ABSTRACT
BACKGROUND: The recent advances in flow cytometric technology and the development of monoclonal antibodies have led to the important insights into the cell lineage and maturation stage of leukemia. The increased use of immunophenotyping in acute leukemia revealed the unusual anigen expression and biclonal or biphenotypic acute mixed lineage leukemia (AMLL). However, the data on their frequency and prognostic significance are still conflicting. METHODS: The immunophenotyping of leukemic cells (HLA-DR, CD10, CD19, CD20, CD22, CD3, CD5, CD7, CD13, CD33, CD61, TdT, cytoplasmic Ig, surface Ig) was performed by flow cytometry in 115 cases of acute leukemia between January 1994 and August 1996. Double-color immunofluorescent staining was performed in the cases expressing unusual antigens. RESULTS: 51 cases (44.3%) of 115 acute leukemias showed unusual antigens expression. These included 27 cases (38.6%) of 70 AML, 13 cases (43.3%) of 30 B-lineage ALL, 4 cases (50%) of 8 T-LL and 7 AMLL cases (6.1%) of 115 acute leukemias. CD7 (28.6%) and CD19 (11.4%) are expressed in AML, and CD13 (36.7%) and CD33 (26.7%) are expressed in ALL. Among 7 cases of AMLL, we could obtain the clinical data of 5 cases. The 4 cases of 5 AMLL failed to respond to induction chemotherapy or died before or during induction chemotherapy, and only one case showed partial remission. CONCLUSION: The unusual antigen expressions of acute leukemic cells are frequently observed, and the identification of relatively rare AMLL is very important, because AMLL showed poor response to the chemotherapy.