Unconjugated pteridines in bronchoalveolar lavage as indicators of alveolar macrophage activation.

Bronchoalveolar lavage (BAL) has shown great efficacy in clarifying the role of immune processes in many disorders of the lower respiratory tract. Following the in vitro demonstration that neopterin is an indicator of the activation of macrophages, neopterin was measured in the BAL fluid and cells from patients with various pulmonary diseases. In most of the patients, high levels of neopterin were found in the serum, BAL fluid and BAL cells. Because neopterin in BAL fluid results from local production as well as from plasma transudation, neopterin in BAL cells seems to reflect the macrophage stimulation more directly. In addition, the correlation between cellular neopterin and lymphocyte count was found to be more significant than the correlation between cellular neopterin and macrophage count. Neopterin in BAL fluid and cells may be a useful measurement in the investigation and elucidation of pulmonary pathologies involving the cellular immune system.