Induction of human tumor‐loaded dendritic cells

Abstract

A preferred anti-cancer vaccine would be tumor-specific, simple to rapidly construct and safe to administer. It would permit immunization against a spectrum of the tumor's distinctive antigens, without requiring their prior identification. Toward these goals, we describe a modification of standard extracorporeal photopheresis (ECP) which initiates, within a single day, both monocyte-to-dendritic cell (DC) differentiation and malignant cell apoptosis. The transition of mono-cytes to immature DCs was identified by the expression of cytoplasmic CD83 and membrane CD36 in the absence of membrane CD14 staining, as well as induction of membrane CD83 expression. Differentiating DCs were avidly phagocytic and engulfed apoptotic malignant T cells. Differentiating DCs were capable of stimulating significant proliferation of normal alloreactive lymphocyte responders, indicting increased expression of membrane MHC class II molecules. This approach provides a clinically practical means of developing tumor-loaded cells that have initiated the transition to DCs without the requirement of exogenous cytokines, excessive cellular manipulation or isolation. Construction of DC vaccines using this methodology can be generalized to other diseases and may offer a novel approach for improved cancer immunotherapy.

Sézary syndrome patients demonstrate a defect in dendritic cell populations: effects of CD40 ligand and treatment with GM-CSF on dendritic cell numbers and the production of cytokines

“…51 All participating patients in this study were treated with extracorporeal photopheresis (ECP). In this regard, it is important to stress that Berger et al 58 have demonstrated the potent capacity of ECP treatment to rapidly induce the differentiation of monocytes into large numbers of functional dendritic cells. This effect likely represents one of the most important mechanistic aspects of ECP therapy; the end result is the enhanced processing of apoptotic malignant T cells by the expanded dendritic cell population, leading to a more efficient "immunization" process against the tumor cells.…”

Cutaneous T‐cell lymphoma: 2011 update on diagnosis, risk‐stratification, and management

“…Psoralen covalently binds and crosslinks DNA following UVA exposure, leading to the induction of apoptosis in the majority of treated lymphocytes by multiple mechanisms involving bcl-2 family members, disruption of the mitochondrial membrane potential and extrinsic cell death pathways [303][304][305]. In contrast, ECP leads to monocyte activation, including significant changes in gene expression [306], and dendritic cell differentiation, which is thought to culminate in enhanced antigen presentation and the initiation of a host immune response [307]. In hopes of prolonging the exposure time between monocyte-derived dendritic cells and malignant lymphocytes undergoing apoptosis, investigators have developed a modified ECP protocol (i.e., ''transimmunization'') whereby blood products are incubated overnight following UVA irradiation and before patient infusion [308].…”

Dendritic cells loaded with apoptotic tumour cells induce a stronger T-cell response than dendritic cell–tumour hybrids in B-CLL

“…Irradiated cells were resuspended in the medium and incubated at 371C with 5% CO 2 for 24 h. The rate of apoptosis was analysed using annexin-V FITC apoptosis detection kit (Annexins Research, PharMingen, BD, USA) and 7AAD (PharMingen, BD) using flow cytometry. 1 At the end of 24 h of culture, apoptotic cells were spun down, washed and added at a ratio of 1:2 to immature DC. The cells were cocultured for an additional 24 h. Following the initial culture to allow endocytosis of apoptotic bodies, TNFa (20 ng/ ml) was added and cultured for an additional 36 h for maturation of DC.…”

“…Presentation of antigens by APC is necessary as tumour cells themselves usually lack the accessory molecules required for the induction and expansion of cytolytic T-cells that recognise tumour antigens in MHC class Iand II-restricted manner. 1 Dendritic cells (DC) possess the unique ability to efficiently present antigens to naïve T-cells and are a key player in the primary immune response.…”