engleski

Subpopulations of B-cells in bone marrow of children with acute lymphoblastic leukaemia (ALL) treated by protocol BFM-95

It has been hypothesised that the persistence of residual leukaemic cells may induce abnormalities of B-cell compartment in bone marrow (BM) and that these abnormalities could be used as criteria to predict relapse in B-precursor ALL patients in cytomorphologic remission (Ciudad et al, 1999). In order to verify this hypothesis we first analysed precursor and mature B-cell subpopulations in bone marrow of patients with B-lineage ALL during treatment by protocol BFM-95. Control BM samples were obtained from children with suspected but not diagnosed haematological malignancies and from healthy donors of allogeneic BM for allo-BMT. The BM samples were obtained at diagnosis, at control BM evaluations as scheduled by BFM-95, and at suspected relapse of the disease. Here we present our preliminary data on the relative contributions of the six CD19+ BM cells defined by expression of CD10, CD20 or CD34 (triple antibody combinations) and also evaluate alterations in the overall B-cell differentiation pathway. The data obtained show a general trend towards B-cell subset changes during the treatment of B-precursor ALL: a decrease in immature B-cells during induction, followed by an increase above control values before consolidation and subsequent normalisation of B-cell subset proportion after consolidation. The inverse situation was observed for more mature B-cell subsets. The cut-off control values for immature BM CD19+CD34+ and CD19+CD20- subsets in our study were higher than reported in literature, probably due to different patient selection (children + adults) in original study. Accordingly, the proportion of ALL with an increased percentage of immature CD19+ cells during remission was lower than in the original study. In a proportion of children with B-precursor ALL before and after consolidation, the percentage of more immature B-cells was far above cut-off limits: the aim of the ongoing study is to link these abnormalities in B-subsets to clinical behaviour of ALL.

B-cells; ALL; children

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