Apoptosis detection in histological section is very important, but usual methods (TUNEL and morphologic changes) are controversial. Immunohistochemical stains of activated proteins during apoptosis improve detection of cell death in tissue sections. Activated caspase-3 and cleaved cytokeratin-18 are more and more used.
Objective: This study compared immunohistochemical markers (activated caspase-3, cleaved cytokeratin-18 and two antibodies not yet evaluated: activated caspase-7 and cleaved PARP-1), cellular morphology and TUNEL.
Material and methods: Tumour xenografts of the human colon cancer cell line HT29 were used, treated by photodynamic therapy, to obtain large numbers of cells undergoing apoptosis. Apoptotic cells were quantified and apoptotic indices were determined for each marker.
Results: Comparison of apoptosis index indicated statistically best sensibility with activated-caspase-3 and cleaved-cytokeratin-19.
Conclusion: Immunohistochemistry for activated caspase-3 and cleaved cytkeratin-18 appear to be an easy, sensitive, and reliable method for detecting and quantifying apoptosis in this model. There are therefore recommended for the detection and quantification of apoptosis in tissue sections. Other markers as cleaved PARP-1 and activated caspase-7 can be an interessant solution: advantages and inconvenience for each methods are exposed.