Immunology and the eye Flashcards
What is purpose of the immune system?
to identify and eliminate harmful microorganisms and harmful substances
How does the immune system identify harmful substances
by distinguishing self from non self and by recognising danger signals (i.e. from inflammation)
what are 3 key features of the innate immune system?
rapid - (mins to hours)
non-specific
no memory
What are 3 key features of the adaptive immune system?
gradual response (>days)
specific
memory
What is the physical protective barrier of tears
flushing
mucous layer anti-adhesive
what are lysosomes in tears protective agains?
gram -ve fungi
what are lactoferrin and transferrin in tears protective against
gram +ve fungi
how do tear lipids protect the eye ?
antibacterial to cell membranes
how is secretory IgA present in tears protective?
prevents attachment
what are the 3 cellular immunological components of tears?
neutrophils
macrophages
conjunctival mast cells
What does the acquired immune system require?
antigen presenting cells
lymphatic drainage to node
What is the only part of the eye with lymphatic drainage?
the conjunctiva
What are the features of the conjunctiva that help with the adaptive immune system
The only part of the eye with lymphatic drainage
dendritic cells act as APCs
MALT
commensal bacteria
what features of the cornea and sclera make immunocompromised?
avascularity
no lymphatics
down regulated immune environment
relative lack of antigen presenting cells
What is immune privilege?
being able to tolerate the introduction of antigens without eliciting an inflammatory immune response
Which parts of the body have immune privilege?
Brain/CNs
testes
placenta
eyes
what features give some parts of the eye immune privilege?
blood barrier
lack of lymphatic drainage
what is sympathetic ophthalmia?
A rare bilateral granulomatous uveitis
What can cause sympathetic ophthalmia?
penetrating trauma or surgery to the eye
What are the primary mediators in sympathetic ophthalmia?
T cells
What is the injured eye known as in sympathetic ophthalmia?
exciting eye
What is the non-insured eye known as in sympathetic ophthalmia?
sympathising eye
true/false
clinical both eyes appear the same in sympathetic ophthalmia, regardless of which is the exciting eye
true
How many different types of hypersensitivity are there?
4 types
What is a type I allergic reaction?
immediate hypersensitivity
What is a type II hypersensitivity reaction?
direct cell killing
What is a type III hypersensitivity reaction?
immune complex mediated
What is a type IV hypersensitive reaction?
delayed type hypersensitivity
What is the role of mast cells in allergic reactions?
Express receptors for Fc region of IgE antibody on their surface
what type of hypersensitivity is acute allergic conjunctivitis?
Type I
In a type II hypersensitivity reaction what are the cells killed by?
macrophages / natural killer cells
complement (membrane attack complex)
What type of hypersensitivity is Ocular cicatricial pemphigoid?
type II
what type of hypersensitivity is autoimmune corneal melting?
Type III
What type of hypersensitivity results in a corneal graft rejection?
Type IV
