Biomedical subjects

G J Watt

Publications and source records attributed to G J Watt.

5 recordsLinked to original sources

PubMed1987

Pharmacological modulation of erythrocyte autoimmune reactions in mice.

Injection of mice with rat erythrocytes induces both anti-rat and autoimmune anti-erythrocyte responses. The autoimmune response is under active suppression which can be demonstrated by transfer of spleen cells from immunised donors to naive recipients subsequently injected with erythrocytes. This system allows investigation of immunemodulatory agents on responses to self and non-self antigens in three ways the autoantibody and anti-rat erythrocyte responses in mice receiving the drugs and rat erythrocytes; the responses in mice receiving transferred cells from dosed immunised donors; and the responses in mice receiving transferred cells from non dosed immunised donors and themselves receiving erythrocytes plus drugs. The effect of a range of compounds with immunemodulatory activity was examined in the three test situations and both suppression and enhancement of the autoimmune response were observed. Comparison of effects on anti-rat and autoimmune antibody levels has confirmed previous results that these responses are subject to separate controlling mechanisms.

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PubMed1987

Identification of rat erythrocyte antigens with a new non-radioactive immunoprecipitation technique.

In order to examine how rat erythrocytes stimulate erythrocyte autoantibody production at the molecular level, we have identified rat erythrocyte antigens by immunoprecipitation and western blotting using monoclonal antibodies and antisera. A novel non-radioactive immunoprecipitation technique was used, which employed biotin as a label and a luminescent detection system. The new method was validated by comparison with conventional immunoprecipitation using 125I. Glycophorins of relative molecular mass (Mr) 81,000 and 38,000 were found to be the major antigenic components of rat erythrocytes, while band 3 (the most abundant erythrocyte membrane protein) was not recognized by rat-specific antibodies. The same surface antigens were recognized by sera from mice producing erythrocyte autoantibodies and by sera from mice in which autoantibody production was suppressed. Nine other minor rat-specific antigens were identified by blotting, ranging in Mr from 23,000 to 147,000. Analysis of the integral membrane proteins of rat and mouse erythrocytes by sodium dodecyl sulphate (SDS) electrophoresis followed by silver or periodic acid-Schiff (PAS) stains revealed differences between the glycophorins, but not between rat and mouse band 3. Thus, the major antigenic differences correspond to discernible biochemical differences between rat and mouse erythrocyte sialoglycoproteins.

Animals↗

PubMed1986

Characterization of suppressor-inducer cells which control the production of rat erythrocyte-induced anti-erythrocyte autoantibodies.

Mice immunized with rat erythrocytes produce autoantibodies to their own red blood cells, distinct anti-rat agglutinins and autoantigen-specific suppressor cells. Suppressor cells were detected by adoptive transfer of rat erythrocyte-immunized spleen cells to naive recipients. Such recipients failed to make erythrocyte autoantibodies after immunization with rat erythrocytes although their anti-rat erythrocyte response was unimpaired. Depletion and enrichment studies were performed to identify the cell type(s) which transfer suppression. B cell depletion of rat erythrocyte-immunized spleen cells by passage over Ig/anti-Ig-coated bead columns abrogated the transfer of suppression. However, suppression was still transferred after rat erythrocyte immunized spleen cells were passed over beads coated with a complex of 4-azido-2-nitrophenyl (NAP)-mouse IgG-rabbit IgG anti-NAP suggesting that T cells bearing Fc gamma receptors are not responsible for suppression. Positively selected B cells from rat erythrocyte-immunized spleen cells caused some suppression of erythrocyte autoantibodies but only after high numbers of cells were transferred. Neither positively selected Lyt-1+2- nor Lyt-1-2+ T cell subpopulations transferred suppression. By contrast, rat erythrocyte-immunized spleen cells which contained a mixture of B memory and T cells were suppressive and retained their suppressor activity after removal of Lyt-1-2+ but not Lyt-1+2- cells. It is proposed that these Lyt-1+2-T cells belong to a distinct population of suppressor-inducer cells which together with memory B cells stimulate the generation of effector T suppressor cells in naive recipients.

Animals↗

PubMed1986

Carrier-specific induction of suppressor cells controlling anti-erythrocyte autoantibody production in mice.

Mice immunized with rat erythrocytes develop anti-erythrocyte autoantibodies, distinct anti-rat erythrocyte agglutinins, and suppressor-inducer cells, which regulate the production of autoantibody but not anti-rat erythrocyte agglutinins upon transfer to naive recipients. In this report, we have tried to determine the specificity of the suppressor-inducer cells. CBA/N mice (which express an X-linked genetic B-lymphocyte defect) immunized with rat erythrocytes developed no autoantibodies but normal levels of anti-rat erythrocyte antibodies and suppressor-inducer cells, thereby suggesting that neither idiotypes on autoreactive B cells nor idiotypes on autoantibody itself, stimulate suppressor-inducer cells. In contrast, rat erythrocyte-primed spleen cells suppressed both a primary 2,4,6 trinitrophenyl (TNP) response and anti-erythrocyte autoantibody production (but not anti-rat erythrocyte antibodies) upon transfer to naive recipients and challenge with TNP-rat erythrocytes. It is considered that the suppressor-inducer cells are carrier-specific and that they are not stimulated by idiotypes on either autoantibody or autoreactive B cells.

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PubMed1985

Functional differences between B cell-depletion techniques in removing memory B cells. Relevance to anti-erythrocyte autoantibody-specific suppressor cells.

The efficiency of a number of B cell-depletion techniques was examined in a functional assay. CBA (Iga) mice were primed with rat erythrocytes and their spleen cells transferred, before and after B cell depletion, to mice of the allotype-congenic strain Igb. The recipients were challenged with rat erythrocytes and their anti-erythrocyte autoantibody response was measured together with the donor (Iga) and host (Igb) anti-rat erythrocyte antibody levels. Transferred unseparated cells suppressed erythrocyte autoantibodies and produced high levels of anti-rat erythrocyte antibodies. Transfer of panned, rosetted or nylon wool-passaged cells neither altered donor anti-rat erythrocyte antibody levels nor abrogated suppression. By contrast, passage of rat erythrocyte-primed B cells over Ig-anti-Ig-coated beads resulted in removal of donor rat-primed B cell activity and loss of suppressor cells. The B cell-depletion techniques were effective at removing B cells as judged by the reduced number of fluoresceinated anti-Ig-labeled cells among unbound cells although analysis on a fluorescein-activated cell sorter revealed that the most effective method was depletion on Ig-anti-Ig-coated beads. B cell depletion by panning removed the capacity of virgin but not primed cells to make adoptive antibody responses after transfer suggesting that the primed cells most efficient in adoptive transfer have a lower density of surface Ig than virgin cells. Treatment of donors with drugs which abrogated transferrable suppression of erythrocyte autoantibodies did not alter donor anti-rat erythrocyte antibody levels in recipients. It is considered that rat primed B cells are involved in the suppression of erythrocyte autoantibodies by acting as selective antigen-presenting cells for T suppressor inducer cells, rather than through an anti-rat erythrocyte antibody feedback mechanism.

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