Human Cytomegalovirus Impairs the Function of Plasmacytoid Dendritic Cells in Lymphoid Organs

Human dendritic cells (DCs) are the main antigen presenting cells (APC) and can be divided into two main populations, myeloid and plasmacytoid DCs (pDCs), the latter being the main producers of Type I Interferon. The vast majority of pDCs can be found in lymphoid organs, where the main pool of all immune cells is located, but a minority of pDCs also circulate in peripheral blood. Human cytomegalovirus (HCMV) employs multiple mechanisms to evade the immune system. In this study, we could show that pDCs obtained from lymphoid organs (tonsils) (tpDCs) and from blood (bpDCs) are different subpopulations in humans. Interestingly, these populations react in opposite manner to HCMV-infection. TpDCs were fully permissive for HCMV. Their IFN-α production and the expression of costimulatory and adhesion molecules were altered after infection. In contrast, in bpDCs HCMV replication was abrogated and the cells were activated with increased IFN-α production and upregulation of MHC class I, costimulatory, and adhesion molecules. HCMV-infection of both, tpDCs and bpDCs, led to a decreased T cell stimulation, probably mediated through a soluble factor produced by HCMV-infected pDCs. We propose that the HCMV-mediated impairment of tpDCs is a newly discovered mechanism selectively targeting the host's major population of pDCs residing in lymphoid organs

Allogeneic donor split skin grafts for treatment of refractory ulcers in cutaneous chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation—a retrospective analysis on seven patients

Refractory skin ulcers due to severe chronic graft-versus-host disease (cGVHD) remain to be associated with significant morbidity and mortality.We performed an allogeneic donor skin transplantation in seven adult patients after allogeneic hematopoietic stem cell transplantation for cGVHD-associated refractory skin ulcers. While four patients received a split skin graft (SSG), in one patient, a full thickness skin graft for two small refractory ulcers of the ankle was performed, and one patient received in vitro expanded donor keratinocyte grafts derived from hair roots of the original unrelated donor. In one additional patient, a large deep fascial defect of the lower leg was covered with an autologous greater omentum free graft before coverage with an allogeneic SSG. An additional patient was treated with an autologous scrotal skin graft for a refractory ulcer associated with deep sclerosis of cGVHD after unrelated donor transplantation.All skin grafts engrafted and resulted in permanent coverage of the grafted ulcers without any signs of immunological mediated damage. In the patient receiving in vitro expanded keratinocyte grafts, two localized ulcers were permanently covered by donor skin while this approach failed to cover extensive circular ulcers of the lower legs.Allogeneic donor skin grafts are a valuable treatment option in refractory ulcers due to cGVHD but are restricted mainly to related donors while keratinocyte grafts from unrelated donors remain experimental. In male patients lacking a related donor, autologous scrotal skin graft may be an alternative option

Progressive multifocal leukoencephalopathy in a patient post allo-HCT successfully treated with JC virus specific donor lymphocytes

Background Progressive multifocal leukoencephalopathy is a demyelinating CNS disorder. Reactivation of John Cunningham virus leads to oligodendrocyte infection with lysis and consequent axonal loss due to demyelination. Patients usually present with confusion and seizures. Late diagnosis and lack of adequate therapy options persistently result in permanent impairment of brain functions. Due to profound T cell depletion, impairment of T-cell function and potent immunosuppressive factors, allogeneic hematopoietic cell transplantation recipients are at high risk for JCV reactivation. To date, PML is almost universally fatal when occurring after allo-HCT. Methods To optimize therapy specificity, we enriched JCV specific T-cells out of the donor T-cell repertoire from the HLA-identical, anti-JCV-antibody positive family stem cell donor by unstimulated peripheral apheresis [1]. For this, we selected T cells responsive to five JCV peptide libraries via the Cytokine Capture System technology. It enables the enrichment of JCV specific T cells via identification of stimulus-induced interferon gamma secretion. Results Despite low frequencies of responsive T cells, we succeeded in generating a product containing 20 000 JCV reactive T cells ready for patient infusion. The adoptive cell transfer was performed without complication. Consequently, the clinical course stabilized and the patient slowly went into remission of PML with JCV negative CSF and containment of PML lesion expansion. Conclusion We report for the first time feasibility of generating T cells with possible anti-JCV activity from a seropositive family donor, a variation of virus specific T-cell therapies suitable for the post allo transplant setting. We also present the unusual case for successful treatment of PML after allo-HCT via virus specific T-cell therapy

Transfer of minimally manipulated CMV-specific T cells from stem cell or third-party donors to treat CMV infection after allo-HSCT

Cytomegalovirus (CMV) infection is a common, potentially life-threatening complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT). We assessed prospectively the safety and efficacy of stem cell-donor-or third-party-donor-derived CMV-specific T cells for the treatment of persistent CMV infections after allo-HSCT in a phase I/IIa trial. Allo-HSCT patients with drugrefractory CMV infection and lacking virus-specific T cells were treated with a single dose of ex vivo major histocompatibility complex-Streptamer-isolated CMV epitope-specific donor T cells. Forty-four allo-HSCT patients receiving a T-cell-replete (D+ repl; n = 28) or T-cell-depleted (D+ depl; n = 16) graft from a CMV-seropositive donor were screened for CMV-specific T-cell immunity. Eight D+ depl recipients received adoptive T-cell therapy from their stem cell donor. CMV epitope-specific T cells were well supported and became detectable in all treated patients. Complete and partial virological response rates were 62.5% and 25%, respectively. Owing to longsome third-party donor (TPD) identification, only 8 of the 57 CMV patients transplanted from CMV-seronegative donors (D-) received antigen-specific T cells from partially human leukocyte antigen (HLA)-matched TPDs. In all but one, TPD-derived CMV-specific T cells remained undetectable. In summary, adoptive transfer correlated with functional virus-specific T-cell reconstitution in D+ depl patients. Suboptimal HLA match may counteract expansion of TPD-derived virus-specific T cells in D-patients