Biomedical subjects

R Aspinall

Publications and source records attributed to R Aspinall.

44 records · Page 3Linked to original sources

PubMed1989

Turnover of ED2-expressing macrophages in the thymus cortex of rats.

To investigate the turnover of thymic ED2+ cortical macrophages, vascular thymus transplantation in RT7-congenic rats were performed. Thymus graft cell suspensions were analyzed using ED2 in combination with congenic markers. Immunohistology of thymus graft sections was performed to demonstrate the immigration and persistence of these macrophages at several time points after transplantation. In contrast to other mobile thymus cells like thymocytes and interdigitating cells, most ED2+ cortical macrophages showed a slow turnover rate. At 76 days after transplantation more than 30% of ED2+ macrophages were still of donor origin. The migration properties of these macrophages are discussed in relation to their presumed role in thymocyte maturation and proliferation.

Animals↗

PubMed1987

Increased yields of IL-2 in media conditioned by MLA 144 cells.

The gibbon leukaemia cell line MLA 144 produces IL-2 constitutively, and has been used as a source of IL-2 for the in vitro growth of T cells from a range of species. We have tried to increase the amount of IL-2 present in conditioned medium produced by this cell line, by manipulating the growth conditions and using compounds known to increase IL-2 production in other cell lines. We found that conditioned media containing a higher amount of IL-2 could be obtained from 72 h cultures of MLA 144 cells originally seeded at 4 X 10(5) cells/ml in DMEM containing 10% FBS and supplemented with 2-ME at 5 X 10(-5) M and PMA at 10 ng/ml.

Animals↗

PubMed1986

Immunolocalization of keratan sulphate in the human embryonic cornea and other human foetal organs.

An antibody raised against keratan sulphate was used to localize keratan sulphate in the human embryonic cornea and other human foetal organs. It was found that keratan sulphate was present in the corneal endothelium, as well as in the corneal stroma. In contrast, no keratan sulphate could be demonstrated in the corneal epithelium or in any posterior parts of the human foetal eye. Human corneal stromal cells grown in monolayers in tissue culture lost their capacity to bind this antibody. This suggests that explantation in vitro decreases or alters the expression of keratan sulphate in this cell type. Keratan sulphate was found to be present in abundant quantities in human embryonic cartilage and to a lesser extent in placenta. In contrast, keratan sulphate could not be detected in the foetal intestine, liver, suprarenal glands, the umbilical cord or in the foetal yolk sack.

Antibodies, Monoclonal↗

PubMed1985

Analysis of the xenogeneic T-cell response to murine H-2 negative embryonal carcinoma cells.

Murine embryonal carcinoma cells are the stem cells of teratocarcinomas. They do not express H-2 antigens and previous reports have shown that these cells are not killed by major histocompatibility complex (MHC) restricted murine cytotoxic T cells. Here we report that effectors generated in MLCs between responders from a W3/13 enriched, NK-cell-depleted, rat spleen population, and spleen stimulators from 129 mice can lyse 129 embryonal carcinoma (EC) cells, but not CBA EC cells. A similar pattern of specific lysis of EC cells was seen with effectors generated in MLCs between rat lymph node and mouse spleen stimulators. Following priming in vivo with 129 EC cells, the frequency of cytotoxic T lymphocyte precursors against both 129 EC cells and 129 blast targets was increased when compared with the frequency found in age- and sex-matched unprimed animals. This response shows both specificity and memory and we conclude from this that it is due to rat T cells recognizing mouse xenogeneic antigens.

Animals↗

PubMed1984

Enrichment of rat NK cytotoxicity for H2-negative murine embryonal carcinoma cells by panning and short-term culture in TCGF.

The rat natural killer (NK) cell, defined here by spontaneous lysis of H2-negative embryonal carcinoma (EC) cells, was investigated with respect to its antigenic phenotype. Rat spleen cells were separated by panning into adherent and non-adherent populations after incubation with monoclonal antibodies defining differentiation antigens of rat lymphoid cells. This method achieved considerable NK enrichment in some of the panned populations (for example, W3/13 non-adherent cells, up to 20-fold), but emphasized the heterogeneous surface antigen expression of the NK cell type. These enrichment procedures were used to establish bulk cultures of rat NK cells which increased in specific activity over several weeks when grown in T cell-growth factor (TCGF) and could be cloned in soft agarose.

Animals↗

PubMed1983

An investigation into the B lymphopoietic capacity of long-term bone marrow cultures.

A suspension of nucleated femoral (BALB/c x CBA) bone marrow cells was inoculated, either into glass flasks or into flasks coated with a preformed syngeneic marrow derived monolayer, and cultured for long periods in media supplemented with hydrocortisone sodium succinate. Long term analysis of the lymphoid status of these cultures was then carried out whilst they were producing CFU-S cells. The results show that T cells expressing the Thy 1 marker were present for up to 10 weeks, surface immunoglobulin positive (sIgM+) B cells were present for at least 6 weeks, whereas pre-B cells were present for no longer than one week. Pre-B, B and T cells were all present at levels well below those found in normal healthy bone marrow. When cultures were free of both B and pre-B lymphocytes, the cells collected from them were used to reconstitute lethally irradiated mice. Reconstitution was of the type (A x B) leads to A and approximately 2 months elapsed before reconstituted animals were analysed. The results show that despite the loss of pre-B cells from these cultures, precursors of B lymphocytes at earlier stages of differentiation were present for long periods, but were only capable of differentiation into sIgM+ B cells in vivo.

Animals↗

PubMed1983

Kinetics of sequential appearance of IgM and IgD on B lymphocytes in the bone marrow of the adult mouse.

The relationship between the expression of IgM, and IgD at the B-cell surface, was examined in the adult murine bone marrow. Groups of mice were injected with hydroxyurea, which prevents DNA synthesis by blocking the production of deoxyribonucleotides. The numbers of cells per femur, expressing either IgM alone or in conjunction with IgD were followed at 24 hr intervals after the drugs administration. Other mice were injected with tritiated thymidine over an 8 hr period. The appearance of radioactive label within cells expressing IgM alone or with IgD, was followed over a 5 day period. Both sets of results showed that IgM bearing cells were derived from a rapidly dividing precursor cell pool, by a process which takes more than 24 hr and does not require DNA synthesis. Cells expressing IgM and IgD together were also produced from rapidly dividing precursors. This developmental process takes more than 48 hr, does not require DNA synthesis and may go via an intermediate stage namely the cell expressing IgM alone.

Animals↗

PubMed1980

Lymphocyte differentiation and major histocompatibility complex antigen expression in the embryonic thymus.

During embryogenesis, stem cells migrate from the bloodstream into the thymic rudiment where they proliferate and differentiate into T lymphocytes. The epithelial cells of the thymic stroma may influence these processes by providing hormonal and/or contact stimuli to the developing lymphoblasts. Recently, it has been shown that T cells 'learn' to recognise the major histocompatability complex (MHC) antigens during thymic lymphopoiesis and become MHC-restricted. Their subsequent response to other antigens can only occur in the context of MHC antigens of the haplotype encountered in the thymus. Little is known, however, of antigen expression on the thymic stroma which may provide the reference framework on which this MHC restriction is based. In this study we use monoclonal antibodies to show that antigens of the K and I regions of the MHC are detectable on cells of the embryonic mouse thymic stroma from around the 14th day of gestation, just when lymphocyte differentiation is commencing. Furthermore, I-region antigen (Ia antigen) expression is probably limited to thymic epithelium at this stage of gestation and we have not detected Ia on other epithelial tissues of the pharyngeal complex. This pattern of expression is consistent with a role for the thymic stroma in MHC restriction, perhaps by the selection of lymphoid cells for survival on the basis of their recognition of stromal MHC determinants.

Animals↗