Immunologic aspects of atopic dermatitis.

The immunology of atopic dermatitis is complex, multilayered, and multifaceted. In one realm are the IgE-mediated, type I hypersensitivity reactions that can be elicited in at least 80% of patients. A second realm is that associated with cell-mediated immunity and delayed-type hypersensitivity (type IV) reactions. Scattered between these immunologic paradigms are the various splinters: immune complex abnormalities, putative late-phase reactions, and cutaneous basophil hypersensitivity. The inflammatory lesion of atopic dermatitis probably is a composite of the many model reactions that investigators have glimpsed but never resolved into a reasonable concept.