Cytotoxic T lymphocytes (Tc) play a central role in cellular immunity against cancers. The cytotoxic potential of freshly isolated tumor-infiltrating lymphocytes (TILs) is usually not expressed. This suggests the possible existence of as yet unspecified and perhaps complex immunosuppressive factors or cytokines that affect the anti-tumor capacity of these TILs in the tumor milieu. In the present study, we demonstrated for the first time that TILs derived from human cervical cancer tissue consist mainly of Th2/Tc2 phenotypes. In vitro kinetic assays further revealed that cancer cells could direct the tumor-encountered T cells toward the Th2/Tc2 polarity. Cancer cells promote the production of IL-4 and down-regulate the production of IFN-γ in cancer-encountered T cells. The regulatory effects of cervical cancer cells are mediated mainly by IL-10, and TGF-β plays only a synergistic role. The cancer-derived effects can be reversed by neutralizing anti-IL-10 and anti-TGF-β Abs. IL-10 and TGF-β are present in cancer tissue and weakly expressed in precancerous tissue, but not in normal cervical epithelial cells. Our study strongly suggests important regulatory roles of IL-10 and TGF-β in cancer-mediated immunosuppression.

Inhibitory signals that govern the cytolytic functions of CD8⁺ T lymphocytes have been linked to the expression of natural killer cell receptors (NKRs) on CTLs. There is limited knowledge about the induction of inhibitory NKR (iNKR) expression in vivo. Up-regulation of iNKRs has been linked to the modulation of the virus- and/or tumor-specific immune responses in animal models. In the present study, we directly examined the expression of various NKRs on tumor-infiltrating lymphocytes (TILs) derived from human cervical cancer. We found that in human cervical cancer, the percentage expression of immunoglobulin-like NKR⁺CD8⁺ T lymphocytes were similar in gated CD8⁺-autologous TILs and peripheral blood mononuclear cells. On the contrary, cervical cancer–infiltrating CD8⁺ T lymphocytes expressed up-regulated C-type lectin NKRs CD94/NKG2A compared with either peripheral blood CD8⁺ T cells or normal cervix-infiltrating CD8⁺ T lymphocytes. Dual NKR coexpression analyses showed that CD94 and NKG2A were mainly expressed on CD56⁻CD161⁻CD8⁺ TILs within the cancer milieu. Immunohistochemical study showed that cervical cancer cells expressed abundant interleukin 15 (IL-15) and transforming growth factor-β (TGF-β). In kinetic coculture assay, cervical cancer cells can promote the expression of CD94/NKG2A on CD8⁺ T lymphocytes. The cancer-derived effects can be reversed by addition of rIL-15Rα/Fc and anti–TGF-β antibody. Functional analyses illustrated that intracellular perforin expression of CD8⁺ T cells was minimal upon up-regulation of CD94/NKG2A. Kinetic cytotoxicity assays showed that up-regulated expressions of CD94/NKG2A restrain CD8⁺ T lymphocyte cytotoxicity. Our study strongly indicated that cervical cancer cells could promote the expression of iNKRs via an IL-15– and possibly TGF-β–mediated mechanism and abrogate the antitumor cytotoxicity of TILs.

During carcinoma formation, cancer cells release various cytokines and growth factors into their surroundings and recruit and reprogram many other types of cells in order to establish a tumor microenvironment. Consequently, the tumor tissues almost always contain a large number of endothelial cells, fibroblasts, and infiltrating inflammatory cells that in turn produce a variety of cytokines. The cytokines produced by these cells have been posited as key factors in modulating immune response either against or in favor of tumorigenesis in the microenvironment. The interactions that take place between immune and cancer cells are complex, involving multiple cascades of cytokines, chemokines, and/or growth factors. In this review, we address the essential pro- and anti-tumorigenic roles of cytokines in the tumor microenvironment. As the interaction of cytokines, growth factors, and cancer cells forms a comprehensive network at the tumor site that is then responsible for the overall progression or rejection of the tumor, the current review links the microenvironment-derived cytokines and growth factors to a number of different kinds of human carcinogenesis models. Multifunctional cytokines, extracellular matrix mediators, and regulatory cytokines in the cancer environment are all shown to be key factors in the different cancer immune-editing systems. The characterization of cytokine networks in various types of cancer cells may yield important information for understanding the immune-related mechanisms of cancer development, and this knowledge may have subsequent application in cancer immunotherapy.

BACKGROUND To investigate the clinical significance of tumor‐infiltrating lymphocytes (TILs) within the tumor milieu of human cervical carcinoma, the authors quantitatively measured and compared the subpopulations of lymphocytes infiltrating the neoplastic cervix. METHODS A total of 30 patients with Stage Ia–IIa cervical carcinoma were enrolled. TILs were isolated from tissue specimens by means of a mechanical dispersal technique, and the immunocyte subsets were quantified with dual‐color flow cytometry. Bulky tumor was defined as tumor size >4 cm in greatest dimension according to the 1995 staging of the International Federation of Gynecology and Obstetrics. RESULTS The CD4/CD8 ratios of TILs were reversed in both cervical squamous cell carcinoma (n = 20) and cervical adenocarcinoma (n = 10). The proportion of CD4⁺ T cells was significantly lower in tumors from patients with lymph node metastasis (n = 8) than in those from patients without lymph node metastasis (n = 22) (24.5 vs. 32.7, P = 0.001), as was the reversed CD4/CD8 ratio (0.50 vs. 0.81, P = 0.001). The proportion of CD4⁺ T cells was much lower in bulky tumors (n = 5) than in nonbulky tumors (n = 25) (21.4 vs. 32.5, P < 0.001), reflecting in a more strongly reversed CD4/CD8 ratio (0.41 vs. 0.81, P = 0.001). CONCLUSIONS Decreased proportions of tumor‐infiltrating CD4+ T cells with reversed CD4/CD8 ratios are highly correlated with rapid tumor growth and lymph node metastasis in cervical carcinoma. The regional immune escape is of prognostic importance with regard to cancer progression. Cancer 1999;86:1537–43. © 1999 American Cancer Society.