September 2002 Fellowships Grants and Awards

Corresponding author: Tel: +49 228 732337 Fax: +49 228 732408 E-mail: [email protected] BACKGROUND: Serum neopterin concentrations rise during activation of the cellular immune system. It is suggested that neopterin interacts with cellular redox mechanisms. This induces oxidative stress, which inhibits intracellular Ca transients in various cell types. In type II alveolar epithelial cells, Ca increase is considered involved in the exocytosis of surfactants. This exocytosis is disturbed during inflammation. Aims : To clarify whether neopterin affects adenosine triphosphate (ATP)-induced Ca transients in an alveolar epithelial cell line (L2). Methods : Ca transients were detected as fura-2 fluorescence by an image analysis system. Results : Cells were exposed for 100 sec to ATP (1 m M, repeated four times). The first application of ATP induced an increase of the fluorescence ratio by approximately 100%, while the following stimulations resulted in smaller transients. In a second set of experiments, L2 cells were exposed to ATP or ATP + neopterin (100 nM), alternately. Simultaneous application of neopterin inhibited Ca transients almost completely. Conclusions : Inhibition of Ca transients by neopterin may lead to suppressed exocytosis of surfactant proteins in alveolar epithelial cells. This might contribute to the deterioration of pulmonary functions in the course of inflammatory processes.