Comparative image and flow cytometric TUNEL analysis of fine needle samples of breast carcinoma

The assessment of apoptosis in solid tumors is of interest because of its b iological role in tumor evolution and response to therapy. A commonly used method for apoptosis measurement is the TUNEL 3 ' end-labeling technique, w hich has shown wide variations in results when applied to solid tumors. Thi rty-one fine needle breast carcinoma samples were analyzed by fluorescent T UNEL assay and DNA content using image analysis and flow cytometry, TUNEL p ositivity, seen both in cells with apoptotic morphology and in a subset of morphologically normal cells, was categorized into five staining patterns a nd quantitated. Values for patterns of TUNEL-positive cells were compared w ith TUNEL positivity measured by flow cytometry, Flow cytometric quantitati on showed a mean of 24.3% positive cells, which correlated (P < 0.02) with total positive cells (all patterns) measured by image (22,4%), Image analys is quantitation of morphologically apoptotic cells (4.2%) did not correlate with flow cytometric TUNEL positivity and the majority of TUNEL-stained ce lls were morphologically normal (17%), Image analysis allows discrimination of TUNEL-positive morphologically apoptotic and nonapoptotic cells, which are included in the total number of TUNEL-positive events measured by flow cytometry. (C) 2001 Wiley-Liss, Inc.