Detecting variable (V), diversity (D) and joining (J) gene segment recombination using a two-colour fluorescence system.

Background: Diversity of immunoglobulins and the T cell antigen receptors is achieved via the recombination activating gene (RAG)-mediated rearrangement of variable (V), diversity (D) and joining (J) gene segments, and this underpins the efficient recognition of a seemingly limitless array of antigens. Analysis of V(D)J recombination activity is typically performed using extrachromosomal recombination substrates that are recovered from transfected cells and selected using bacterial transformation. We have developed a two-colour fluorescence-based system that simplifies detection of both deletion and inversion joining events mediated by RAG proteins.

Wellcome Trust/EBI 2009 Meeting Report - Perspectives in Stem Cell Proteomics: 22-23 March 2009, Wellcome Trust Conference Centre, Hinxton, UK.

This report summarises the recent "Perspectives in Stem Cell Proteomics" meeting that was held at the Wellcome Trust Conference Centre, Hinxton, UK in March 2009. The aim of the meeting was to explore the current status of proteomics in stem cell biology. Several themes encompassing technological and biological studies demonstrated the close relationship that must exist between the two communities in order to maximise our understanding of stem cell behaviour.

Proteolytic activation of the cytotoxic phenotype during human NK cell development.

NK cells induce apoptosis in target cells via the perforin-mediated delivery of granzyme molecules. Cytotoxic human NK cells can be generated by IL-15-mediated differentiation of CD34(+) cells in vitro and these cultures have been used extensively to analyze the development of the NK cell surface phenotype. We have used NK cell differentiation in vitro together with protease-deficient human NK cells to analyze the acquisition of the cytotoxic phenotype.

A family with Papillon-Lefevre syndrome reveals a requirement for cathepsin C in granzyme B activation and NK cell cytolytic activity.

Activation of granzyme B, a key cytolytic effector molecule of natural killer (NK) cells, requires removal of an N-terminal pro-domain. In mice, cathepsin C is required for granzyme processing and normal NK cell cytolytic function, whereas in patients with Papillon-Lefèvre syndrome (PLS), loss-of-function mutations in cathepsin C do not affect lymphokine activated killer (LAK) cell function. Here we demonstrate that resting PLS NK cells do have a cytolytic defect and fail to induce the caspase cascade in target cells.

Effect of addition of FLT-3 ligand and megakaryocyte growth and development factor on hemopoietic cells in serum-free conditions.

The aim of this study was to clarify the mechanisms that regulate hematopoietic cell expansion in vitro by identifying defined culture conditions. We report the results of experiments with CD34(+) cells from cord blood (CB, n = 13), bone marrow (BM, n = 4), and mobilized peripheral blood stem cells (PBSC, n = 5) using two combinations of cytokines: (A) granulocyte colony-stimulating factor (G-CSF), interleukin-3 (IL-3), interleukin-6 (IL-6), stem cell factor (SCF), erythropoietin (EPO), insulin-like growth factor-1 (IGF-1), basic fibroblast growth factor (FGF-b) and (B) combination A plus FLT3 ligand (FL) and megakaryocyte growth and development factor (PEG rhMGDF). Cultures of immunoselected CD34(+) cells were performed in serum-free liquid medium without serum substitutes.

AC133+ G0 cells from cord blood show a high incidence of long-term culture-initiating cells and a capacity for more than 100 million-fold amplification of colony-forming cells in vitro.

AC133+ cells may provide an alternative to CD34+ cells as a target for cell expansion and gene therapy protocols. We examined the differences in proliferative potential between cord blood selected for AC133 or CD34 in serum-free, stroma cell-free culture for up to 30 weeks. Because most hemopoietic stem cells reside within the G0/G1 phase of the cell cycle, we combined enrichment according to AC133 or CD34 expression with G0 position in the cell cycle to identify populations enriched for putative stem cells.