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Abstract
We have shown in ex vivo studies in donor bone marrow-infused kidney transplant recipients, that chimeric cells of either donor or recipient origin taken from the recipient's bone marrow down-regulated the recipient's cellular immune responses. In the present study, we have now induced regulatory T cells from peripheral blood mononuclear cells (PBMC) of renal transplant recipients or laboratory volunteers by multi-stimulation with autologous immature dendritic cell (iDC) enriched populations derived from either bone marrow cells (BMC) of the (immunosuppressed) kidney transplant recipients or PBMC of the laboratory volunteers (i.e., ibDC and ipDC, respectively). These regulatory T cells, induced by ibDC and ipDC, were autoreactive and designated as TAb and TAp with similar phenotypes and functional profiles. They were largely CD4 + CD25high, CD45RA low and CD45RO high, and uniformly expressed intracellular CTLA-4, and message of IL-4, IL-10, Foxp3, and differentially expressed TGFβ. Their proliferative responses to autologous mature dendritic stimulating cells (mDC) were ∼two-fold stronger than to allogeneic mDC, and to allogeneic mDC were significantly lower than those of (control) autologous TPBL, suggesting an anergic state. TAb and TAp were not cytotoxic to autologous cells expressing Epstein-Barr virus (EBV) antigens, but were able to inhibit (regulate) the effector phase of this TPBL response to both autologous and allogeneic EBV lymphoblasts. This regulation appeared to require cell-to-cell contact.
| ABBREVIATIONS | ||
| APC: | = | Antigen presenting cells |
| BMC: | = | Bone marrow cells |
| DC: | = | Dendritic cells |
| EBV: | = | Epstein–Barr virus |
| FOXP3: | = | Forkhead box protein P3 gene |
| GM-CSF: | = | Granulocyte macrophage-colony stimulating factor |
| ibDC: | = | Immature BMC-derived dendritic cells |
| iDC: | = | Immature dendritic cells |
| ipDC: | = | Immature PBMC-derived dendritic cells |
| mDC: | = | Mature dendritic cells |
| MLDC: | = | Mixed lymphocyte dendritic cell |
| PBL: | = | Peripheral blood lymphocytes |
| PBMC: | = | Peripheral blood mononuclear cells |
| TAb: | = | Autoreactive T cell lines derived from cultures with ibDC |
| TAp: | = | Autoreactive T cell lines derived from cultures with ipDC |
| TPBL: | = | Controls for TA cultured without immature dendritic cell stimulation |
| Tregs: | = | Regulatory T cells |