AED - Immunopathology - Week 1 Flashcards

1
Q

Are lymphatic vessels present intraocularly? What about in the eye and orbit? What is this a major factor of?

A

None are present intraocularly, and generally scarce in the eye and orbit
Major factor in the eyes immune privilege

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2
Q

List where in the eye lymphatic vessels can be found (7).

A

Conjunctiva
Limbus
Lacrimal gland
Eyelid
Optic nerve dura sheath
EOMs
Choroid (controversial)

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3
Q

What are MALTs?

A

Mucosa-associated lymphoid tissue where B and T cells can migrate to

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4
Q

What kind of cells are mainly found in lacrimal gland MALTs? What other cells are they associated with?

A

IgA-positive plasma cells
Associated with grouped and individually patrolling T cells

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5
Q

What two cells are predominantly found in MALTs found in canaliculae and lacrimal mucosa?

A

T cells and macrophages

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6
Q

Define intraocular immune privilege.

A

Sites in the body where foreign tissue grafts can survive for extended or indefinite periods of time, whereas similar grafts placed at conventional body sites are acutely rejected.

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7
Q

Are there excessive immune responses within the blood-ocular barrier?

A

No

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8
Q

Give three pieces of evidence for intraocular immune privilege.

A

Foreign tissue placed in the anterior chamber is not rejected
Unrestricted growth of allogenic (non-self) tumour cells inside the eye
Aqueous and vitreous fluids inhibit inflammatory cells in vitro

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9
Q

Expression of what compound and by which cells contributes to intraocular immune privilege?

A

TGF-B2 by pigmented cells in the eye
High levels of TGF-B2 are found in eye, not so in other tissue

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10
Q

How does TGF-B2 inhibit immune response in the eye?

A

Disarms T-cells that cross the pigmented epiithelium

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11
Q

What is the role of a-MSH in the eye (2)?

A

Inhibits macrophage activation and promotes production of anti-inflammatory factors

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12
Q

List three mechanisms of intraocular immune privileges and explain how if applicable.

A

Physical barrier
-efficient BRB, no efferent lymphatics
Inhibitory microenvironment
Active regulation of the immune response
-anterior chamber acquired immune deviation

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13
Q

Define the following:
Autoimmunity
Hypersensitivity
Immune deficiency

A

Autoimmunity - failure to distinguish self from non-self
Hypelsensitivity - excess/inappropriate response
Immune deficiency - absent/inadequate response

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14
Q

What results almost exclusively from a viral or chlamydial infection and sensitivity to topical medication and in what two regions of the eye? Where are the vessels, and is there a damaging collateral response?

A

Follicles: raised gelatinous lesions of the upper and lower tarsal and bulbar conjunctiva
Surrounding (not central) blood vessels
No damaging collateral response

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15
Q

What are conjunctival follicles histologically and are they present on a normal conjunctiva?
When these regions are selectively stained for B-lymphocytes, what is revealed and what does it resemble?

A

Flat, defined accumulations of lymphocytes and are present in normal conjunctiva
With selective staining, it indicates a germinal centre, much like lymph nodes

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16
Q

Are T-cells found in conjunctival follicles?

A

Yesd, much like lymph nodes

17
Q

What cells does the diffuse layer of the conjunctival MALT contain (5)?

A

Plasma cells
Lymphocytes
Mix of CD4+ and CD8+
Unactivated B-cells

18
Q

What vessels of note can be found in the diffuse later of the conjunctival MALT and what do they do?

A

High endothelial venules, which are specialised vessels that promote leukocyte extravasation

19
Q

Describe, in four steps, the model of pathogenesis of follicular hyperplasia in the conjunctiva.

A

Follicular and diffuse layers are beneath the conjunctival epithelium
Antigen exposure occurs
Proliferation of appropriate lymphocyte population to produce plasma and memory cells
Plasma cells migrate from the follicle to the diffuse layer, releasing antibodies, causing follicular hyperplasia, and memory cells proliferate

20
Q

List 6 clinical features of a rejected corneal graft.

A

Red eye
Cells and plasma proteins in the anterior chamber
Corneal cellular infiltration
Oedema
Corneal vascularisation
Keratic precipitates

21
Q

Describe the histopathology of a corneal graft rejection.

A

Infiltration of donor corneal button with many CD4+ and CD8+ T cells, which move in from host limbal vessels

22
Q

What do corneal neovascularisation and lymphangiogenesis increase the likelihood of and how?

A

Graft rejection via a reflex arc to lymph nodes

23
Q

Define rheumatoid arthritis and 4 ways it can manifest in the eye.

A

Cell mediated autoimmune condition
Uveitis, episcleritis, scleritis, dry eye

24
Q

Describe the histopathology of ocular changes associated with rheumatoid arthritis (4).

A

Lymphocytic and plasma cell infiltration of the iris
Cells also in the anterior chamber and andherent to the corneal endothelium
Presence of Russell bodies
Advanced scleritis
Evidence of granulomatous cell formation around necrotic collagen

25
Q

Define Russell bodies.

A

Inclusions in/ modifications of plasma cells which contain excessive immunoglobin

26
Q

Advanced scleritis in rheumatoid arthritis is driven by the activity of what two cells?

A

T-cell and macrophage activity.

27
Q

What is the most common ocular manifestation of AIDS?

A

Retinopathy

28
Q

What viruses are generally responsible for AIDS retinopathy (2)?

A

HIV or CMV

29
Q

List three hallmarks of CMV retinitis.

A

Mild granulomatous inflammation in the retina and choroid
Retinal necrosis
Choroid granuloma

30
Q

What do retinal cells show in CMV retinopathy?

A

Multiple inclusion bodies in their cytoplasm

31
Q

What percentage of individuals have CMV with AIDS retinopath?

A

85=90%

32
Q

Are the hallmarks of CMV retinoapthy commonly seen in non-immunocompromised individuals?

A

No, rarely seen

33
Q

What kind of tumour is commonly seen in AIDS patients? What three structures of the eye can it involve? What is it largely due to?

A

Kaposi’s sarcoma - a vascular tumour
Can involved the eyelid, conjunctiva, and orbit
Largely due to reduction in CD4+ T cells