## Mucosa associated lymphoid tissues (MALT)
<ul>
 <li>A specific immune system associated with mucosa&nbsp;</li>
 <ul>
 <li>
 Mucosa is more easily breached than skin and so considerable lymphoid tissue is concentrated
 within the mucosa to deal with new antigens
 </li>
 </ul>
 <li>
 Found in GI, respiratory, and GU tracts, conjunctiva (conjunctival associated lymphoid tissue) and glands of the ocular adnexa
 </li>
 <li>Comprises:</li>
 <ul>
 <li>Intraepithelial lymphocytes</li>
 <li>APCs (especially dendritic cells)</li>
 <li>IgA predominates in MALT</li>
 <li>Aggregations of lymphoid tissue (eg. Peyer&rsquo;s patches in GI tract; and tonsils)</li>
 </ul>
 <li>Antigen exposure stimulates antigen-specific IgA at all mucosal surfaces</li>
 <ul>
 <li>
 Recirculating IgA-producing B cells and T cells express homing receptors for addressins on
 endothelial cells of vessels supplying mucosal surfaces
 </li>
 <li>Addressins essentially direct movement of cells to various mucosal sites</li>
 <li>Memory T cells have &lsquo;first call&rsquo; on invading pathogens</li>
 </ul>
 <li>
 NB: there is no associated increase in antigen-specific IgG titres in the blood after a mucosal
 exposure and antigen specific T cells are not found in the spleen etc
 </li>
</ul>

## Antigen presenting cells in ocular tissues
<ul>
 <li>Bone-marrow derived dendritic cells expressing MHC Class II</li>
 <li>Tissue macrophages</li>
</ul>

 Note: the central cornea lacks APCs but they are found at the limbus

<ul>
 <li>Found in ciliary and iris epithelium, ciliary muscle, processes and TM</li>
 <li>
 Dendritic cells are found at the ora serrata in the neural retina and in the connective tissue
 around the choriocapillaris
 </li>
 <li>Ocular APCs cannot activate T cells like conventional APCs</li>
</ul>

## Aqueous
<ul>
 <li>Bacteriostatic properties: inhibits bacteria growth in vitro</li>
 <li>Contains numerous antibacterial proteins:</li>
 <ul>
 <li>Complement</li>
 <li>Immunoglobulin</li>
 <li>Defensins</li>
 <li>Beta-lysin&nbsp;</li>
 </ul>
 <li>Immunosuppressive properties</li>
 <ul>
 <li>Inhibits T cell proliferation (via transforming growth factor beta)</li>
 <li>Inhibits lymphokine production</li>
 <li>Suppresses macrophage and APC activity</li>
 </ul>
</ul>
<HotTopic>
 Immune privilege in the AC
 <ul>
 <li>Anterior chamber associated immune deviation (&ldquo;immune privilege&rdquo;)</li>
 <ul>
 <li>
 Immunological response to antigen entering the AC: systemic suppression of potentially
 damaging cell-mediated and humoral responses that might damage ocular tissue.
 </li>
 <li>Occurs within 1 week of introduction of antigen to the AC</li>
 <li>APCs process antigen</li>
 <li>Suppressor T cells develop which inhibit T-helper cells</li>
 <li>Normal cytotoxic T cell responses to antigen (T cells can still lyse target cells)</li>
 <li>Normal systemic antibody production to the antigen</li>
 <li>Requires an intact spleen&nbsp;</li>
 <li>Mediated by TGF-beta and other cytokines</li>
 </ul>
 </ul>
</HotTopic>

## Ocular immune privilege
<ul>
 <li>Protects ocular structures from potentially damaging immune-mediated inflammation</li>
 <li>Components&nbsp;</li>
 <ul>
 <li>Blood-ocular barrier</li>
 <li>Lack of lymphatics to the eye</li>
 <li>Soluble immune modulatory mediators in the aqueous (as above)</li>
 <li>Unique tolerance promoting APCs</li>
 <li>Note: a functioning eye-spleen axis is necessary</li>
 </ul>
</ul>

## Non-infectious intraocular inflammation
<ul>
 <li>Anterior segment: iridocyclitis</li>
 <ul>
 <li>50% of AAU (non-ranulomatous) associated with HLA-B27</li>
 </ul>
 <li>Posterior uveitis: multifocal choroiditis, retinal vasculitis</li>
 <ul>
 <li>Birdshot retinochoroidopathy (HLA-A29)</li>
 <li>Behcet&rsquo;s retinal vasculitis (HLA-B51)</li>
 <li>Vogt-Koyanagi-Harada disease (HLA-DR4)</li>
 </ul>
</ul>

Immunology

Ocular Immunology

Intro

FRCOphth Part 1 Study Notes

Orbit and ocular adnexae

Orbit

Extraocular Muscles

Orbital Blood Vessels

Paranasal Sinuses

Lacrimal Glands

Tear Film

Eyelids

Blinking

Anterior segment - ocular surface

Conjunctiva

Conjunctivitis

Sclera

Cornea

Corneal Structure And Development

Corneal Physiology

AC to Lens

Angle

Ciliary Body

Aqueous Humour Dynamics

Iris

Pupil

Lens

Posterior segment

Choroid

Vitreous

Retinal Macrostructure

Neurosensory Retina

Retinal Pigment Epithelium

Neuroanatomy

Venous Sinuses

Cerebral Ventricles

Cerebral Blood Supply

Supranuclear Gaze Pathways

Head And Neck Autonomic Nervous Supply

Head And Neck Glands

Osteology

Nerves

Muscles And Pharyngeal Arches

Extraocular Nerves

Sensory Nerves

Physiology

Physics Of Blood Flow

Neuronal Control Of Blood Vessels

Oxygen-Haemoglobin Dissociation Curve

Cytochrome p450

Pituitary Gland

Thyroid Hormone Production

Insulin

Glucagon

Parathyroid Hormone

Corticosteroids

Catecholamines

Cardiac Cycle

Renal Physiology

Fluid Balance

Acid-Base Balance

Muscle Physiology

Sensory Fibres

Cutaneous Receptors

Endocytosis

Glycosaminoglycans

Condensed Ocular Biochemistry

Eye Movements

Accomodation

Vision

Visual Cycle And Phototransuction

Visual Pathway

Visual Acuity

Colour Vision

Binocular Vision

Pathology

Collagen

Tissue Damage

Inflammation

Disease Entities

Wound Healing

Thrombosis / Atherosclerosis

Cell Growth

Neoplasia

Histopathology

Nystagmus

Free Radicals And Antioxidants

Microbiology

Viral Infections

Bacterial Infections

Fungal Infections

Protozoa

Nematodes

Antimicrobials

Genetics

Chromosomes

Mitosis

Meiosis

Genes

Polypeptide Synthesis

Histones

MicroRNA

Hardy-Weinberg Equilibrium

Mutations

Chromosome Defects

Autosomal Inheritance

X-Linked Inheritance

Mitochondrial Inheritance

Multifactorial Inheritance