Clinically applicable CD34+-derived blood dendritic cell subsets exhibit key subset-specific features and potently boost anti-tumor T and NK cell responses

Abstract

Allogeneic stem cell transplantation (alloSCT), following induction chemotherapy, can be curative for hemato-oncology patients due to powerful graft-versus-tumor immunity. However, disease recurrence remains the major cause of treatment failure, emphasizing the need for potent adjuvant immunotherapy. In this regard, dendritic cell (DC) vaccination is highly attractive, as DCs are the key orchestrators of innate and adaptive immunity. Natural DC subsets are postulated to be more powerful compared with monocyte-derived DCs, due to their unique functional properties and cross-talk capacity. Yet, obtaining sufficient numbers of natural DCs, particularly type 1 conventional DCs (cDC1s), is challenging due to low frequencies in human blood. We developed a clinically applicable culture protocol using donor-derived G-CSF mobilized CD34+ hematopoietic progenitor cells (HPCs) for simultaneous generation of high numbers of cDC1s, cDC2s and plasmacytoid DCs (pDCs). Transcriptomic analyses demonstrated that these ex vivo-generated DCs highly resemble their in vivo blood counterparts. In more detail, we demonstrated that the CD141+CLEG9A+ cDC1 subset exhibited key features of in vivo cDC1s, reflected by high expression of co-stimulatory molecules and release of IL-12p70 and TNF-α. Furthermore, cDC1s efficiently primed alloreactive T cells, potently cross-presented long-peptides and boosted expansion of minor histocompatibility antigen-experienced T cells. Moreover, they strongly enhanced NK cell activation, degranulation and anti-leukemic reactivity. Together, we developed a robust culture protocol to generate highly functional blood DC subsets for in vivo application as tailored adjuvant immunotherapy to boost innate and adaptive anti-tumor immunity in alloSCT patients.

Saponin-based adjuvants enhance antigen cross-presentation in human CD11c+CD1c+CD5−CD163+conventional type 2 dendritic cells

“…For MiHA-specific T-cell expansion assays, cryopreserved PBMCs containing HA-1-specific CD8 + memory T cells from allogeneic stem cell transplantation patients were used. 61 All patient material was obtained in accordance with the Declaration of Helsinki and institutional guidelines and regulations (CMO 2012/064). The different DC populations were isolated, as described above, from HLA-A*02:01 + buffy coats from healthy donors (Sanquin, Nijmegen, The Netherlands) and typed HA-1 − with PCR to prevent endogenous expression of HA-1 by the DCs.…”

Dendritic Cell Subsets in Melanoma: Pathophysiology, Clinical Prognosis and Therapeutic Exploitation

“…Due to the low proportions of circulating cDC1s, this subtype of DC has not yet been used as a vector for DC vaccines, despite their high potential to induce cytotoxic T-responses. However, it has been made possible to produce, from CD34 + precursors, large number of cDC1s capable of cross-presenting long peptides to CD8 T-cells and activating NK cells, paving the way for the use of cDC1s for future vaccine approaches [ 161 ].…”

The Potential of Dendritic Cell Subsets in the Development of Personalized Immunotherapy for Cancer Treatment

“…The first step in DC vaccine development is obtaining a sufficient number of cells for further manipulations. Current approaches to generating DCs mainly focus on in vitro differentiation from CD14 + or CD34 + monocyte precursors [49][50][51][52] (Figure 2). This direction is driven by the fact that DCs, circulating in the body, are a small population of immune cells, and isolating them in the required quantity to achieve therapeutic effects is rather challenging.…”