Value of colony forming unit-granulocyte macrophage assay in predicting relapse in acute myeloid leukaemia

The influence of fullerenol on the cell number, cell area and colony forming unit ability in irradiated human erythroleukemic cell line

DET (dye exclusion test) cell count and cell area by computer analysis of the images were determined in cell lines of human eritroleukemia (K562), which were irradiated with X-rays in one dose of 24 Gy and pretreated with 10 nmol/mL fullerenol (Cgo(OH)24). Cell samples obtained using a citocentrifuge and May-Gr?nvald Giemsi (MGG) during, were analyzed. The cell colony formation ability was monitored using quantative CFU (colony forming unit) test. Irradiation decreases the number of K562 cells, but fullerenol significantly increases cell number on 24th and 48th hour of the experiment. Cell area is larger, and the number of formed cell colonies after irradiation is significantly smaller compared to pretreated groups during the whole experiment. Pretreatment with fullerenol maintains a smaller cell area, and the number of colony formed units was larger compared to the irradiated cells.

In vitro growth in acute myeloblastic leukemia: clinico-biological correlations

In the present review we analyse the current knowledge about the growth properties of AML progenitor cells and their relationship with other clinico-biological characteristics of the disease. Leukaemic colony forming unit L-CFU is considered to be the clonogenic cell in AML and more immature than the blast cell population. Our studies have shown that in leukaemic hematopoiesis colony forming cells can exist among both cell fractions CD34+ and CD34-. Optimal "in vitro" proliferation of L-CFU is dependent upon the addition of exogenous growth factors. However, it has been observed that leukaemic progenitor cells frequently display a certain degree of autonomous proliferation. In order to quantify the "in vitro" behaviour of L-CFU, we have explored 3 parameters: 1) plating efficiency (PE); 2) autonomous growth (AG); and 3) autonomous proliferative index (API) which was calculated as AG divided by PE and we have correlated them with other clinico-biological data. According to the FAB classification we could observe that patients with M3 subtype showed an higher PE than other AML subgroups and a significantly lower API. Regarding CD34 expression we observed that AG was enhanced in CD34+ cases and also in those showing a higher rh123 elimination. In order to determine whether PE could condition clinical evolution, we analysed this parameter in a large series of patients but failed to demonstrate any relationship. By contrast, we observed that patients who displayed a higher API showed a shorter survival than patients with lower API (18% vs 48% surviving at 3 years). We have also shown that abnormalities in the CFU-GM growth pattern could be associated with risk the of relapse in AML patients; a switch from normal to abnormal "in vitro" growth should alert us. But for the assessment of the real value of these analyses sequential follow-up studies are mandatory. In summary, cell culture studies contribute not only to a better understanding of leukaemic hematopoiesis but may also contribute to better disease monitoring.

Detection of abnormalities in B-cell differentiation pattern is a useful tool to predict relapse in precursor-B-ALL

Immunophenotypic investigation of minimal residual disease (MRD) has traditionally been based on the investigation of phenotypic aberrants at diagnosis to be used later as a target for MRD detection. This approach has several shortcomings (it is only applicable to patients with aberrant phenotypes, requires a diagnostic sample, and is patient-specific) and therefore a search for simpler alternatives is warranted. The present study is based on the hypothesis that in precursor-B-ALL patients the persistence of residual leukaemic cells may induce abnormalities in the precursor-B-cell compartment in bone marrow (BM) and these could be used as a criteria to predict relapse. These abnormalities may include: (1) the presence of an increase in the frequencies of immature B cells (CD34+/CD19+ or CD20-/CD19+) or (2) the existence of an altered B-cell differentiation pathway due to a blockade or to the presence of B cells outside the normal pathway. A total of 180 BM samples from 45 consecutive precursor-B-ALL patients who achieved morphological complete remission (CR) were analysed by multiparametric flow cytometry. Our results show that a significant increase in immature B-cell subsets or an altered B-cell differentiation predicts a high relapse rate (P<0.01) and a shorter disease-free survival (P<0.01). Moreover, abnormalities in either of these two criteria detected at specific time points during follow-up (end of induction, maintenance, or after treatment) were associated with a significantly shorter disease-free survival (P<0.01). In summary, the investigation of abnormalities in B-cell differentiation is a relatively simple and cheap approach for predicting relapse in precursor-B-ALL patients.