Leukaemic CD5+ B-cell apoptosis: co-incidence of cell death and DNA fragmentation with reduced bcl-2 expression.
Apoptosis and bcl-2 expression were characterized in leukaemic B cells during in vitro culture. Prior to culture, > 85% of cells from each B-CLL patient expressed high levels of bcl-2. Despite this, all leukaemic B-cell populations underwent apoptosis in vitro. Furthermore, bcl-2 was down-regulated such that the B cells displayed a bcl-2high and /or bcl-2low phenotype. However, the overall number of bcl-2-positive cells remained constant. We propose that although enhanced survival of leukaemic B cells in vivo is mediated by the sustained expression of bcl-2, it is apparent that additional mechanisms are capable of overriding the protective effect of bcl-2 when bcl-2 when bcl-2 is expressed at reduced levels.
Tangye
S G
SG
Immunobiology Unit, University of Technology, Sydney, New South Wales, Australia.
Raison
R L
RL
D017209:Apoptosis; D001402:B-Lymphocytes / Q000473:pathology; D018956:CD5 Antigens / Q000235:genetics; D002470:Cell Survival; D004273:DNA, Neoplasm / Q000235:genetics; D015870:Gene Expression; D006801:Humans; D016393:Lymphoma, B-Cell / Q000235:genetics / Q000473:pathology*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D019253:Proto-Oncogene Proteins c-bcl-2; D014407:Tumor Cells, Cultured
D018956:CD5 Antigens; D004273:DNA, Neoplasm; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2