Antiviral immunity and T-regulatory cell function are retained after selective alloreactive T-cell depletion in both the HLA-identical and HLA-mismatched settings. |
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Authors: | Jeffrey K Davies Mickey B c Koh Mark W Lowdell |
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Institution: | Department of Haematology, Royal Free & University College Medical School, London, United Kingdom, UK. j.davies@rfc.ucl.ac.uk |
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Abstract: | Nonselective T-cell depletion reduces the incidence of severe graft-versus-host disease after allogeneic hematopoietic stem cell transplantation, but the cost is delayed and disordered antigen-specific immune reconstitution and increased infection. We use a method of selective depletion of alloreactive T cells expressing the activation marker CD69 after coculture with stimulator cells in a modified or standard mixed lymphocyte reaction. The technique has been shown to reduce alloreactivity while retaining third-party responses in vitro and, in a mismatched murine model, led to donor T-cell engraftment with a virtual absence of graft-versus-host disease and increased survival. We show in a human HLA-mismatched and unrelated HLA-identical setting that this technique retains >80% of specific cellular antiviral activity by cytomegalovirus-tetramer analysis and cytomegalovirus/Epstein-Barr virus peptide-stimulated interferon-gamma ELISpot assay. Furthermore, CD4(+) CD25(+) T-regulatory cells are not removed by this method of selective allodepletion and retain their function in suppressing allogeneic proliferative responses. Preservation of antiviral cytotoxic T lymphocytes in selectively allodepleted stem cell grafts would lead to improved antiviral immunity after transplantation. The retention of immunosuppressive CD4(+) CD25(+) T-regulatory cells could lead to more ordered immune reconstitution and further suppress alloreactive responses after transplantation. |
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