Ligation of CD38 induces apoptosis in AML cells.

Leukemic myeloblasts (patient 3 in Table 1) were cultured for 48 hours on allogeneic bone marrow stromal layers in the presence of anti-CD38 (T16) or of a control nonreactive Ig. Top panels are flow cytometric contour plots illustrating staining with Annexin-V (x-axis; a marker of apoptosis) and propidium iodide (PI, y-axis; a marker of cell membrane permeability) after culture. Bottom panels illustrate DNA content analysis; a marked increase in hypodiploid (< 2N) cells, characteristic of apoptosis, is seen in cultures containing anti-CD38. Among the viable cells, the percentage of cells in G₀/G₁, S, and G₂/M was 90%, 8%, and 2% with control Ig, and 95%, 4%, and 1% with anti-CD38, respectively.