Relation between results of the simplified flow cytometric assays with those of more complex MRD assays. Bone marrow samples collected on day 19 of remission induction therapy from children with B-lineage ALL were examined for the presence of CD19⁺ cells coexpressing CD10 and/or CD34. Results were compared with those obtained with several sets of 4-antibody combinations in 376 patients (A), and with those of PCR amplification of immunoglobulin and T-cell receptor genes in 149 patients (B). Results of Spearman rank correlations are shown.