INTERCOMPARISON OF APOPTOSIS MORPHOLOGY WITH ACTIVE DNA CLEAVAGE ON SINGLE CELLS IN-VITRO AND ON TESTIS TUMORS

Apoptosis morphology (DNA condensation) and endonucleolytical DNA clea vage (TdT assay) were measured simultaneously on double fluorescence l abelled cells employing confocal laser scanning and conventional immun ofluorescence microscopy, lit vitro experiments on irradiated HL-60 ce lls revealed a high correspondence of non-apoptotic (normal) cells wit hout detectable DIVA cleavage, versus apoptotic cells and apoptotic bo dies shelving DNA cleavage. Experiments performed on histological slid es of testis tumours reflected a heterogeneous picture: non-apoptotic (normal) cells, apoptotic cells, and apoptotic bodies appeared either with or without detectable DNA cleavage. These data allowed the charac terization and quantitation of the grade of disturbance/heterogeneity of the apoptosis programme in vivo. Furthermore, the measured apoptoti c index (AI) based on apoptosis morphology was lower than the AI asses sed by DNA cleavage, in contrast to published work. Taken together, th ese methods represent a new approach and might be suitable for improve d correlation with clinical parameters. In addition, the data presente d confirm frequently published doubts regarding the ability of the TdT assay to detect apoptosis as defined by morphological criteria in tum ours. (C) 1998 John Wiley & Sons, Ltd.