia

Answer 8

Autoantibodies specific for erythrocyte surface antigens
Erythrocytes are opponised-> complement activation-> destruction by phagocytosis
Type II hypersensitivity

Question 9

Good pastures disease

Answer 9

Autoantibodies specific to type IV collagen-> bind to glomerular basement membrane
->Complement activated-> neutrophils-> tissue damage-> kidney failure
Some autoantibodies also bind alveolar basement membrane-> lung damage

Question 10

Pemphyigus

Answer 10

Autoantibodies bind to intercellular substances of skin epidermis
Some specific for desmoglien-> blistering inflammatory reaction

Question 11

Systemic lupus erythematosus

Answer 11

Non organ specific-> systemic
Autoantibodies to a range of ubiquitous cellular constituents, particularly nuclear
Anti nuclear antibodies-> specific for DNA
Uv light damages proteins-> can’t repair-> damage-> rash
Affects skin, brain, kidneys, bones
Immune complexes form and deposit

Question 12

Rheumatoid arthritis

Answer 12

Immune complexes formed by rheumatoid factors-> IgM, IgG autoantibodies that are specific for IgG
Detected in blood sample by ability to agglutinate IgG coated beads
Cellular involvement also seen-> synovitis