Detection of residual disease by flow cytometry on day 19 of remission-induction therapy.
Bone marrow samples were obtained on day 19 from 6 patients with newly diagnosed ALL. All 6 samples lacked leukemic cells identifiable by morphologic analysis. Dot plots at left show flow cytometric results illustrating expression of TdT (x-axes) and CD5 (y-axes) on gated CD5+, HLA-Dr−, CD19−, CD33− lymphoid cells in 2 patients with T-lineage ALL. Dot plots at middle and right illustrate expression of CD10 (y-axes) and CD66c (x-axes; middle panels) or CD45 (x-axes; right panels) on gated CD19+ lymphoid cells in 4 patients with B-lineage ALL. Dashed areas in all plots correspond to areas that appear empty when normal bone marrow samples are analyzed. In 3 patients (top panels), residual leukemia was present at the percentages indicated; in the other 3 (bottom panels), leukemic cells were undetectable. More than 105 cells were analyzed in each sample.
