Expression of Fas/Fas ligand and its relationship with apoptosis in retinoblastoma

Objective To investigate the correlation of expression of Fas/Fas ligand (FasL) and apoptosis in retinoblastoma (RB)． Methods The expression and distribution of Fas/FasL were detected by using immunohistochemical staining in 32 cases of RB． Light microscopy (32 cases), electron microscopy (4 cases) and TdT mediated biotin-dUTP nick-end labeling (TUNEL) (12 cases) were used to study apoptosis in RB． Results Apoptotic RB cells mostly located at RB regress area． Chromatin margination and apoptotic bodies were found in RB． TUNEL positive labeling cells especially located in tumor regress area． Positive immunolabeling for Fas and FasL was found in all RB specimens． There was a highly significant and positive correlation between the expression of Fas/FasL and apoptotic indices (AI) (P<0．01 or 0．001)． Conclusion The results suggest that apoptotic cell death is prevalent in RB and it may be one type of the most dominant cell death． Fas system may play an important role in oncogenesis and progression of RB, and the up-regulation of Fas system expression might induce RB cell apoptosis．