Lesional elastase activity in psoriasis, contact dermatitis, and atopic dermatitis.

Human leukocyte elastase (HLE) is a broad spectrum serine protease derived from neutrophils and macrophages. We developed an assay to determine HLE activity on the skin surface in patients with inflammatory skin diseases. HLE activity was absent in the skin of healthy controls. A massive increase of HLE activity was found in lesional skin of psoriasis (31 times), allergic contact dermatitis (55 times), and atopic dermatitis (35 times), but not in uninvolved skin of diseased patients. Therefore, this assay appears to represent a useful biochemical marker of epidermal inflammation. The presence of proteolytically active HLE in diseased epidermis, which is known to contain specific inhibitors of this enzyme, suggests a pathophysiologic role of this enzymatic activity in psoriasis, contact dermatitis, and atopic dermatitis.