A closed and single-use system for monocyte enrichment: potential for dendritic cell generation for clinical applications.
ABSTRACT This study evaluated the ability of a modified cell separator (Cobe Spectra Apheresis) system to isolate monocytes (MOs) by elutriation. The evaluation was performed in two independent international laboratories. The capacity of collected MOs to differentiate into dendritic cells (DCs) was also assessed.
MNCs from platelet apheresis residues were elutriated on a modified cell separator (Cobe Spectra Apheresis system) using a custom disposable set. Cells were separated according to their size and density. Recovery and purity of the collected cell product were evaluated by impedance counting and flow cytometry. DCs were differentiated in culture from the elutriated MOs and characterized by their surface markers and stimulatory capacity in a mixed WBC reaction assay.
Six apheresis mononuclear cell products were used by each laboratory. The separation was achieved in less than 1 hour. Collected MOs had the potential to differentiate into DCs.
The modified cell separator is an easy and fast device to obtain highly enriched MOs with a DC differentiation potential. The system is closed and employs a single-use disposable set and is more amenable to good tissue practice. This method could become a valuable tool for DC-based active immunotherapy.
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ABSTRACT: The discovery of tumor-associated antigens, which are either selectively or preferentially expressed by tumors, together with an improved insight in dendritic cell biology illustrating their key function in the immune system, have provided a rationale to initiate dendritic cell-based cancer immunotherapy trials. Nevertheless, dendritic cell vaccination is in an early stage, as methods for preparing tumor antigen presenting dendritic cells and improving their immunostimulatory function are continuously being optimized. In addition, recent improvements in immunomonitoring have emphasized the need for careful design of this part of the trials. Still, valuable proofs-of-principle have been obtained, which favor the use of dendritic cells in subsequent, more standardized clinical trials. Here, we review the recent developments in clinical DC generation, antigen loading methods and immunomonitoring approaches for DC-based trials.
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ABSTRACT: The majority of common cancers preferentially affect the older population. However, despite the recognized role of dendritic cells in cancer immunotherapy, relatively little is known about the consequence of aging on these important cells. Recent studies have revealed that dendritic cells from old hosts exhibit significant functional defects at multiple levels. These changes may provide a mechanistic basis for the disappointing results of dendritic cell-based immunotherapy in older cancer patients. There is clearly a need to improve our knowledge on how aging modulates these parameters to optimally exploit DC in anticancer vaccines.12/2008: pages 171-180;
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ABSTRACT: To initiate immune responses, dendritic cells follow a migratory route from their recruitment as sentinels into tissues, including solid tumors, then to secondary lymphoid organs where they contour the immune response. Migratory capacities and chemokine responsiveness are therefore key elements in dendritic cell immunobiology. Tumor-derived factors alter dendritic cell maturation and function and thus markedly affect dendritic cell trafficking and distribution. Tumor-mediated down-regulation or redirection of dendritic cell migration and homing may markedly alter a normal pattern of dendritic cell localization and thus induction of antitumor immunity in tumor-bearing hosts, and might also strongly inhibit the efficacy of dendritic cell vaccines. Improved understanding of the regulation of DC trafficking might offer new opportunities for therapeutic interventions to control immune responses. Given the current interest in applying dendritic cell-based immunotherapy to cancer treatment, an understanding of the molecular defects responsible for dysfunction of dendritic cell trafficking and biodistribution in cancer is essential for designing and testing the next generation of dendritic cell vaccines.12/2008: pages 271-289;