Biomedical subjects

J S Wotherspoon

Publications and source records attributed to J S Wotherspoon.

6 recordsLinked to original sources

PubMed1989

Graft-versus-host resistance induced by tolerant cell populations. Evidence against clonal deletion as a mechanism of transplantation tolerance.

Characterization of the effect of immunization of F1 hybrid hosts with low doses of parental cells has shown that the F1 hybrid response to the receptor for the unshared MHC antigen on the immunizing cell induces specific resistance to a GVH challenge from cells of the same parental strain. We have shown that cells from parental rats tolerant to the unshared MHC antigens are capable of inducing GVH resistance in F1 hybrids. Unlike cells from normal parental rats that induce GVH resistance only when given in low immunizing doses of 10(6) cells, 10(6)-10(8) cells from tolerant donors effectively immunize F1 hybrids. This effect does not appear to be the result of passive transfer of suppressor cells from the tolerant donor. An alternative explanation is that tolerant populations contain cells that express the receptor for the tolerated alloantigen. The finding that normal parental populations that have been deleted of receptor-bearing cells by passage through semiallogeneic intermediate hosts do not induce GVH resistance, whereas tolerant cell populations do, confirms that clonal deletion does not adequately account for the functional characteristics of the tolerant cells. Attempts to delete putative receptor-bearing cells from the tolerant population however produced equivocal results.

Animals↗

PubMed1988

Altered immunoglobulin expression and functional silencing of self-reactive B lymphocytes in transgenic mice.

Immunological tolerance has been demonstrated in double-transgenic mice expressing the genes for a neo-self antigen, hen egg lysozyme, and a high affinity anti-lysozyme antibody. The majority of anti-lysozyme B-cells did not undergo clonal deletion, but were no longer able to secrete anti-lysozyme antibody and displayed markedly reduced levels of surface IgM while continuing to express high levels of surface IgD. These findings indicate that self tolerance may result from mechanisms other than clonal deletion, and are consistent with the hypothesis that IgD may have a unique role in B-cell tolerance.

Animals↗

PubMed1988

A new microsphere-based immunofluorescence assay using flow cytometry.

The quantitative and qualitative capacities of flow cytometric analysis that have made it such a powerful tool in studies of cellular antigens have not previously been exploited when dealing with non-cellular antigens. A new immunofluorescence assay technique was developed, using an indirect staining procedure with monoclonal anti-kappa antibodies, to detect human free kappa light chains covalently bound to microspheres of a size suitable for flow cytometry. The strength of the fluorescent signal produced on the microspheres was related to the amount of antigen bound and the size of the beads. At the time of this work large microspheres (i.e., greater than 3 micron in diameter) suitable for this application were only available as suspensions of polysized beads. The fluorescent signal detected on labelled beads was optimized by selecting for analysis, on the basis of the forward angle laser scatter, only those beads of largest diameter. There are many potential applications for this technique - microspheres can be used for the presentation of virtually any antigen or antibody. The analytical benefits inherent in flow cytometry would be a significant advantage in the development of quantitative assays using this method.

Antibodies, Monoclonal↗

PubMed1988

Simultaneous cytometric analysis for the expression of cytoplasmic and surface antigens in activated T cells.

A method of two-colour immunofluorescence staining has been developed to allow the simultaneous analysis of both surface and cytoplasmic antigens. This involves the use of direct fluorochrome antibody conjugates for cell-surface antigen staining, followed by cell permeabilization and the staining of cytoplasmic antigens with biotinylated antibodies and streptavidin-fluorochrome conjugates. Fluorochrome-antibody conjugates bound to cell-surface epitopes were found not to be affected by the subsequent permeabilisation and cytoplasmic staining. This method was used to examine the surface phenotype of T cells expressing a cytoplasmic antigen, STA. STA is a unique determinant detected in activated human T cells by the monoclonal antibody K-1-21, which also recognizes a cross-reactive conformation-dependent epitope on human free kappa light chains. Cytometric analysis showed that STA is found in both Leu 2a+ cytotoxic/suppressor T cells and Leu 3a+ helper/inducer T cells but is not induced in the Leu 15+ population which contains suppressor T cells. STA was also shown to be an activation antigen in murine T cells.

Animals↗

PubMed1988

Postirradiation recovery of lymphoid cells in the rat.

Whole-body irradiation has been extensively used to ablate immune responsiveness in rodent recipients in adoptive allograft assays. This study was undertaken to determine the relative radioresistance and the tempo of regeneration, following whole-body irradiation, of cells involved in the allograft response. Six distinct cell populations have been identified in the lymphoid tissues of rats subjected to sublethal whole-body irradiation. The relative representation of these subpopulations was significantly different from that in nonirradiated controls. NK cells, macrophages, and plasma cells, which are present in very low numbers in cell suspensions prepared from normal lymphoid tissues, made up a significant proportion of the residual/regenerating population in the tissues of rats recovering from whole-body irradiation. More significantly perhaps, the mature T cell populations showed a significant increase in the T cytotoxic/suppressor to T helper cell ratio. These observations support the suggestion that a number of the cell types within the mixed cell population observed in the rejecting indicator grafts of irradiated recipients in adoptive allograft assays are host derived. The finding that the T cytotoxic/suppressor population is apparently more radioresistant than the T helper population supports a conclusion that graft rejection in irradiated recipients, restored with pure populations of T helper cells, may not be directly mediated by the injected cells but may be the result of collaboration between these and host-derived cytotoxic cell populations.

Animals↗

PubMed1986

The mechanism of prolonged graft survival following removal of the regional lymph node.

The immune responsiveness of rats in which the rejection of RT-1-incompatible neonatal heart grafts had been prevented by removal of the draining lymph node was examined. It was found that within three days of node removal animals developed a state of specific unresponsiveness characterized by the failure to reject secondary grafts made into the contralateral leg with intact draining nodes. Studies of recipients with long-surviving grafts revealed that their serum contained significant levels of cytotoxic alloantibody although their cells behaved like those from naive donors in mixed lymphocyte interactions, graft-versus-host responses, and adoptive allograft assays. There was no evidence for the presence of sensitized T cells or suppressor T cells in the tissues of recipients with long-surviving grafts. The findings support the suggestion that prolonged graft survival following node removal is due to enhancement actively induced by the passage of graft antigen into the circulation at a time when the induction of the cell-mediated response has been aborted by removal of the node regional to the graft.

Animals↗