Ocular Immunology - Eye Notes

Unlock FRCOphth Part 1 Study Notes to access this content.

Mucosa associated lymphoid tissues (MALT)

Mucosa is more easily breached than skin and so considerable lymphoid tissue is concentrated within the mucosa to deal with new antigens

Found in GI, respiratory, and GU tracts, conjunctiva (conjunctival associated lymphoid tissue) and glands of the ocular adnexa
Comprises:

Recirculating IgA-producing B cells and T cells express homing receptors for addressins on endothelial cells of vessels supplying mucosal surfaces
Addressins essentially direct movement of cells to various mucosal sites
Memory T cells have ‘first call’ on invading pathogens

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

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

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

Hot Topic

Immune privilege in the AC

Immunological response to antigen entering the AC: systemic suppression of potentially damaging cell-mediated and humoral responses that might damage ocular tissue.
Occurs within 1 week of introduction of antigen to the AC
APCs process antigen
Suppressor T cells develop which inhibit T-helper cells
Normal cytotoxic T cell responses to antigen (T cells can still lyse target cells)
Normal systemic antibody production to the antigen
Requires an intact spleen
Mediated by TGF-beta and other cytokines

Protects ocular structures from potentially damaging immune-mediated inflammation
Components