Thy-1 expression on blast cells from adult patients with acute myeloid leukemia.

Bone marrow and peripheral blood from 28 adult patients with acute myeloid leukemia (AML) were analyzed for the surface expression of the Thy-1 antigen by dual-colour flow cytometry. The Thy-1 antigen was expressed on greater than 5% of cells from seven patients with the proportions of Thy-1 positive cells ranging from 8.1% to 85.0%. The CD34+ Thy-1+ phenotype was present in all seven cases. The expression of Thy-1 on leukemia cells from patients with AML may need to be considered in the development of methods of normal stem cell isolation from these patients.