Protein Contact Dermatitis: Allergens, Pathogenesis, and Management
Cheryl Levin; Erin Warshaw

Abstract
Protein contact dermatitis is an allergic skin reaction induced principally by proteins of either animal or plant origin. The clinical presentation is that of a chronic dermatitis, and it is often difficult to differentiate between allergic contact dermatitis and other eczematous dermatoses. One distinguishing clinical feature is that acute flares of pruritus, urticaria, edema, or vesiculation are noted minutes after contact with the causative substances. Additionally, the patch-test result is typically negative, and the scratch- or prick-test result is positive. The pathogenesis of protein contact dermatitis is unclear but may involve a type I (immunoglobulin E, immediate) hypersensitivity reaction, type IV (cell-mediated delayed) hypersensitivity reaction, and/or a delayed reaction due to IgE-bearing Langerhans' cells. Management involves avoidance of the allergen.


Introduction
The term "protein contact dermatitis" was coined by Hjorth and Roed-Petersen in 1976 to describe the condition of several food handlers with hand and forearm eczema. The responsible allergen in these patients was not a low-molecular-weight substance, as in classic allergic contact allergy, but a protein of greater molecular weight. Additionally, these patients had positive scratch-test results and (in some cases) specific immunoglobulin E (IgE) antibodies to the food they handled, which included meat, fish, cheese, vegetables, and spices, whereas patch-test results were often negative. Of 33 patients evaluated, only 6 exhibited delayed hypersensitivity; in 10 patients, scratch tests revealed the only explanation for their eczema. Most patients did not have respiratory or mucosal symptoms. The authors postulated that protein contact dermatitis was a combined type I- and type IV-mediated allergic reaction to "proteins."

In 1983, Veien and colleagues further characterized protein contact dermatitis. They defined specific criteria, including (1) a chronic recurrent dermatitis caused by contact with proteinaceous material, (2) an acute urticarial or vesicular eruption occurring minutes after contact with the causative protein, (3) immediate testing results that are usually positive, and (4) patch-test results that are often negative.

Because there is an immediate wheal and flare response, some authors have classified protein contact dermatitis as part of the "contact urticaria syndrome," a term that encompasses immunologic, nonimmunologic, and uncertain mechanismmediated contact urticaria. In this view, protein contact dermatitis is not a unique entity and may be caused by both nonimmunologic (irritant) and immunologic (allergic) mechanisms. This article will refer to protein contact dermatitis as that which is immunologically mediated. Because protein contact dermatitis is relatively rare, little is known about its epidemiology. Information from case series
indicates that protein contact dermatitis is primarily seen in chefs, veterinarians, dairy workers, and workers in other occupations in which there is significant protein exposure. The purpose of this review is to summarize the current literature on the clinical presentation, pathogenesis, and management of protein contact dermatitis.

DOWNLOAD COMPLETE PDF HERE

0 comments