Analysis of leukemic cell activity with a simple acridine orange staining method.

Leukemic cells from 28 patients with acute lymphoblastic leukemia (ALL) were supravitally stained with acridine orange (AO). Based on the staining characteristics of their cells, the patients were divided into an orange cell-dominant group (15 patients) and a green cell-dominant group (13 patients). The prognosis was better in the former than in the latter group. Orange cells which had high RNA contents were observed, while the proportion of dividing cells was high. Supravital staining with AO is a very simple and useful method for assessing the metabolic activity of leukemic cells in ALL; this method may thus be useful in assessing the prognosis of these patients.