Flow cytometric analysis of human acute leukemia samples by using the MoAbs HSL11, HSL96, and HSL2. Frozen samples of childhood acute leukemia were thawed and stained in the cytoplasm (in a few cases on the cell surface as well) by the MoAbs specific to λ5, VpreB, pre-BCR, μH chain, κL chain, λL chain, CD19, CD22, or CD79b in the same way as in Fig 2. Staining profiles with these MoAbs (thick solid line) and staining profiles with an isotype-matched control MoAb (thin dotted line) are overlaid in the histograms. Though data are not shown, the T-ALL sample was positive for CD3, CD4, and CD8 whereas the AML sample was positive for CD13 and CD33. All data including other leukemia samples are summarized in Tables 2 and 3. Sources of leukemia samples: BM, bone marrow; PB, peripheral blood; LN, lymph node; PE, pleural effusion.