Abstract
BackgroundAdoptive transfer of CMV-specific T cells has shown promising results in preventing pathological effects caused by opportunistic CMV infection in immunocompromised patients following allogeneic hematopoietic stem cell transplantation. The majority of studies have used steady-state leukapheresis for CMV-reactive product manufacture, a collection obtained prior to or months after G-CSF mobilization, but the procurement of this additional sample is often not available in the unrelated donor setting. If the cellular product for adoptive immunotherapy could be generated from the same G-CSF mobilized collection, the problems associated with the additional harvest could be overcome. Despite the tolerogenic effects associated with G-CSF mobilization, recent studies described that CMV-primed T cells generated from mobilized donors remain functional.MethodsMHC-multimers are potent tools that allow the rapid production of antigen-specific CTLs. Therefore, in the present study we have assessed the feasibility and efficacy of CMV-specific CTL manufacture from G-CSF mobilized apheresis using MHC-multimers.ResultsCMV-specific CTLs can be efficiently isolated from G-CSF mobilized samples with Streptamers and are able to express activation markers and produce cytokines in response to antigenic stimulation. However, this anti-viral functionality is moderately reduced when compared to non-mobilized products.ConclusionsThe translation of Streptamer technology for the isolation of anti-viral CTLs from G-CSF mobilized PBMCs into clinical practice would widen the number of patients that could benefit from this therapeutic strategy, although our results need to be taken into consideration before the infusion of antigen-specific T cells obtained from G-CSF mobilized samples.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0515-z) contains supplementary material, which is available to authorized users.
Highlights
Adoptive transfer of CMV-specific T cells has shown promising results in preventing pathological effects caused by opportunistic CMV infection in immunocompromised patients following allogeneic hematopoietic stem cell transplantation
Streptamer technology avoids the strict requirements associated with advanced therapy medicinal product (ATMP) manufacture, due to minimal manipulation of direct selection [12] and holds great promise in the unrelated donor setting, widening the clinical application of this fast and simple methodology [13,14,15]. In this present study we evaluated the feasibility of generating therapeutic CMV-reactive cytotoxic T cells (CTLs) using Streptamers from granulocyte-colony stimulating factor (G-CSF) treated donor samples, and were able to show that CMV-specific T cells directly selected from G-CSF mobilized samples are highly functional, their potential is slightly reduced when compared to non-mobilized CMV-specific Cytotoxic T cell (CTL) (CMV-CTLs)
Cytomegalovirus-specific cytotoxic T cell (CMV-CTL) were isolated from original samples using Streptamer and the purity of the obtained product was determined as the percentage of ST+ cells in the product, whereas the yield was defined as the absolute number of ST+ cells present in the positive fraction as a proportion of the absolute number of ST+ cells in the sample prior to isolation (Fig. 1a, 1b)
Summary
Adoptive transfer of CMV-specific T cells has shown promising results in preventing pathological effects caused by opportunistic CMV infection in immunocompromised patients following allogeneic hematopoietic stem cell transplantation. The majority of studies that generated virus-specific T cells have used non-mobilized peripheral blood mononuclear cells (PBMCs) isolated from an additional leukapheresis collection from the original allo-HSCT donor, different to that of the peripheral blood stem cell (PBSCs) collection performed after granulocyte-colony stimulating factor (G-CSF; Filgrastim) treatment. This additional leukapheresis harvest, apart from increasing the cost of the procedure and the discomfort caused to the donor, can be difficult to obtain in the unrelated donor setting where donor refusal or logistical and scheduling difficulties can prevent collection [6,7,8]. Manufacture of virus-specific T cells from the original G-CSF mobilized collection could potentially overcome the difficulties associated with procurement of a second apheresis
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