[Distribution of antigenic aberration in the bone marrow of acute leukemia in complete remission]

The aberrant, leukemia-associated antigen expression patterns allow us to discriminate leukemic blasts from normal precursor cells. Our major goal was to determine a guideline for the detection of minimal residual disease using CD20+/CD34+ and myeloid Ag+/CD19+ combination in the bone marrow of acute leukemia in complete remission (CR) after chemotherapy.

Bone marrow samples from 117 patients with acute leukemia in complete remission after chemotherapy and from 22 healthy controls were immunophenotyped by triple staining and measured by flow cytometry.

The CD20+/CD34+ cells in the large lymphocyte gate (R1) ranged from 0% to 3.% (0.8plusmn;0.82%, P=0.000) in CD20+/CD34+ B-lineage ALL CR (N=31), from 0.03% to 4.2% (0.7plusmn;0.83%, P=0.000) in CD20-/CD34- B-lineage ALL CR (N=66), from 0.1% to 0.96% (0.45plusmn;0.32%, P=0.016) in T-ALL CR (N=10), and from 0.02% to 0.48% (0.18plusmn;0.15%, P=0.776) in AML CR (N=10). The CD13,33+/CD19+ cells in R1 gate ranged from 0% to 2.69% (0.37plusmn;0.48%, P<0.001) in CD13,33+/CD19+ B-lineage ALL CR (N=31), from 0% to 1.8% (0.31plusmn;0.28%, P<0.001) in CD13,33-/CD19+B-lineage ALL CR (N=65), from 0.02% to 0.64% (0.29plusmn;0.22%, P=0.071) in T-ALL CR (N=9), and from 0% to 0.17% (0.07plusmn;0.09%, P=0.341) in AML CR (N=3).

Using an immunophenotypic method for the detection of early relapse or minimal residual disease of B-lineage ALL bone marrow in CR after chemotherapy, different cutoff values should be applied according to antigen combination and gating. When the proportion of aberrant antigen combination was less than 5% in large lymphocyte gate, the results should be interpreted with caution.