Ex Vivo Expansion of Human CD8+ T Cells Using Autologous CD4+ T Cell Help

Abstract

BackgroundUsing in vivo mouse models, the mechanisms of CD4+ T cell help have been intensively investigated. However, a mechanistic analysis of human CD4+ T cell help is largely lacking. Our goal was to elucidate the mechanisms of human CD4+ T cell help of CD8+ T cell proliferation using a novel in vitro model.Methods/Principal FindingsWe developed a genetically engineered novel human cell-based artificial APC, aAPC/mOKT3, which expresses a membranous form of the anti-CD3 monoclonal antibody OKT3 as well as other immune accessory molecules. Without requiring the addition of allogeneic feeder cells, aAPC/mOKT3 enabled the expansion of both peripheral and tumor-infiltrating T cells, regardless of HLA-restriction. Stimulation with aAPC/mOKT3 did not expand Foxp3+ regulatory T cells, and expanded tumor infiltrating lymphocytes predominantly secreted Th1-type cytokines, interferon-γ and IL-2. In this aAPC-based system, the presence of autologous CD4+ T cells was associated with significantly improved CD8+ T cell expansion in vitro. The CD4+ T cell derived cytokines IL-2 and IL-21 were necessary but not sufficient for this effect. However, CD4+ T cell help of CD8+ T cell proliferation was partially recapitulated by both adding IL-2/IL-21 and by upregulation of IL-21 receptor on CD8+ T cells.ConclusionsWe have developed an in vitro model that advances our understanding of the immunobiology of human CD4+ T cell help of CD8+ T cells. Our data suggests that human CD4+ T cell help can be leveraged to expand CD8+ T cells in vitro.

CD8 T Cell Priming in the Presence of IFN-α Renders CTLs with Improved Responsiveness to Homeostatic Cytokines and Recall Antigens: Important Traits for Adoptive T Cell Therapy

“…Several reasons may account for such superiority: 1) low-differentiation state with naive-like features of the transferred CD8 T cells, which may favor their replication on infusion; 2) heightened capacity to mount a recall response; 3) enhanced responsiveness to IL-15 and IL-7, which extends the in vivo persistence; and 4) readiness to respond to IL-2 and IL-21, which may enable transferred cells to receive help from CD4 T cells (6). Even though in our experimental approach the adoptive T cell transfer per se only delayed tumor growth, we believe that IFN-a-primed CD8 T cells, in combination with other supportive treatments (e.g., therapeutic vaccination and/or administration of cytokines together with nonmyeloablative chemotherapy or irradiation), would lead to an enhanced therapeutic effect.…”

“…CD4 T cells can provide help to CD8 T cells through interplays between CD4 T cells and DC and CD4 and CD8 T cells. This takes place via cell-to-cell interactions, mediated by CD40/ CD40L (5, 7), and by means of paracrine cytokines, such as IL-2 and IL-21 (6). IFNs-I may bypass the requirement of CD4 T cell help for the induction of a CTL response by delivering maturation signals to DC, influencing the degree of Ag presentation and costimulation (31).…”

Specific Roles of Each TCR Hemichain in Generating Functional Chain-Centric TCR

“…Biotinylated HLA-A2/peptide monomers were purchased from ProImmune, multimerized in-house using SA-PE and SA-APC, and utilized to stain antigen-specific T cells as described previously (20, 37, 44, 45). A2/HIV multimer was always used as a control.…”

Toward precision manufacturing of immunogene T-cell therapies

“…More recently, K562 cells engineered to express a membrane-bound form of anti-CD3 monoclonal antibody (mAb) (mOKT3) and additional co-stimulatory molecules (CD80 and CD83) were shown to induce robust T-cell activation [69,70].…”