Usefulness of different thresholds used to discriminate ALL and AML according to the negative control. A. Isotype control used as negative control. % of cells showing fluorescence above that of the negative control with a 1% cut-off (40 AML1 and 96 ALL). Three thresholds are shown: EGIL 10%* EGIL, 3%** and ROC-established 13%. B. Residual lymphocytes used as negative control. % of cells showing fluorescence above that of the negative control with a 1% cut-off (75 AML1 and 128 ALL). Three thresholds are shown: EGIL 10%*, 3%** and ROC-established 28%. * (Béné et al, 1995); **(Peffault de Latour, 2003).