Immunopathogenesis of ocular allergy: a schematic approach to different clinical entities.
OBJECTIVE
The immunopathogenesis of ocular allergic disorders is generally related to the specific immunoglobulin E-mediated mast cell activation and the following cascade of inflammatory mediators. Seasonal and perennial allergic conjunctivitis, however, are the only ocular diseases to involve solely type I hypersensitivity. The other main forms, vernal and atopic keratoconjunctivitis, have a more complex immunological basis and a chronic inflammatory component. Involvement of inflammatory cells, particularly eosinophils and T cells, cytokines and proteases can lead to more serious corneal damage with vision-threatening potential.


RESULTS
Experimental allergic conjunctival models and clinical research studies have shown that T helper type 2-related mechanisms are definitely involved in the sensitization phase of ocular allergy, however, both T helper type 1 and type 2 cytokines are overexpressed in the active disease, contributing to the development of ocular inflammation.


CONCLUSIONS
A review of the recent literature allows us to better understand the mechanisms involved in the development of ocular allergy and to guide us toward a more schematic approach, which could possibly be useful in forming a new classification, standardizing clinical phases and individuating new treatment targets.
Leonardi
Andrea
A
Ophthalmology Unit, Department of Neuroscience, University of Padua, Italy. andrea.leonardi@unipd.it
De Dominicis
Chiara
C
Motterle
Laura
L
D000818:Animals; D003233:Conjunctivitis, Allergic / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D016207:Cytokines / Q000276:immunology* / Q000378:metabolism; D004804:Eosinophils / Q000276:immunology / Q000378:metabolism; D005123:Eye / Q000276:immunology; D006801:Humans; D007073:Immunoglobulin E / Q000276:immunology*; D018836:Inflammation Mediators / Q000276:immunology / Q000378:metabolism; D007637:Keratoconjunctivitis / Q000276:immunology / Q000378:metabolism / Q000503:physiopathology; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000378:metabolism
D016207:Cytokines; D018836:Inflammation Mediators; D007073:Immunoglobulin E