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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS. Meshes: Acute Disease, Animals, CD8-Positive T-Lymphocytes, Corneal Neovascularization, Corneal Transplantation, Cytotoxicity Tests, Immunologic, Cytotoxicity, Immunologic, Graft Rejection, Graft Survival, Lymphocyte Activation, Lymphocyte Depletion, Male, Mice, Mice, Inbred BALB C, Mice, Inbred C57BL, Mice, Knockout, T-Lymphocytes, Cytotoxic, Transplantation, Homologous.
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Do cytotoxic T cells play no essential role in acute rejection of orthotopic corneal allografts in mice? Context: To determine whether cytotoxic T cells of the direct alloreactive type are activated and responsible for early, acute failure of orthotopic corneal allografts observed in eyes of C57BL/6 but not of BALB/c mice. Corneas from BALB/c and BALB.B mice were placed orthotopically in eyes of C57BL/6 and beta-2 microglobulin knockout mice (deficient in CD8(+) cytotoxic T cells). Graft fates were assessed clinically, and the T lymphocytes of recipients were assayed for the capacity to lyse target cells bearing donor major (MHC) and/or minor histocompatibility (minor H) antigens (direct and indirect pathways, respectively). RESULTS. Similar to BALB/c recipients, C57BL/6 mice with rejected cornea allografts acquired donor minor H-specific T cells. Unlike BALB/c recipients, C57BL/6 mice-both rejectors and acceptors-acquired donor MHC-specific T cells. beta-2 Microglobulin knockout mice showed rejection of corneal allografts in a manner indistinguishable from C57BL/6 mice, including early, acute rejection, yet T cells from beta-2 microglobulin knockout recipients of corneal allografts displayed no cytotoxic T cells specific for either donor MHC or minor H alloantigens.
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Although C57BL/6 mice acquired donor MHC-specific cytotoxic T cells (direct alloreactive cells), neither these cells nor donor minor H-specific cytotoxic T cells (indirect alloreactive cells) play any essential role in corneal allograft rejection, including the early acute failure uniquely observed in C57BL/6 eyes. Final Decision: yes