1. the T cells whose receptors recognize self antigens presented by MHCa have be
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Question
1. the T cells whose receptors recognize self antigens presented by MHCa have been expanded in the thymus.
2. the T cells whose receptors recognize self antigens presented by MHCa have been eliminated in the thymus.
3. graft rejections can be mediated by antibodies.
4. the T cells whose receptors recognize self antigens presented by MHCaxb have been eliminated in the thymus.
5. the T cells whose receptors recognize self antigens presented by MHCaxb have been expanded in the thymus.
6. the T cells whose receptors recognize self antigens presented by MHCb have been eliminated in the thymus.
7. the T cells whose receptors recognize self antigens presented by MHCb have been expanded in the thymus.
8. bone marrow-derived cells cannot induce positive selection, because the transplanted MHCaxb F1 bone marrow cells are the only source of MHCb molecules in the thymus.
9. bone marrow-derived cells must be able to mediate negative selection of MHCb-alloreactive T cells, because the transplanted MHCaxb F1 bone marrow cells are the only source of MHCb molecules in the thymus.
10. bone marrow-derived cells cannot mediate negative selection of MHCb-alloreactive T cells, because the transplanted MHCaxb F1 bone marrow cells do not express only MHCb molecules.
Bone marrow transplant from MHCaxbF, mouse into MHC recipient MHCaxbF MHCb bone marrow MHCa Skin graft from MHC mouse onto (MHCaXb MHCa) bone marrow chimea MHCaxbF, MHCb skin graft MHCbMHC chimera (MHCaxb MHCa) chimeric mouse tolerates MHC skin graftExplanation / Answer
These experimental results imply that the chimeric mice are tolerant to skin grafts expressing MHCb molecules as long as they don’t have skin specific peptides that differ between strains a and b, so the skin graft is accepted.
1. the T cells whose receptors recognize self antigens presented by MHCa have been expanded in the thymus.(False)
2. the T cells whose receptors recognize self antigens presented by MHCa have been eliminated in the thymus.(True)
3. graft rejections can be mediated by antibodies.(False)
4. the T cells whose receptors recognize self antigens presented by MHCaxb have been eliminated in the thymus.(True)
5. the T cells whose receptors recognize self antigens presented by MHCaxb have been expanded in the thymus.(False)
6. the T cells whose receptors recognize self antigens presented by MHCb have been eliminated in the thymus. (True)
7. the T cells whose receptors recognize self antigens presented by MHCb have been expanded in the thymus.(False)
8. bone marrow-derived cells cannot induce positive selection, because the transplanted MHCaxb F1 bone marrow cells are the only source of MHCb molecules in the thymus. (True)
9. bone marrow-derived cells must be able to mediate negative selection of MHCb-alloreactive T cells, because the transplanted MHCaxb F1 bone marrow cells are the only source of MHCb molecules in the thymus.(True)
10. bone marrow-derived cells cannot mediate negative selection of MHCb-alloreactive T cells, because the transplanted MHCaxb F1 bone marrow cells do not express only MHCb molecules.(False)
Explanation: Bone marrow derived cells mediate negative selection in the thymus and when MHCaxbF1 bone marrow is injected into an irradiated MHCa mouse, the T cells mature on thymic epithelium and expresses only MHCa molecules, there will be a negative selection of Tcells which recognizes the self-peptides or antigens.
The chimeric mice which received the skin grafts are tolerant to the MHCb molecules. It confirms that the Tcell receptors which recognizes the self-antigens presented by MHCb is eliminated in the thymus. So bone marrow derived cells are inducing negative selection.
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