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Donor lymphocyte infusion (DLI) - Derived T cell responses in vivo: Differential fate of CD4(+) and CD8(+) T cells

To probe the mechanisms that regulate the fate of DLI-derived CD4 + and CD8 + T cells and their responses to host antigens, we utilized a MHC-matched minor antigen mismatched model in which DLI were administered to stable allogeneic chimeras expressing differential levels of model antigen. Transgenic mice with ubiquitous (HA104) or pancreas-restricted (Ins-HA) expression of hemagglutinin (HA) as model antigen served as recipients, while the MHC-matched minor-antigen-mismatched T cell receptor (TCR) transgenic mice containing H-2K d restricted CD8 + (CL-4) or I-E d restricted CD4 + T cells (6.5) specific for HA peptide served as a source of antigen-specific lymphocytes. After lethal conditioning, HA104, Ins-HA on BALB/c (H2 d) background and control BALB/c mice received bone marrow from MHC-compatible B10.D2 (H-2 d) donors, followed by DLI three weeks later. DLI consisted of 2 x 10 7 B10.D2 splenocytes spiked with 3 x 10 6 TCR transgenic CL-4 or 6.5 T cells. Differential expression of the Thy 1.1 antigen on transgenic T cells and CFSE labeling were used for in vivo monitoring of CL-4 and 6.5 T cell fate and proliferation pattern. In vivo findings were also correlated with functional testing of the transgenic T cell capacity to respond to their cognate antigen at designated time points. CL-4 T cells adoptively transferred to the HA104 chimeras divided rapidly and by day 6, their level of expansion in the spleen (52x10 6 ; n=3/mice per group) was 12 and 7 folds higher than in the Ins-HA and non-transgenic control BALB/c chimera, respectively. Following that time point, the total amount of CL-4 T cells in all three groups of chimeras progressively declined. In vitro studies with cognate peptide at days 19 and 24 post-transfer revealed that the remaining CL-4 T cells in the HA104 chimeras were anergic in comparison to cells from the other two groups that all vigorously proliferated and produced interferon, although in Ins-HA mice decreased amounts were present on a per cell basis. 6.5 cells also underwent rapid proliferation and expansion in the HA104 chimeras (42.7x10 6 cells/spleen) by day 6 post-transfer with a level of expansion 21 and 22 fold higher than in the Ins-HA and non-transgenic control BALB/c chimeras, respectively. In vitro assessment of 6.5 cell function retrieved from the HA104 chimeras revealed that they were profoundly anergic and had acquired a regulatory function as determined by their ability to suppress in vitro proliferation of naive 6.5 cells. Results from the other two groups show that 6.5 T cells had undergone homeostatic proliferation with minimal expansion. However these cells exhibited in vitro hypoproliferative responses to the nominal antigen and at all time points secreted very low levels of IL-2, on a per cell basis. These data suggest the following: a) DLI-derived CD4 + and CD8 + T cells transferred to the allogeneic host have an intrinsically different fate as implied by the functional responses of Cl-4 and 6.5 T cells regardless of in vivo antigen recognition ; b) the ubiquitously expressed agonist antigen on hematopoietic cells has a direct role in inducing CD4 + cells with regulatory phenotype ; c) the distribution pattern of targeted antigens should be considered in selecting the targets for adoptive immunotherapy with antigen-specific CD8 + clones.

T cell response |experimental model |donor lymphocyte infusions

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