Flow cytometric detection of residual disease in acute leukemia by assaying blasts co-expressing myeloid and lymphatic antigens.

A method employing CD45-gating of blast cells was evaluated for the flow cytometric detection of residual disease in CD19- and myeloid antigen-positive acute leukemia in morphologic remission. In the normal bone marrow, CD45-gating identified at least three populations of immature cells, one of which appeared to retain a minute fraction of CD19- and CD13/33-antigen co-expressing cells. In acute leukemia, CD45 expression separated the blast cell population from the normal marrow cell populations. In the majority of patients with CD19- and myeloid antigen-positive acute leukemia, subpopulations of blast cells with this mixed phenotype were detected during morphologic remission.