We proposed the hypothesis that pseudophakic inflammation, including the fibrin reaction, may be caused by cytokines and/or prostaglandins, synthesized by residual lens epithelial cells (LEC). To test our hypothesis, we measured IL-1 alpha, TNF-alpha, IL-6 and EGF in the culture media of human LEC, obtained by capsulotomy during cataract surgery, by ELISA. IL-1 alpha was detected in one of the two pools of 2-week cultures (20.7 pg/10(5) cells), in two of the three pools of 3-week cultures (12.0 pg/10(5) cells and 13.9 pg/10(5) cells), and in one pool of 4-week cultures (11.1 pg/10(5) cells). IL-6 was detected in 1-week culture (195 pg/10(5) cells) and in 7-week culture (81.6 pg/10(5) cells). TNF-alpha and EGF were not detected. During culture, the cells proliferated and underwent fibroblast-like changes on exposure to the plastic wells. IL-1 and IL-6 may be also produced in vivo by residual LEC contacting with posterior chamber lens after cataract surgery, and these mediators may play a role in postoperative inflammation including fibrin reaction.