Contact dermatitis pathophysiology

Although there are five types of hypersensitivity responses, two of these, types 1 and 1 play a significant role in the pathophysiology of allergic eye disease. The ocular manifestations include seasonal allergic conjunctivitis (SAC), giant papillary conjunctivitis (GPC), vernal keratoconjunctivitis (VKC), atopic keratoconjunctivitis, contact dermatitis, and urticaria. These are discussed in Chapter 27. 

The most frequent manifestations of drug allergy involve the skin. Urticaria, angioedema, exanthematous skin rashes, allergic eczematous contact dermatitis, photodermatitis, fixed drug eruptions, erythema multiforme, and the Stevens-Johnson and Lyell syndromes are the best characterized clinical manifestations. Their clinical aspects, evolution, and pathophysiological mechanisms are described in detail in the following chapter. 

Gaspari AA (1997) The role of keratinocytes in the pathophysiology of contact dermatitis. Immunol Allergy Clin North Am... 

The pathophysiologic mechanisms involved in PACD have been extensively studied. These studies routinely revealed that the immunologic process involved in this reaction is analogous to the process occurring in plain allergic contact dermatitis to a nonphotosensitized antigen. The mechanism involved in the production of the photoantigen is less clearly defined. 

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