Programming of Donor T Cells Using Allogeneic Delta-like Ligand 4-Positive Dendritic Cells to Reduce Gvhd but Retain GVL Activity

• Published in: Blood 2015-12, Vol.126 (23), p.233-233
• Main Authors: Mochizuki, Kazuhiro, Meng, Lijun, Mochizuki, Izumi, Tong, Qing, He, Shan, Liu, Yongnian, Purushe, Janaki, Sun, Hongxing, Fung, Henry, Zaidi, Raza, Reshef, Ran, Blazar, Bruce R., Yagita, Hideo, Mineishi, Shin, Zhang, Yi
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V126.23.233.233

Host antigen-presenting cells (APCs) are critical for inducing a potent graft-versus-leukemia (GVL) response after allogeneic hematopoietic stem-cell transplantation (allo-HSCT). In this setting, host APCs activate donor T cells to become effector T cells that recognize and react to antigens in malignant cells. However, alloreactive T cells also mediate graft-versus-host disease (GVHD), which causes significant morbidity and mortality after allo-HSCT. Many studies suggest that if alloreactive T cells have reduced capacity to expand in local tissues, they will be unable to trigger severe GVHD. Thus, it is possible that host APC induction of qualitative changes in donor T cells can potentially modify their anti-host toxicities while retaining the GVL effect. Here we report the establishment of a cellular programming approach that reduces the GVHD toxicity of donor T cells using host dendritic cells (DCs) that express high levels of Dll4 (named Dll4hi DCs). We have previously identified inflammatory Dll4hi DCs. They occurred in HSCT mice early during GVHD induction and had a greater ability than Dll4-negative DCs to induce IFN-γ and IL-17 in alloantigen-activated T cells. However, only approximately 0.03 X 105 Dll4hi DCs were recovered from one HSCT mouse. To provide adequate numbers of Dll4hi DCs for therapeutic translation, we developed a novel culture system capable of producing large number of Dll4hi DCs (about 100.0 X 105) from the bone marrow (BM) of one mouse using Flt3L and the TLR agonists lipopolysaccharide (LPS) and R848, which activate TLR4 and TLR7/8, respectively. Dll4hi DCs showed significantly different phenotype as compared to conventional DCs derived from GM-CSF-stimulated BM cells (named GM-DCs), as evidenced by expressing higher levels of Dll4, Ifnb, Il4, Il6 and Ido, and producing lower levels of iNOS and arginase I. When cultured with C57BL/6 (B6) mouse CD4+ T cells (H2b) at a T cell: DC ratio of 4:1 for 5 days, BALB/c mouse Dll4hi DCs (H2d) induced 3- to 5-fold more in frequency of alloreactive effector T cells producing high levels of IFN-γ and IL-17 compared to GM-DCs. Following transfer, allogeneic Dll4hi DC-induced CD4+ T cells were unable to mediate severe GVHD in BALB/c recipients, with all of them surviving 60 days after allo-HSCT. In contrast, both unstimulated B6 CD4+ T cells and allogeneic GM-DC-induced B6 CD4+ T cells caused lethal GVHD in all BALB/c recipients, indicating that GM-DCs could not be used for reducing the GVHD t