We have found that migratory dendritic cells (DCs) from tumor-draining lymph nodes in tumor-bearing mice are defective in soluble antigen endocytosis and are unable to effectively stimulate antigen-specific CD4 T cells. We will use tumors expressing the model antigen Ovalbumin to examine DC function and will assess the ability of these DCs to stimulate Ovalbumin-specific CD4 T cells that are necessary to stimulate anti-Ovalbumin CD8 anti-tumor responses. We also plan to examine the extent to which lymph node DCs are poisoned by exposure to the immunosuppressive environment of the tumor and will attempt to identify tumor-derived factors that suppress DC function.