Ploidy and Proliferative Activity of Human Brain Tumors

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Abstract
Ploidy and proliferative characteristics were estimated by flow cytometry of the nuclear DNA content of 92 human brain tumors. Samples were frozen at ––20°C immediately after surgery and single cell suspensions were obtained with a mechanical dissociation technique. Propidium iodide was employed for nuclear DNA staining. Human normal brain tissue was used as internal diploid reference standard. 86% of benign tumors had unimodal DNA distribution with a DNA index (DNA I = modal channel of the G0/1 peak of the studied population/modal channel of the G0/1 peak of the normal brain) usually within the diploid or near-diploid range. 14.0% had aneuploidy, with an additional cell peak having a median DNA I of 1.60. Among malignant tumors, these figures were 61.2 and 38.8% (p <0.001). The percentage of S phase cells was higher in malignant (median = 3.6) than in benign tumors (median = 2.0, p <0.01), without correlation to histological tumor subtype. Flow cytometry appears to be a useful method for evaluating differences in DNA distribution in tumors of the central nervous system.