Dendritic cells (DCS) are highly specialized bone marrow-derived antigen presenting cells (APCs) which function as potent stimulating cells for T- lymphocyte-mediated immune responses. Dendritic cell-based immunotherapy is an emerging treatment strategy involving ex vivo expansion and reinfusion of antigen-pulsed DCS into human patients to vaccinate against cancer or infectious diseases. A major limitation in this approach has been the capability to generate sufficient quantities of functional DCS for effective patient therapy. The primary objective of the proposed studies is to develop and implement a unique process for ex vivo expansion, differentiation, tumor antigen-loading and harvest of DCS in a continuously perfused clinical-scale bioreactor system. The hypothesis that continuous single-pass medium exchange will enable enhanced production of functional DCS at high density in Aastrom's Cell Production System (CPS) will be tested. The Phase II program will focus on optimization and full automation of the process in compliance with GMP regulations. The automated system will be tested in clinical trials to assess the safety and efficacy of dendritic cells produced in the CPS for human carcino-embryonic antigen (CEA-specific cancer therapy. An automated clinical scale bioreactor system would enable efficient production of highly functional dendritic cells as a superior APC type for cancer immunotherapy. PROPOSED COMMERCIAL APPLICATION: A closed, automated, GMP system for dendritic cell expansion, differentiation, antigen-loading and harvest would be of great value for immunotherapy of cancer and infectious diseases. The existing methods for dendritic cell expansion involve multiple open process steps with associated costs in equipment and labor. The development of a CPS-based DC expansion process will enable widespread application of successful dendritic cell-based therapies in a reliable and cost-effective fashion.