Activation of omental immune aggregates: a potential tumor therapy (131.37)

Abstract

Abstract Tumor metastasis within the peritoneal cavity is a concern for those diagnosed with cancers of peritoneal organs. A tissue implicated in this process is the omentum, which is composed of adipose tissue embedded with immune cell aggregates. We, and others have demonstrated that upon introduction of tumor cells into the peritoneal cavity, omental immune aggregates are the initial site of attachment. Due to their high vascularity, they provide an ideal microenvironment for tumor growth. Thus, treatment of peritoneal metastases often includes removal of the omentum. However, we hypothesize that stimulation of omental immune cells might result in reduced tumor growth. Our initial experiments demonstrate that injection of particles into the peritoneal cavity resulted in their uptake by macrophages present in the peritoneal fluid and rapid migration to immune aggregates. To determine if tumor antigens would result in effective immunity when bound to these aggregates, mice were immunized intraperitoneally with irradiated EMT6 tumor cells and later challenged with live EMT6/GFP cells. Omenta and peritoneal fluid were analyzed for the presence of memory CD8+ T cells and tumor cells. Our results show that immunization results in increased memory CD8+ T cells and decreased tumor burden on the omentum, indicating that omental immune cells are capable of responding against tumor cells. Further studies are being done to examine tumor burden in mice immunized after tumor establishment.