Elevated serum levels of lysozyme in desquamative interstitial pneumonia.

We present a case of desquamative interstitial pneumonia (DIP) with elevated serum levels of angiotensin-converting enzyme and lysozyme, which are often found in sarcoidosis. After steroid therapy, improvements in the lung opacity and the serum lysozyme level were observed. Retrospective evaluation of four additional DIP cases showed that four of the five cases studied had an elevated serum lysozyme level. In an immunohistochemical analysis of the lung specimens, increased expression of lysozyme were found in the neutrophils and the alveolar macrophages. Elevated levels of serum lysozyme can occur in diseases such as DIP in which the neutrophil and macrophage activity may affect a patient's pathological condition.