Detection of minimal residual disease in childhood acute lymphoblastic leukaemia using fluorescence in‐situ hybridization

Abstract

Using centromere-specific probes and a fluorescence in-situ hybridization (FISH) technique in cases of childhood hyperdiploid acute lymphoblastic leukaemia (ALL), cells with extra copies of chromosomes can be differentiated from normal cells by their extra signals in both metaphase and interphase nuclei. In this way the entire cell population, not only those cells in division, can be analysed, thereby providing a valuable technique not only for determining leukaemia cell karyotype at diagnosis but also for the detection of minimal residual disease (MRD). We have conducted 161 analyses of remission bone marrow aspirates (BMs) in 13 children with hyperdiploid ALL. Slides were analysed blind and in parallel to 35 control samples. Control BMs showed very low numbers of trisomic cells (mean +/- 2 x SD = 0.13 +/- 0.34%). MRD was detected in 5/13 cases of ALL investigated while on chemotherapy. One out of five newly diagnosed cases and all three relapse cases of ALL had significantly raised levels of hyperdiploid cells in day 28 BMs. The presence of detectable disease in day 28 BMs suggests the need for larger studies to find whether this data is of prognostic value.

Acquired X-chromosome aneuploidy in children with acute lymphoblastic leukemia

“…In- terphase FISH is one of the sensitive techniques particularly suitable for studying cases with an HH karyotype [15,16]. In our study, remission was confirmed by FISH in all 12 patients studied.…”

“…This technique is especially useful in childhood ALL, which is characterized by nonrandom gains of whole chromosomes, leading to hyperdiploidy [11][12][13]. In addition, it has been proposed to detect minimal residual disease (MRD) [14][15][16][17].…”

Detection of residual aneuploid leukemic cells by “Continuous Gating”

“…Aberrant density of surface markers on leukemic cells can be found for several markers like CD45 or CD34 (5). Beside aberrant combinations of surface markers, density measurements of antigens on leukemic cells can be helpful in the detection of minimal residual disease (3,6,7). The surface marker expression can be used to create an ''area of interest'' in the dot-plot derived by flow cytometric measurement where the malignant cells can be found.…”