Functional Analysis of Mononuclear Cells Infiltrating into Tumors: Establishment of a New System to Obtain Functionally Active Tumor‐infiltrating Cells

We have demonstrated that tumor‐infiltrating T cells play a crucial role in tumor growth. In order to investigate the precise function of tumor‐infiltrating cells, we avoided the use of any enzyme for separation of tumor‐infiltrating cells from the solid tumor mass and established a new system in which we could easily obtain functionally active tumor‐infiltrating cells in large amounts from the peritoneal cavity of T‐9 gliosarcoma‐sensitized rats. In this system, viable T‐9 cells were intraperitoneally administered and peritoneal exudate cells were recovered. Importantly, cells obtained from the intraperitoneal cavity are phenotypically and functionally indistinguishable from those obtained from subcutaneous tumor masses. Furthermore, injection of purified lymphocyte migration factor‐b resulted in the accumulation of CD8 (+) cytotoxic T cells in the peritoneal cavity. Therefore, this system also provides a means by which the in vivo function of chemotactic factor can be tested.