Virus-specific T cells have been shown to cross-react with allogeneic HLA (allo-HLA) at a clonal level. However, the impact of a single virus on the allorepertoire has never been investigated at... Show moreVirus-specific T cells have been shown to cross-react with allogeneic HLA (allo-HLA) at a clonal level. However, the impact of a single virus on the allorepertoire has never been investigated at the polyclonal level.We made an inventory of the incidence and specificity of allo-HLA-cross-reactive-virus-specific CD8(+) T cells in 24 healthy individuals. T cells were stained for 25 virus-specific tetramers, and mixed-lymphocyte reactions were performed against a panel of HLA-typed allostimulators. Allospecificity was confirmed by IFN gamma-ELISA using T-cell clones against a panel of HLA-typed cell-lines.The polyclonal immune repertoire directed against CMV alone was associated with a memory response against six allo-HLA molecules. Besides, a single allostimulator activated memory T-cell responses with multiple viral specificities.Concluding, a single virus can substantially broaden the allo-HLA memory T-cell repertoire. This study only looked at CMV- and EBV-specific T cells, whereas the immune repertoire consists of T cells directed against many different viruses. Hence, transplant patients receiving an HLA-mismatched graft may already express a poly clonal repertoire of anti-donor-memory T cells before transplantation. Show less
Zwan, A. van der; Meer-Prins, E.M.W. van der; Miert, P.P.M.C. van; Heuvel, H. van den; Anholts, J.D.H.; Roelen, D.L.; ... ; Heidt, S. 2018
Virus-specific T cells can recognize allogeneic HLA (allo-HLA) through TCR cross-reactivity. The allospecificity often differs by individual (private cross-reactivity) but also can be shared by... Show moreVirus-specific T cells can recognize allogeneic HLA (allo-HLA) through TCR cross-reactivity. The allospecificity often differs by individual (private cross-reactivity) but also can be shared by multiple individuals (public cross-reactivity); however, only a few examples of the latter have been described. Because these could facilitate alloreactivity prediction in transplantation, we aimed to identify novel public cross-reactivities of human virus-specific CD8(+) T cells directed against allo-HLA by assessing their reactivity in mixed-lymphocyte reactions. Further characterization was done by studying TCR usage with primer-based DNA sequencing, cytokine production with ELISAs, and cytotoxicity with 51 chromium-release assays. We identified three novel public allo-HLA cross-reactivities of human virus-specific CD8(+) T cells. CMV B35/IPS CD8(+) T cells cross-reacted with HLA-B51 and/or HLA-B58/B57 (23% of tetramer-positive individuals), FLU A2/GIL (influenza IMP[58-66] HLA-A* 02: 01/GILGFVFTL) CD8(+) T cells with HLA-B38 (90% of tetramer-positive individuals), and VZV A2/ALW (varicella zoster virus IE62[593-601] HLA-A*02:01/ALWALPHAA) CD8(+) T cells with HLA-B55 (two unrelated individuals). Cross-reactivity was tested against different cell types including endothelial and epithelial cells. All cross-reactive T cells expressed a memory phenotype, emphasizing the importance for transplantation. We conclude that public allo-HLA cross-reactivity of virus-specific memory T cells is not uncommon and may create novel opportunities for alloreactivity prediction and risk estimation in transplantation. Show less
Background. Blood transfusion (BT) may elicit both harmful and beneficial immune responses against a subsequent organ graft. Immune parameters of a single, nonleukocyte-depleted BT were... Show moreBackground. Blood transfusion (BT) may elicit both harmful and beneficial immune responses against a subsequent organ graft. Immune parameters of a single, nonleukocyte-depleted BT were investigated in two groups: non-human leukocyte antigen (HLA)-sensitized recipients with a one-HLA-DR matched donor (protocolled BT [PBT]) and females with previous exposure to HLA alloantigens through pregnancy (donor-specific transfusion [DST]). Methods. Thirty-five percent of DST recipients and 9.5% of PBT recipients developed HLA antibodies after BT. Phenotypic and functional analyses were performed in pre-BT, 2 weeks post-BT, and more than 10 weeks post-BT samples (PBT: n=10; DST: n=14). Result. The number of donor-reactive interferon-gamma-producing memory T cells increased 2 weeks post-BT, but only in the DST group, increased frequencies persisted beyond 10 weeks (P<0.004). In the DST recipients, the proportion of natural killer cells (CD3(-)CD56(+)) significantly increased after BT (P=0.01), whereas in PBT recipients, the proportion of regulatory T cells (CD4(+)CD25(+)Foxp3(+)CD127(low)) significantly increased at 2 weeks post-BT (P=0.039). Microarray analysis confirmed increased activity of genes involved in function of natural killer cells, T cells, and B cells in DST recipients and increased expression of immuneregulatory genes (galectin-1, Foxo3a, and follistatin-like 3) in PBT recipients. Galectin-1 expression by quantitative polymerase chain reaction was significantly enhanced in peripheral blood cells after PBT (P<0.05). Conclusion. Decreased immune effector mechanisms combined with an increased immune regulatory cell signature after HLA-DR-matched BT in nonsensitized patients is in line with clinical observations of improved outcome of a subsequent graft. Previous sensitization, however, may lead to HLA antibody formation and prolonged donor-specific memory T-cell reactivity after BT. Show less
