Investigation of karyotypic, morphologic and clinical features in patients with acute myeloid leukemia blast cells expressing the neural cell adhesion molecule (CD56).

The mechanisms of extramedullary leukemic infiltration are not well characterized. The cell-surface glycoprotein CD56, which is identical to the neural cell adhesion molecule, may be involved. Using the Leu-19 antibody and flow cytometric methods, the leukemic blasts of 22% (70 of 314) of patients were CD56 positive. This was most common in acute monocytic leukemia (15 of 18, 83%) and in patients with the cytogenetic abnormalities t(8;21) (seven of 13, 54%) and trisomy 8 (nine of 22, 41%). CD56 expression was not associated with extramedullary leukemic infiltration, but was correlated with positivity for CD11b (p < 0.001), CD14 (p < 0.001) and CD19 (p = 0.018). Although associated with morphologic and cytogenetic features, CD56 expression alone cannot account for most instances of tissue infiltration in acute myeloid leukemia (AML).