Biochemical Abnormalities:

Scientists suspect that changes in the skin's protective barrier make people with atopic dermatitis more sensitive to irritants. Such people have lower levels of fatty acids (substances that provide moisture and elasticity) in their skin, which causes dryness and reduces the skin's ability to control inflammation.

Other research points to a possible defect in a type of white blood cell called a monocyte. In people with atopic dermatitis, monocytes appear to play a role in the decreased production of an immune system hormone called interferon gamma (IFN-γ), which helps regulate allergic reactions. This defect may cause exaggerated immune and inflammatory responses in the blood and tissues of people with atopic dermatitis.

Faulty Regulation of Immunoglobulin E (IgE):

As already described in the section on diagnosis, IgE is a type of antibody that controls the immune system's allergic response. An antibody is a special protein produced by the immune system that recognizes and helps fight and destroy viruses, bacteria, and other foreign substances that invade the body. Normally, IgE is present in very small amounts, but levels are high in 80 to 90 percent of people with atopic dermatitis.