Elevated serum chymotrypsin levels in a patient with junctional epidermolysis bullosa. Normalization after UVB therapy with good clinical response.

A 36-year-old Hispanic woman, covered with blisters since birth, was found to have markedly elevated chymotrypsin levels in her serum. This proteolytic enzyme is thought to digest laminin, thus causing separation of the basement membrane at the level of the lamina lucida, corroborating findings on electron microscopy. On the basis that the sun-exposed areas of the skin were relatively less involved, she received a course of UVB therapy, with total clinical clearance of her lesions after 3 weeks. A repeat estimation of serum chymotrypsin at this time revealed normal levels of this enzyme. It is thought that the elevated chymotrypsin levels were either released from the Langerhans cells themselves or from lymphocytes or keratinocytes as a result of Langerhans cell activity, and that the suppression of Langerhans cell activity by UVB inhibited the release of this proteolytic enzyme, resulting in the suppression of blister formation in our patient.