We have previously reported that activated eosinophils enhanced the phosphatidylcholine (PC) secretion in type II pneumocytes. In this study, we have determined whether xanthine derivatives affect the PC secretion increased by activated eosinophils. Theophylline enhanced the increased PC secretion at 10(-5) M. 8-Phenyltheophylline dose-dependently enhanced the PC secretion. The enhanced secretion by either theophylline at 10(-5) M or 8-phenyltheophylline was suppressed by superoxide dismutase in combination with catalase. Pentoxifylline did not enhance the PC secretion increased by activated eosinophils, although it increased the PC secretion by itself. The PC secretion increased by theophylline at 10(-3) M or pentoxifylline was not suppressed by superoxide dismutase in combination with catalase. The present results suggest that xanthine derivatives increased the PC secretion in the co-culture of type II pneumocytes and activated eosinophils possibly through the inhibition of phosphodiesterases or the antagonism of adenosine receptors of the eosinophils.