The immunologic basis of patch testing.

During the past decade much has been learned about the cell-mediated immune responses that result in allergic contact dermatitis. The complex interaction between the hapten, the Langerhans cell, the specifically sensitized T cell, and the various soluble mediators of cellular immunity have begun to be delineated. This article reviews the pathophysiology of allergic contact dermatitis. Clinical and physicochemical modulators of this response, such as patient age, the anatomic site of antigenic challenge, and prior treatment with UVB, PUVA, glucocorticoids, or cyclosporine (Cyclosporin A), are stressed. The implications of these findings to the techniques of patch testing are summarized.