SCE frequency and lymphocyte proliferation in a Down's syndrome mosaic developing an acute lymphoblastic leukemia

Sister chromatid exchange and cell proliferation time were examined by differential chromatid staining in a Down's syndrome, mosaic case suffering from acute lymphoblastic leukemia. The SCE frequency in stimulated blood lymphocytes had already increased before treatment was started. The therapy was correlated with a further SCE increase in the trisomic cells but not in the normal ones. The trisomic cells showed a shortened cell cycle time in the remission phase, as well as during therapy. In both cell lines, a very similar slow down in cell proliferation was observed after treatment, as indicated by a high number of mitoses from the first and second mitotic cycle. The results indicate that the trisomic cells are more sensitive to the mutagenic effect of the antileukemic treatment than are normal cells.