Abstract
One characteristic of Philadelphia chromosome (Ph1) -positive acute leukemia is the occasional presence of both lymphoid and myeloid features in the same leukemia. This phenomenon has provided evidence supporting the theory that this subtype of acute leukemia arises from lymphoidmyeloid stem cell/pluripotent progenitors. Very few reports, however, have described immunophenotype, especially CD34 antigen, of Ph1+ acute lymphoblastic leukemia (ALL). It has been reported that CD34, human progenitor cell antigen (HPCA-1), is found on a multipotent progenitor cell, whereas CD34 is not found on normal peripheral blood cells. Here, we report that high frequency of CD34 expression was found in children with Ph1+ ALL : CD34 was positive for six out of six patients tested. These findings suggest the involvement of a pluripotent stem cell in Ph 1-positive ALL.
