BCL-2 Expression and Prognosis in Childhood Acute Leukemia

Abstract

Bcl-2 expression and its prognostic value were evaluated in 42 children with acute leukemia. The Bcl-2 expression of the leukemic blast cells was measured quantitatively by flow cytometry and was further analyzed by the simultaneous immunostaining of Bcl-2 with the surface membrane antigens, DNA, Ki-67 antigen. All of the cases showed a consistent expression of Bcl-2 protein; virtually all leukemic lymphoblasts were Bcl-2 positive. Although the expression of Bcl-2 varied widely from 7 to 80 × 10³ MESF units, no significant difference was found, in the mean value between the patients with acute lymphoblastic leukemia and those with acute myeloblastic leukemia. In more than half of the patients with AML, intraclonal heterogeneity of Bcl-2 expression was observed. The expression of Bcl-2 showed no apparent fluctuations during the different phases of the cell cycle. However, the proportion of Bcl-2-positive and -negative cells during the cell cycle was different between ALL and AML patients. In the ALL patients, few Bcl-2-negative cells were detected only in the GI phase, whereas in the AML patients Bcl-2-negative cells were detected in the S and G2/M phases, as well as in the G1 phase. No apparent difference was found in Bcl-2 expression between the Ki-67-negative noncycling population and the Ki-67-positive cycling population. Of the clinical features of these patients, only CD34 expression in the ALL patients was associated with high levels of Bcl-2 expression. In the 28 untreated cases of ALL, high expression of Bcl-2 was not an unfavorable factor for the outcome of this disease.

Key Words:

• Bcl-2 protein
• cell cycle
• childhood acute leukemia
• flow cytometry
• prognosis

Additional information

Notes on contributors

Masahito Tsurusawa

Joyce Laing works in the Department of Child and Family Psychiatry, Playfield House, Cupar, Fife, and is a Consultant Art Therapist to Psychiatric Hospitals and Prisons and Chairwoman of the Scottish Society of Art and Psychology.

Dr Niculescu Dan, Centrul de Reumatologie, Str. J. (F)ucick no. 5, Bucuresti, Romania

Anni Vilppula, Department of Medicine, Paimio Hospital, Preitilä, Finland

G. Tausch, Department of Rheumatology, Municipal Hospital of Vienna-Lainz, Wolkersbergenstraße 1, A-1130Wien, Austria

Dr Guido Gothoni, Medica Pharmaceutical Company Ltd., P.O. Box 325, SF-00101 Helsinki 10, Finland

A. Elman, Dept. of Rheumatology, Karolinska sjukhuset, Stockholm, Sweden

Hannu Paitälä, Rheumatism Foundation Hospital, Heinola, Finland

Jonas Jonsson, National Bacteriological Laboratory, S-105 21 Stockholm, Sweden