Autoimmunity

Question 1

Distinguish between immunity, hypersensitivity/allergy, and autoimmunity

Answer 1

foreign material recognised and damaged - immunity
foreign material recognised and self material damaged - allergy/hypersensitivity
self material recognised and self material damaged

Question 2

explain the 4 types of hypersensitivity

Answer 2

ATOPIC (type I) - involves IgE, sensitive to an allergen and triggers inflammatory response on 2nd exposure

CELL/MEMBRANE REACTIVE (type II) - bind IgG to IgM/IgA antibodies on cells surface antigens cause destruction (haemolytic transfusion reaction)

IMMUNE COMPLEX (type III) - forms immune complexes that precipitate and deposit. Body’s attempt to remove can cause damage

CELL MEDIATED (type IV) - T-cell mediated, exposure to antigen triggers inflammatory response

Question 3

Broadly, explain Grave’s disease. What is seen at the neck?

Answer 3

autoimmune hyperthyroidism

swelling in neck where thyroids are found

Question 4

What kind of thyroidism is Graves’?

Answer 4

hyperthyroidism

Question 5

Explain the pathophysiology of Graves’ disease

Answer 5

auto-reactive b cells make anti-TSH antibodies that bind to receptors and thyroid stimulating antibodies which switches off TSH but no effect on b cells
=low TSH but high TH

Question 6

Consdiering TSH and thyroid hormones, what would be their levels?

Answer 6

low TSH

high TH

Question 7

How can babies get Graves from their mothers?

Answer 7

IgG can cross the placenta
baby can be born with symptoms of Graves’ disease but as they aren’t making it antibodies are removed by body’s natural degradation or plasmapheresis and then symptoms disappear

Question 8

What happens to the eyes in Graves’?

Answer 8

Grave’s opthalmopathy
inflammatory process of orbital tissue - affects ct and muscle surrounding the eyes
Retraction of lower eyelid
this can all cause protrusion of eyeballs

Question 9

Explain the pathophysiology of Graves’ ophthalmopathy

Answer 9

some expression of TSH on the CT of the eyes means autoimmune process translates onto orbital tissue
stimulates cytokines -> triggers GAGs -> brings mucinous substances that cause oedema

Question 10

What do TSHR-antibodies cause

Answer 10

autoimmune hypothyroidism

Question 11

Explain Hashimoto’s thyroiditis

Answer 11

swelling of thyroid tissue on the neck (goiter) caused by destruction of thyroid tissue as a result of proliferation of thyroid lymphocyte infiltrating the tissue

Question 12

Explain pernicious anaemia. What’s the cell under attack, and what are the 2 ways in which Abs bind to a target

Answer 12

B12 malabsorption and antibiotics attack stomach wall
Parietal cell is targeted - these cells secrete IF which help absorbs B12

B cells secrete antibiotics that bind IF to themselves - bind to either the part that would bind to B12 or to ileum

Question 13

Explain type 1 DM

Answer 13

beta cells specific T cells recognise peptides from insulin or glutamic acid decarboxylase and target beta cells in islets

Question 14

Explain autoimmune haemolytic anaemia

Answer 14

destruction of mature RBCs
antibodies bind to surface of RBC and opsonise (makes it more susceptible to phagocytosis) the surface which then bind to FCR on phagocytes and get destroyed or activates the complement pathway to form the membrane attack complex

Question 15

What is Goodpasture’s disease and what kind of hypersensitivity is it?

Answer 15

type II hypersensitivity

binds directly to glomerular basement membranes (type II collagen) - eventual kidney failure

Question 16

What happens in Lupus?

Answer 16

As cells die in patient’s body, those released constituents then form immune copmlexes with the antibodies, which then deposit and damage tissue.
Vasculitis. Damage to muscle, joints, CNS, kidneys etc. Pic on left shows kidney damage.
and damage to skin by UK which releases contents which then form immune comple