Priming of a Novel Subset of CD28+ Rapidly Expanding High-Avidity Effector Memory CTL by Post Maturation Electroporation-CD40L Dendritic Cells Is IL-12 Dependent

Abstract

Dendritic cell (DC)-based immunotherapeutics must induce robust CTL capable of killing tumor or virally infected cells in vivo. In this study, we show that RNA electroporated post maturation and coelectroporated with CD40L mRNA (post maturation electroporation (PME)-CD40L DC) generate high-avidity CTL in vitro that lyse naturally processed and presented tumor Ag. Unlike cytokine mixture-matured DC which induce predominantly nonproliferative effector memory CD45RA+ CTL, PME-CD40L DC prime a novel subset of Ag-specific CTL that can be expanded to large numbers upon sequential DC stimulation in vitro. We have defined these cells as rapidly expanding high-avidity (REHA) CTL based on: 1) the maintenance of CD28 expression, 2) production of high levels of IFN-γ and IL-2 in response to Ag, and 3) the demonstration of high-avidity TCR that exhibit strong cytolytic activity toward limiting amounts of native Ag. We demonstrate that induction of REHA CTL is dependent at least in part on the production of IL-12. Interestingly, neutralization of IL-12 did not effect cytolytic activity of REHA CTL when Ag is not limiting, but did result in lower TCR avidity of Ag-reactive CTL. These results suggest that PME-CD40L DC are uniquely capable of delivering the complex array of signals needed to generate stable CD28+ REHA CTL, which if generated in vivo may have significant clinical benefit for the treatment of infectious disease and cancer.

Immunogenicity of AGS-004 Dendritic Cell Therapy in Patients Treated During Acute HIV Infection

“…10,23,24 A second leukapheresis was collected before ATI for immune monitoring purposes. Autologous DCs were again co-electroporated with CD40 L RNA and GNVR, or with CD40 L RNA, and each individual antigen RNA or with CD40 L RNA and GFP RNA (DCs expressing green fluorescent protein (GFP) served as control DCs).…”

“…CD40 L is employed to maximize DC antigen presentation 9 and improve immunopotency, by inducing secretion of interleukin (IL)-12, a necessary cytokine for CD8 + T cell responses. 10,11 In this sub-study, we evaluated AGS-004 in participants who started ART during AHI, as immune-enhancing strategies may be particularly suited to these individuals. ART initiation during AHI can preserve HIV-1-specific CD4…”

Dendritic cells in cancer immunotherapy

“…Several combinations of stimuli (notably TLR ligands and CD40L) have been described to generate superior T-cell stimulatory/differentiation capacity in vitro (where migratory DC and their released products are forced against their nature to stay together with T cells in culture vessels), but too little is known whether this will translate in vivo into enhanced effectiveness [62][63][64][65][66][67][68][69][70]. One obstacle to clinical testing is that these reagents are often not available to the scientific community in GMP quality.…”

“…route [45]. We are also exploring DC transfected after maturation with an optimized CD40L mRNA, which results in DC that induce highly proliferative, inflammatory CTL in vitro [63,64]. Within the DC-THERA Network of Excellence (www.dc-thera.…”

Functional and Phenotypic Analysis of Two-Day Monocyte-Derived Dendritic Cells Suitable for Immunotherapy Purposes

“…Furthermore, substantial production of IFN-γ by specific CD4+ T cell in response to Tetanus Toxoid (TT) and in a Mixed Leukocyte Reaction (MLR), suggests that antigen presentation by 2d-stDCs to T cells can induce the secretion of IL-12p70 by the DCs necessary to facilitate the stimulation of Th1 immune responses [ Figure S4]. This is important if we consider that IL-12p70 production by DCs has become a key marker of competent DCs that will be used with immunotherapy purposes [53]. Recently, Mailliard et al [23], described a type I alpha DCs, using a modification of the standard cocktail by adding Type I/II interferons and Poly I:C in order to obtain mature DCs capable of producing high amounts of IL-12p70 and activate Th1 cells responses.…”