Combination of SCF, IL-6, IL-3, and GM-CSF increases the mitotic index in short term bone marrow cultures from acute promyelocytic leukemia (APL) patients

Acute promyelocytic leukemia (APL) is characterized cytogenetically by the presence of a reciprocal translocation between chromosomes 15 and 17 [t(15;17)(q22–q24;q11–q21)] in the bone marrow cells in the majority of patients. Cytogenetic evaluation of bone marrow cultures from patients with APL is often technically difficult, due to frequent difficult marrow aspiration and the suboptimal quality of cytogenetic preparations. This has important implications for the cytogenetic detection of residual disease. This study examined the proliferative ability of the recombinant human growth factors—stem cell factor (SCF), interleukin-6 (IL-6), interleukin-3 (IL-3), and granulocyte macrophage-colony stimulating factor (GM-CSF)—to determine if they would provide a consistent improvement over the standard cytogenetic culturing techniques in terms of mitotic index (MI). In all cases, the MI of the growth factor stimulated cultures showed a considerably higher (3.5–198 fold) and statistically significant (p < 0.01) increase compared to the unstimulated cultures. We conclude that the use of recombinant human growth factors is potentially an effective way of increasing the MI in bone marrow cultures from APL patients for the purposes of diagnosis and residual disease detection.