Intraperitoneal immunization prevents autologous and non-autologous tumor growth on the omentum (162.22)

Abstract

Abstract Tumor cell metastasis to the peritoneal cavity (PC) is a serious concern for many cancers, including ovarian and colon tumors. Upon introduction to the PC, tumor cells bind to the omentum, a tissue comprised of adipose embedded with organized immune aggregates (IA) thought to have regulatory function. Interestingly, it is to these IA that tumor cells initially bind and thrive. This presents a unique situation in which tumor cells are in close proximity to potential effector cells. However, without a stimulus to override their regulatory function, IA fail to control tumor growth. Thus, we attempted to stimulate a response by immunizing mice with a lethally irradiated colon adenocarcinoma cell line: Colon38 (C38). Our data demonstrates that i.p. immunization with C38 is capable of preventing growth of C38 upon live tumor challenge. Although T cells are necessary to generate this response, when CD8 or CD4 T cells were depleted during the effector phase, tumor growth was still controlled; suggesting T cells are not the effector cells. Interestingly, in mice immunized with C38 and challenged with another tumor cell line, E0771, tumor growth was also prevented. This non-specific response is unique to the PC, as mice that were immunized with C38 and challenged with E0771 by an alternate (i.m.) route developed tumors. Together, these data suggest that i.p. immunization results in T cell induction of an innate/non-specific anti-tumor response.