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Full-Text Articles in Life Sciences
Investigation Of Murine Spleen As A Niche For Hematopoiesis., Jonathan Tan, Helen O'Neill
Investigation Of Murine Spleen As A Niche For Hematopoiesis., Jonathan Tan, Helen O'Neill
Helen O'Neill
Background Spleen as a lymphoid tissue is specialized for monitoring blood and mounting immunity against blood-borne antigens. Antigen-presenting cells present in spleen commonly develop from bone marrow-derived precursors that enter blood circulation. However, a distinct splenic myeloid antigen-presenting cell subset described in this laboratory, namely “dendritic-like cells” (L-DC), has been hypothesized not to share a bone marrow origin. Methods In this study, the presence of endogenous hematopoietic progenitors in spleen was investigated by transplanting intact spleen into allotype-distinct recipients and monitoring development of progeny cells in grafted tissues. Results Successful engraftment of donor spleens was achieved for up to 4 …
Splenic Stromal Niches Support Hematopoiesis Of Dendritic-Like Cells From Precursors In Bone Marrow And Spleen., Pravin Periasamy, Jonathan Tan, Kristin Griffiths, Helen O'Neill
Splenic Stromal Niches Support Hematopoiesis Of Dendritic-Like Cells From Precursors In Bone Marrow And Spleen., Pravin Periasamy, Jonathan Tan, Kristin Griffiths, Helen O'Neill
Helen O'Neill
Objective The aims of this study are to test the ability of stromal cells from murine spleen to support hematopoiesis, to define the tissue source of precursors that seed these hematopoietic niches, and to determine the type of cells produced. Materials and Methods Cloned isolates of murine spleen stroma have been developed that support hematopoiesis. Analysis has been investigated in terms of tissue source of progenitors. Type and number of cells produced were analyzed by flow cytometry. Results Hematopoietic precursors that seed cocultures exist in spleen and bone marrow (BM), but not thymus. Cell production is highest if overlay cells …
Gene Signature Of Stromal Cells Which Support Dendritic Cell Development., Geneviève Despars, Pravin Periasamy, Jonathan Tan, Janice Abbey, Terence O'Neill, Helen O'Neill
Gene Signature Of Stromal Cells Which Support Dendritic Cell Development., Geneviève Despars, Pravin Periasamy, Jonathan Tan, Janice Abbey, Terence O'Neill, Helen O'Neill
Helen O'Neill
Spleen stromal cells are critical determinants of dendritic cell (DC) development in spleen. The spleen stromal line, namely STX3, supports DC differentiation in vitro from overlaid bone marrow cells while the lymph node stromal line, namely 2RL22, does not. Here we have characterised the hematopoietic support capacity of each stroma, and analyzed lineage origin of the stromal cell lines by gene profiling using microarrays. Stromal co-culture experiments were performed using bone marrow cells as a source of hematopoietic progenitors. A characteristic immature myeloid-like CD11c+CD11b+CD86+MHC-II−/loB220−CD8α− DC is produced after 14 days in STX3 cocultures, while 2RL22 cocultures produce only monocyte/macrophage-like cells. …
Detection Of Spliced And Unspliced Forms Of Germline Tcr-Vβ Transcripts In Extrathymic Lymphoid Sites, Janice Abbey, Helen O'Neill
Detection Of Spliced And Unspliced Forms Of Germline Tcr-Vβ Transcripts In Extrathymic Lymphoid Sites, Janice Abbey, Helen O'Neill
Helen O'Neill
Germline TCR-Vβ transcription is commonly considered an event coupled with rearrangement of TCR genes in T cells. The extent of germline Vβ transcription is studied here in a range of cell types and in several mouse strains. A sensitive semi-quantitative RT-PCR method was developed to specifically detect germline and not rearranged transcripts. Germline transcription of a range of different Vβ genes was detected along with rearranged transcripts in bone marrow, thymus, mesenteric lymph node and spleen. Some transcripts were also detected in low level in non-lymphoid tissues including heart, liver and brain. Expression was also studied in the C57BL/6J-β2microglobulin−/− (C57BL/6J-β2M−/−) …
Hematopoiesis Of Immature Myeloid Dendritic Cells In Stroma-Dependent Spleen Long-Term Cultures Occurs Independently Of Nf-Kb/Relb Function, Jonathan Tan, Keping Ni, Fei Le, Helen O'Neill
Hematopoiesis Of Immature Myeloid Dendritic Cells In Stroma-Dependent Spleen Long-Term Cultures Occurs Independently Of Nf-Kb/Relb Function, Jonathan Tan, Keping Ni, Fei Le, Helen O'Neill
Helen O'Neill
Objective The nuclear factor-κB (NF-KB)/RelB transcription factor plays an essential role in development of some dendritic cell (DC) subsets in mice. In this laboratory, immature myeloid DC are produced in vitro in a stroma-dependent murine spleen long-term culture (LTC) system. In LTC, DC differentiate from hematopoietic progenitors maintained within the stromal cell matrix. Expression and function of RelB in development of LTC-DC has been investigated, with a view to assessing the relationship between DC produced in this system and other known subsets of DC. Materials and Methods RelB expression by LTC-DC was confirmed by detection of protein by Western blotting, …
Mycoplasma Contaminants Present In Exosome Preparations Induce Polyclonal B Cell Responses., Helen O'Neill, Ben Quah
Mycoplasma Contaminants Present In Exosome Preparations Induce Polyclonal B Cell Responses., Helen O'Neill, Ben Quah
Helen O'Neill
Exosome fractions of dendritic cells (DC) produced in long-term cultures (LTC) were found to contain Mycoplasma contaminants. In this study, Mycoplasma-infected, -uninfected, and -reinfected cultures of DC and control cell lines have been compared for their capacity to activate lymphocytes. Using differential centrifugation, size fractionation, and inhibition assays, it has been possible to map Mycoplasma to the exosome or vesicle fraction purified from culture supernatant (CSN). Mycoplasma fractions were shown to induce proliferation of B and not T cells. The B cell response was sensitive to mitomycin C and primaquine, both known antibiotics, but resistant to protease and DNase, suggesting …
Cell Surface Expression Of A Peptide Encoded By The Unrearranged Tcr-Vβ8.2 Gene, Janice Abbey, Mark Hulett, Helen O'Neill
Cell Surface Expression Of A Peptide Encoded By The Unrearranged Tcr-Vβ8.2 Gene, Janice Abbey, Mark Hulett, Helen O'Neill
Helen O'Neill
Germline transcription of T-cell receptor (TCR) genes has been described in early lymphoid cells. The most common explanation for this phenomenon is that transcription of unrearranged Vβ genes directs gene usage during the rearrangement event. Germline transcription of the TCR-Vβ8.2 gene has been detected in a precursor T-cell line, C1-V13D, which shows no rearrangement at any of the TCR gene loci. This cell line also shows weak binding of specific anti-V 8.2 antibody to the cell surface, consistent with expression of a truncated TCR chain. RT-PCR has been used to confirm expression of spliced germline transcripts of TCR-Vβ8.2 in C1-V13D …
Heterogeneity Amongst Splenic Stromal Cell Lines Which Support Dendritic Cell Hematopoiesis, Geneviève Despars, Helen O'Neill
Heterogeneity Amongst Splenic Stromal Cell Lines Which Support Dendritic Cell Hematopoiesis, Geneviève Despars, Helen O'Neill
Helen O'Neill
Long-term cultures (LTC) producing dendritic cells (DC) have been previously established from spleen. LTC support the development of nonadherent cells comprising small DC progenitors and immature DC. Similarly, the splenic stroma STX3, derived from a LTC which ceased DC production, can support DC development from precursors in overlaid bone marrow. The STX3 stroma is an immortalised mixed population of endothelial cells and elongated spindle-shaped cells, thought to be fibroblasts. The stromal cell components of STX3 have been studied here. A panel of 102 cell lines was established by single-cell sorting. A range of clone morphology, including cobblestone cells and elongated …
The Immunogenicity Of Dendritic Cell-Derived Exosomes, Ben Quah, Helen O'Neill
The Immunogenicity Of Dendritic Cell-Derived Exosomes, Ben Quah, Helen O'Neill
Helen O'Neill
Exosome production represents an alternate endocytic pathway for secretion. Multivesicular endosomes (MVE) fuse with the plasma membrane expelling internal vesicles or exosomes from cells. Exosome production has been recently described for immune cells including B cells, dendritic cells (DC), mast cells, macrophages and T cells. Exosomes derived from some DC populations stimulate T lymphocyte proliferation in vitro and have potent capacity to generate anti-tumour immune responses in vivo. These reported studies have involved in vitro grown mature DC expanded from precursors with cytokines. However, immature DC produce higher numbers of exosomes than mature DC and this is thought to be …
Maturation Requirements For Dendritic Cells In T Cell Stimulation Leading To Tolerance Versus Immunity, Helen O'Neill, Jonathan Tan
Maturation Requirements For Dendritic Cells In T Cell Stimulation Leading To Tolerance Versus Immunity, Helen O'Neill, Jonathan Tan
Helen O'Neill
The model that dendritic cell (DC) "maturation" describes the change from an immature, antigen-capturing cell to a mature, antigen-presenting cell is well-established. Classification of DCs in terms of function has been problematic previously. It is therefore proposed that mature and not immature DCs are responsible for antigen presentation and stimulation of T cells. Furthermore, DC antigen presentation to T cells can have two outcomes: tolerance or immunity. The particular outcomes appear to be determined by the activation state of the mature DC. DCs can be activated by a range of environmental stimuli or "danger signals". Here, the hypothesis is advanced …