Katzilakis N et al. (2004) Spectral characteristics of acute lymphoblastic leukemia in childhood. Leuk Res 28: 1159–1164

It is difficult to distinguish normal lymphocytes from acute lymphoblastic leukemia (ALL) cells using light microscopy. Diagnosis of this relatively common childhood malignancy, therefore, relies on immunologic, molecular and cytogenetic assessments. A new study by Katzilakis et al. investigates spectral imaging as an additional method.

Bone marrow smears taken from 15 children with ALL and 15 children with normal bone marrow were stained using the May-Grunwald-Giemsa method. A population of 300 cells from each smear was then studied using a spectral microscope system. Briefly, this involved the automated scanning of each sample across a range of wavelengths to produce a set of absorbance spectra. Results from ALL cells (lymphoblasts) and normal bone marrow cells (lymphocytes) were then compared.

The spectra produced from the two cell types were similar: absorbance peaks were at 535 nm for lymphocytes and 545 nm for lymphoblasts. The mean absorbance of the lymphocytes, however, was higher than that of the lymphoblasts throughout the spectral range. This difference was maximal at 630 nm. By comparing the difference in absorbance at 545 nm and 630 nm for each cell, the authors were able to demonstrate statistically significant differences between the spectra of normal lymphocytes and lymphoblasts (P < 0.0001).

In summary, it was possible to differentiate between ALL and normal bone marrow cells using spectral imaging. This method may prove useful in the diagnosis of ALL and in assessing relapse of the disease.