Generation of HCMV-specific T-cell lines from seropositive solid-organ-transplant recipients for adoptive T-cell therapy.

Chronically immunosuppressed patients, like solid-organ-transplant (SOT) recipients, are at increased risk for severe human cytomegalovirus (HCMV) infection. Despite the availability of effective antiviral drugs, lasting control of remaining viruses is dependent on an effective T-cell immunity. So in some patients conventional antiviral therapy cannot control the infection and prolonged virostatic therapy is limited by its side effects and the development of viral resistance. Selective reconstitution of cellular immunity by adoptive transfer of HCMV-specific T cells derived from healthy donors is a safe and effective approach in hematopoietic stem cell transplant recipients. The aim of this study was to determine whether functional HCMV-specific T cells can also be generated from chronically immunosuppressed patients. Autologous CD4+/8+ T-cell lines directed against the HCMV protein IE-1 were generated from the peripheral blood of SOT patients using a recently developed modular protocol easily applicable to good-manufacturing-practice conditions. T-cell lines from SOT patients showed similar features as cells from healthy donors regarding phenotype, functionality (HCMV-specific killing, gene expression pattern, and cytokine secretion), IE-1 epitope recognition, and dominance of distinct T-cell receptor V beta families. Most importantly, this protocol also allowed the generation of T-cell lines from immunosuppressed patients with HCMV infection/chronic HCMV disease. Our data suggest the potential of this autologous approach for the treatment of SOT recipients suffering from HCMV infection/disease poorly responding to virostatic therapy.

Generation of EBV-specific T cells for adoptive immunotherapy: a novel protocol using formalin-fixed stimulator cells to increase biosafety.

Adoptive immunotherapy with in vitro generated Epstein-Barr virus (EBV)-specific T cells is a safe and effective treatment in patients with EBV-related complications after transplantation. More frequent use of EBV-specific T cells is held back by their cost and time-intensive generation under good manufacturing practice (GMP) conditions. Currently, EBV-specific T cells are produced by repetitive stimulation of peripheral blood mononuclear cells with EBV-infected lymphoblastoid cell lines (LCLs), a protocol that requires several open GMP-handling steps. The aim of the present study was to improve T-cell generation under GMP conditions. We introduce a novel generation protocol that replaces repetitive with short-term LCL stimulation of PMBCs. Vital and formalin-fixed LCLs were used to further increase biosafety. Stimulated T cells were selected by the clinically approved cytokine secretion assay followed by nonspecific expansion. Sufficient numbers of EBV-specific T-cell lines were generated with all protocols. Specific recognition and killing of EBV-infected targets was found and was independent of the generation protocol applied. The novel protocol based on formalin-fixed cells, selection, and expansion reduced open GMP-handling steps and increased biosafety. Furthermore, fixation will allow the use of transgenic LCLs (eg, with cytomegalovirus or tumor antigens) and thereby facilitate the generation of antigen-specific T cells directed against pathogens other than EBV.

Digital NFATc2 activation per cell transforms graded T cell receptor activation into an all-or-none IL-2 expression.

The expression of interleukin-2 (IL-2) is a key event in T helper (Th) lymphocyte activation, controlling both, the expansion and differentiation of effector Th cells as well as the activation of regulatory T cells. We demonstrate that the strength of TCR stimulation is translated into the frequency of memory Th cells expressing IL-2 but not into the amount of IL-2 per cell. This molecular switch decision for IL-2 expression per cell is located downstream of the cytosolic Ca2+ level. Here we show that in a single activated Th cell, NFATc2 activation is digital but NF-kappaB activation is graded after graded T cell receptor (TCR) signaling. Subsequently, NFATc2 translocates into the nucleus in an all-or-none fashion per cell, transforming the strength of TCR-stimulation into the number of nuclei positive for NFATc2 and IL-2 transcription. Thus, the described NFATc2 switch regulates the number of Th cells actively participating in an immune response.