Immunocompetence of tissue infiltrating lymphocytes in bladder tumors

Tissue infiltrating lymphocytes (TIL) in bladder tumors have been assumed to be an expression of local host resistance against the tumor. We investigated the functional activity of TIL compared to peripheral blood lymphocytes (PBL). Isolation of TIL was performed using the enzyme cocktail treatment with Ficoll-Hypaque discontinuous gradient centrifugation. Analysis of lymphocyte subsets by flow cytometry demonstrated Leu 4, 43.6% (T cells); Leu 10, 10.5% (B cells) and Leu 7, 13.1% (natural killer (NK) cells) in TIL. The cytotoxic activity of TIL and PBL was tested in a four hour 51Cr-release assay. Myeloid K562 cells (NK sensitive), HT 1197 (bladder tumor) and fresh bladder tumors were used as target cells. The spontaneous NK cell activity of PBL was 23.7%, whereas that of TIL was only 3.5%. However, in vitro culture with IL2 induced a significant augmentation of NK activity in TIL as well as in PBL. On the other hand, the spontaneous lymphokine activated killer cell (LAK) activity of PBL and TIL was very low. IL2-cultured PBL and TIL exhibited the highest levels of lysis against fresh bladder tumors. Unlike PBL, IL2-induced cytotoxicity of TIL against autologous bladder tumors was higher than that against allogenic bladder tumors. Immunomodulators OK432 and Il2 were injected intratumorally during endoscopy. Analysis of the lymphocyte subsets in TIL showed an increase of T and NK cells following immunomodulator injection. Endoscopic injection of immunomodulators into bladder tumors augmented NK cell functional activity in TIL as well as PBL. These findings suggest that local immunosurveillance is directed against bladder tumors. Further studies are required to understand more fully the local and systemic host immune responses in cancer.