Immunological Properties of TtT/M‐87 Cell Line Established from Murine Pituitary Tumor‐Associated Macrophages

Abstract

TtT/M‐87 cell is a macrophage cell line established from thyrotropic pituitary tumor tissues in mouse. In this paper, we report the immunological properties of M‐87 cells as a model of tumor‐associated macrophage. Contrasting with resident peritoneal macrophages, M‐87 cells constitutively secreted small but significant amounts of TNF‐α and IL‐1α, which were detectable in both biological assays (cytotoxic activity for L929 and co‐mitogenic activity for Con A‐induced T cell proliferation, respectively) and ELISA, and produced larger amounts of these cytokines upon stimulation with LPS. They expressed MHC class II molecules on their cell surface without stimulation by IFN‐γ. The accessory or antigen‐presenting cell activity in antibody‐producing response of spleen lymphocytes to sheep red blood cells was shown to be much higher in M‐87 cells than normal peritoneal macrophages. In addition, when normal spleen lymphocytes were cultured with allogeneic tumor cells, such as EL‐4 and S‐180, in the presence of M‐87 cells, lymphocytes reactive to stimulator cells were activated to manifest inhibitory effect on the tumor cell growth and also to manifest specific cytotoxic effect on the allogeneic tumor cells. These results show that M‐87 cells derived from tumor‐associated tissue are activated macrophages and that they are inhibitory to tumor cell growth and augmentative in the induction of T‐cell‐mediated immune responses.

Tumor-Associated Macrophages: New Horizons for Pituitary Adenoma Researches

“…In 1993, TtT/M-87 was separated from PAs. TtT/M-87 is a macrophage cell line derived from thyroid stimulating hormone (TSH)-secreting adenomas that express TNF-α, IL-1α, and MHC-II; these factors can assist spleen-derived lymphocytes in inhibiting the growth of tumor cell lines in vitro ( 39 ). Due to the lack of relevant research, further in vivo and in vitro studies are needed to verify the role of M1-TAMs in PAs.…”