Immunology

Question 1

Layers of tear film

Answer 1

Lipid layer
Aqueous layer
Mucin layer

Question 2

Immune privilege

Answer 2

Tolerate introduction of antigens without initiating immune response to stop collateral damage

Question 3

ACAID

Answer 3

Anterior Chamber Associated Immune Deviation

Placement of foreign Ag into ocular microenvironment can induce a systemic form of tolerance to foreign Ag

Question 4

Sympathetic ophthalmia

Answer 4

Bilateral granulomatous uveitis due to trauma/surgery
Intraocular antigens to nodes activate T cells
T cells sent to both eyes (exciting and sympathising)

Question 5

Only part of eye with lymphatic drainage

Answer 5

Conjunctiva

dendritic cells act as APCs, MALT, commensal bacteria

Question 6

Type I hypersensitivity

Answer 6

Immediate
Mast cells have receptors for IgE
B cells produce IgE on encounter with allergen
Re-encounter - allergen binds IgE coated mast cells = release of vasoactive mediators

Question 7

Example of Type I

Answer 7

acute allergic conjunctivitis

Question 8

Type II hypersensitivity

Answer 8

Direct cell killing by NK cells/macrophages/complement

Question 9

Example of Type II

Answer 9

Ocular pemphigoid (blistering and ectropion)

Question 10

Type III hypersensivity

Answer 10

Immune complex mediated

Question 11

Example of Type III

Answer 11

Autoimmune corneal melting

RA

Question 12

Type IV hypersensitivity

Answer 12

Delayed, exaggerated response
Macrophages attract CD4 cells, clonal expansion
Re-exposure = macrophages attracted, inflamm mediators

Question 13

Example of type IV

Answer 13

corneal graft rejection (uncommon because of immune privilege)