Granulocyte-macrophage colony-forming-unit (CFU-GM)-assays and/or liquid suspension cultures of bone marrow (BM) and peripheral blood (PB), using human placental conditioned medium as a source of colony-stimulating activity, were performed in 125 children with newly diagnosed acute lymphoblastic leukemia (ALL). Unlike the previous small series which invariably showed poor BM granulocyte-macrophage colony and cluster formations, we found 3 growth patterns. A poor-growth pattern was seen in 101 patients. A low-growth pattern with BM colony and cluster formations in the lower range of the normal limits was observed in 6 patients. All 6 patients had low-risk ALL, and the in vitro growth may reflect the residual normal CFU-GM in BM. Thirdly an over-growth pattern was noted in one patient with refractory ALL. In 49 cases where liquid suspension cultures of BM were performed, 4 had a normal-growth pattern and 42 had apoptotic cells and/or few residual granulocytic/monocytic cells after 7 days of culture. However, in both B cell ALL cases and in 1 refractory T cell ALL case with hyperleukocytosis, repetitive liquid suspension cultures of BM and PB consistently revealed an extensive growth of lymphoblasts. Thus, an over-growth pattern in either the BM CFU-GM assay or liquid suspension culture of BM or PB in children with ALL at diagnosis may indicate a refractory or aggressive disease. A low-growth pattern in the BM CFU-GM assay in children with ALL at diagnosis probably predicts a favorable outcome.
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