Spontaneous programmed death (apoptosis) of B‐chronic lymphocytic leukaemia cells following their culture in vitro

Abstract

Summary When B‐cell lymphocytic leukaemia (B‐CLL) cells derived from peripheral blood were cultured in vitro, a substantial proportion of them spontaneously died by apoptosis. This type of cell death is morphologically and biochemically distinct from necrosis and has previously been found to occur under physiologic and certain pathologic conditions where cell deletion appears controlled and biologically meaningful. By 30 h of culture, approximately 20% of the unfractionated B‐CLL cells were affected. There was no significant difference in the incidence of apoptosis in T‐cell depleted and undepleted cultures or when either autologous or normal human serum was used. Furthermore, seeding densities of 2 × 106 and 5 × 105 cells/ml resulted in a similar incidence of apoptosis, indicating that cell density was unlikely to be a contributing factor in producing the death. The finding that B‐CLL cells spontaneously die in vitro has at least two important implications. Firstly, previous work relating to some of the functions of B‐CLL cells and their interactions with T cells may require re‐evaluation. Secondly, an understanding of the mechanisms involved in the induction of apoptosis in this disease may have therapeutic consequences.

Crosstalk among Bcl-2 family members in B-CLL: seliciclib acts via the Mcl-1/Noxa axis and gradual exhaustion of Bcl-2 protection

“…B-CLL cells were 490% pure as determined by flow cytometry. Consistent with previous reports, 15 in vitro culture of B-CLL cells was accompanied by a moderate spontaneous increase in apoptosis. Increasing doses (10,25 and 50 mM) of seliciclib resulted in dose-dependent increase of apoptosis ( Figure 1a).…”

The BH3 mimetic compound, ABT-737, synergizes with a range of cytotoxic chemotherapy agents in chronic lymphocytic leukemia

“…It is well recognized that multiple factors, both intrinsic and extrinsic (for example cytokines, use of stromal co-culture to resemble the in vivo microenvironment), influence responsiveness of CLL cells in culture. [47][48][49] We speculate that culturing CLL cells in primary patient serum or plasma, instead of fetal calf serum used by most other investigators, could account for the reduced sensitivity observed in some of the samples. Given the variable responses (with LC 50 values ranging over 100-fold), we were particularly interested in identifying which factor(s) that could account for the differences between samples because it is highly likely that clinical responses to compounds like ABT-737 will also be variable.…”

Physical contact with endothelial cells through 1- and 2- integrins rescues chronic lymphocytic leukemia cells from spontaneous and drug-induced apoptosis and induces a peculiar gene expression profile in leukemic cells

“…1,2 This observation suggests that the apoptotic resistance is not intrinsic to leukemia B cells but that extrinsic factors are necessary for the prolonged survival of CLL cells.…”