Monitoring of MRD with anti-CD58 labeling.

Bone marrow cells from 2 children with B-lineage ALL were studied at diagnosis (left panels) and at the end of remission-induction therapy (right panels), when both patients were in complete morphologic remission. Flow cytometric dot plots illustrate the expression of CD34 and CD58 on CD19⁺ cells. In both patients, most CD19⁺ cells at diagnosis were CD34⁺ and CD58⁺. At the end of remission induction, CD19⁺CD34⁺CD58⁺ cells represented less than 0.01% of bone marrow mononuclear cells in one patient (top). In the other patient (bottom), 0.2% of cells expressed this phenotype, indicative of MRD. PCR amplification of Ig genes confirmed these findings (less than 0.01% and 0.4% MRD, respectively).