Comparison of anthracycline-induced death of human leukemia cells: programmed cell death versus necrosis.

We investigated the mode of cell death induced by the anthracyclines, aclarubicin, doxorubicin and daunorubicin in the human leukemia cell lines, HL60 and Jurkat. The cells were incubated with drug concentrations up to 500 nM for periods between 3 and 24 hours, followed by morphological and biochemical analyses. All three substances induced DNA fragmentation, evident as DNA laddering and appearance of cells with hypodiploid DNA content, externalization of phosphatidyl serine, activation of caspases and degradation of the apoptosis-specific endonuclease inhibitor DFF45. However, concentrations and times necessary for these effects to occur were different, aclarubicin being the quickest acting drug with a lag phase of 3 h, followed by daunorubicin with 6 h and doxorubicin with 24 h. More importantly, aclarubicin induced these effects while the cell membrane was intact, whereas doxorubicin and daunorubicin led to immediate loss of membrane integrity. Programmed cell death is characterised by preservation of membrane integrity in order to allow removal of apoptotic bodies, whereas cell rupture is an early event in necrosis. We therefore suggest that, in our experimental settings, doxorubicin- and daunorubicin-induced cell death occurs by necrosis, while aclarubicin induces programmed cell death.

Development of an allergy test model: activation of human mast cells with potentially allergenic substances.

Due to the permanent increase of newly developed and already existing allergies, simple, quick, and reliable test models for detecting potentially allergenic substances are still required. Here, we describe the development of a new in vitro allergy test based on isolated primary mast cells (MC) of non-allergic patients from lung tissue and foreskin specimens, respectively. To establish the specificity of the test model we used primary MC stimulated with immunoglobulin E (IgE), human recombinant stem cell factor (hrSCF), and anti-IgE antibodies to release significant amounts of histamine indicating the ability of MC to cause a hypersensitivity reaction of the immediate type. The general applicability of this test model for detecting allergenic substances could be confirmed by histamine release of primary MC stimulated with sera of patients suffering from house dust allergy, and the corresponding antigen Dermatophagoides pteronyssinus. The results of the present work suggest that this newly developed human in vitro model provides the opportunity of testing substances for their allergenic potential within days and at low costs. This could also be of particular interest for newly produced compounds.