Serum levels of soluble intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and interleukin-2 receptor in patients with vernal keratoconjunctivitis and allergic conjunctivitis

Epithelial cells in ocular allergy

Conjunctival epithelial cells do not act only as mechanical barriers, preventing the entry of particles, bacteria, viruses, and noxious substances into the eye but they are also active participants in the regulation of allergic inflammation via expressing adhesion/effector molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, human leukocyte antigen-DR, CD40/CD40L, Fas/Fas ligand) on their surfaces and releasing numerous proinflammatory cytokines, such as eotaxin, regulated on activation normal T-cell expressed and released (RANTES), macrophage inflammatory protein-1, interleukin (IL)-8, IL-6, and tumor necrosis factor-a, which are necessary for the proliferation, differentiation, activation, and chemotaxis of various inflammatory cells into the conjunctiva. Histamine, released from the conjunctival mast cells, might stimulate the synthesis of proinflammatory molecules such as IL-6 and IL-8 by the epithelial cells through the receptors that couple to inositol phosphate generation and, therefore, amplify the allergic response. The relationship between the epithelium and allergy should be considered in detail in future studies aiming at an effective control and treatment of all forms of allergic conjunctivitis.

Allergic and immunologic disorders of the eye. Part II: ocular allergy

Allergy affects more than 15% of the world population, and some studies have shown that up 30% of the US population has some form of allergy. Most of these patients have various target organs for their allergies, and most have ocular involvement. The ocular component may be the most prominent and sometimes disabling feature of their allergy. Some are affected for only a few weeks to months, whereas others have symptoms that last throughout the year. The seasonal forms may present to clinical allergists, whereas the more chronic forms may present to ophthalmologists. Thus, in the second of this 2-part review series (Part I: Ocular Immunology appeared in the November issue of the Journal), an overview is provided of the spectrum of ocular allergy that ranges from acute seasonal allergic conjunctivitis to chronic variants of atopic keratoconjunctivitis. With a better understanding of the immunologic mechanisms, we now can develop better treatment approaches and design further research in intervention of allergic eye diseases.