Multicenter study to evaluate a new enumeration method for hematopoietic stem cell collection management.

BACKGROUND: CD34 flow cytometry is the gold standard for stem cell enumeration in peripheral blood at the mobilization stage and in the final apheresis product. The new stem cell mode of the Sysmex XN Series analyzer enumerates an immature cell population in the white progenitor and pathological cell (WPC) channel, based on the cell size, internal cellular complexity, and fluorescence intensity. STUDY DESIGN AND METHODS: In this multicenter study we analyzed 147 peripheral blood samples, 22 samples during collection of stem cells, and 45 samples from the apheresis product of 18 healthy allogeneic donors and 84 autologous patients. RESULTS: In this multicenter study we demonstrate that the XN stem cell enumeration method correlates well with viable CD34+ cells determined by flow cytometry during the stem cell mobilization phase to determine apheresis start time, during apheresis for real-time monitoring and adjustment, and for quality control of the final stem cell harvest. CONCLUSION: Our data show that there is an improvement in the correlation of XN stem cells and CD34+ cells in the peripheral blood during stem cell mobilization as well as in stem cell harvests compared to SE or XE Series analyzers. The XN stem cell enumeration method has a number of advantages compared to CD34 flow cytometry: it is fast, simple, reproducible, and less expensive. CE marking for the European market has been obtained, making the stem cell count on the XN analyzer a reportable clinical variable.

Differential effects of Viscum album extract IscadorQu on cell cycle progression and apoptosis in cancer cells.

Extracts from European mistletoe or Viscum album L. have been reported to exert cytotoxic and immunomodulatory effects in vitro and in vivo. The mechanism of this anti-tumoral activity is however, largely unknown. In this study we tested the hypothesis that IscadorQu, an aqueous fermented extract from the European mistletoe grown on oaks, induces tumor regression by cell cycle inhibition and/or interference with apoptotic signaling pathways in cancer cells. Also a possible effect on angiogenesis, which is a prerequisite for tumor growth in vivo, is studied in endothelial cell cultures. Furthermore, we examined which apoptotic signaling route is activated by staining cells for specific pro-apoptotic proteins. To characterize these properties, 6 different human cancer cell lines, one epidermis derived cell line and 2 endothelial cell cultures were incubated with different concentrations of IscadorQu. Cell cycle kinetics parameters were measured by bromodeoxyuridine (BrdU) pulse labeling and tubulin staining. Apoptotic responses were detected by M30 CytoDeath or Annexin V/propidium iodide assays. Characterization of the apoptotic pathway was performed by staining cells for active caspase 3, active caspase 8, cytochrome C and chloromethyl-X-rosamine. The results of this study show that sensitivity to IscadorQu treatment varies strongly between different cell lines. In sensitive cell lines, including tumor and endothelial cell cultures, IscadorQu caused early cell cycle inhibition followed by apoptosis in a dose-dependent manner. Apoptosis was induced by activating the mitochondrial but not the death receptor-dependent pathway.

Antigen degradation or presentation by MHC class I molecules via classical and non-classical pathways.

Major histocompatibility complex (MHC) class I molecules usually present endogenous peptides at the cell surface. This is the result of a cascade of events involving various dedicated proteins like the peptide transporter associated with antigen processing (TAP) and the ER chaperone tapasin. However, alternative ways for class I peptide loading exist which may be highly relevant in a process called cross-priming. Both pathways are described here in detail. One major difference between these pathways is that the proteases involved in the generation of peptides are different. How proteases and peptidases influence peptide generation and degradation will be discussed. These processes determine the amount of peptides available for TAP translocation and class I binding and ultimately the immune response.