Acute leukemia expressing the normal human hematopoietic stem cell membrane glycoprotein CD34 (MY10)

Thirty-one cases of acute leukemia with blast cells ≥70% positive for the hematopoietic stem cell Ag, CD34 (MY10, HPCA-1), were identified from the University of Nebraska Medical Center and The Johns Hopkins Oncology Center over an 18-month period. Fourteen of the cases were classified as early B-lineage ALL, 3 cases were other ALL subtypes, and 14 of the cases were ANLL. Five of the 17 cases of ALL expressed one or more myeloid-associated surface Ags, 3 ANLL cases expressed CD10 (CALLA, J5), and T-lymphoid Ags were present in 12 of 31 cases (1 T-cell ALL, 3 of 16 B-lineage ALL cases, and 8 of 14 ANLL cases). Eleven of 12 CD34⁺ ALL cases studied had abnormal karyotypes; only 7 of 12 CD34⁺ ANLL cases studied has abnormal karyotypes, and 3 of these were CD10⁺ ANLL. Six cases were Ph¹ positive, including the one mature B cell ALL, 4 early B-lineage ALL, and 1 CD10⁺ ANLL case. Good and poor prognosis subgroups of high frequency of expression of CD34 leukemias could be identified, generally, as would have been predicted by previously defined criteria. Thus, of the 10 Ph^1-negative early B-lineage ALL patients, 9 achieved CR (90%). At the other extreme, the CR rate of CD10^- ANLL was 4 of 11 (36%). The leukemias characterized by ≥70% of cells positive for CD34 form a relatively undifferentiated subset of the leukemia which may show features associated with more than one lineage, and if CD10^- and myeloid morphology, may respond poorly to therapy.