Increase in the capability of interleukin 2 gene-transduced renal cell carcinoma cells to induce cytotoxic lymphocytes

The immunogenicity of human cancer cells transfected with interleukin 2 (IL-2) gene, a potent vaccine candidate, has not yet been fully investigated. Human renal cell carcinoma (RCC) cells transduced with human IL-2 gene (RCC-IL-2) were investigated in vitro for the capability to induce lymphokine-activated killer (LAK) or cytotoxic T lymphocyte (CTL) activity in peripheral blood mononuclear cells (PBMC) or tumor-infiltrating lymphocyte (TIL). The RCC-IL-2 cells stimulated PBMC to demonstrate LAK activity, and also stimulated autologous TILs to proliferate and exhibit cytotoxicity relatively restricted to autologous tumor cells. In contrast, both parental RCC and RCC transduced with neomycin gene alone failed to induce these activities. These results indicate that RCC-IL-2 cells are more potent than the other RCC cells with regard to inducing cytotoxic lymphocytes against autologous tumor cells.

Increase in the ability of human cancer cells to induce cytotoxic T lymphocytes by ultraviolet irradiation

The roles of ultraviolet-B (UV) radiation in the immunogenicity of human cancer cells have not been fully studied. We have investigated the effects of UV radiation on metastatic melanoma and renal cell carcinoma cells with regard to MHC antigen expression and the ability to induce cytotoxic T lymphocyte (CTL) activity in peripheral blood mononuclear cells (PBMC) or tumor-infiltrating lymphocytes (TIL) against untreated autologous tumor cells. UV radiation respectively decreased or increased MHC class I expression of freshly isolated tumor cells or cultured tumor cells, and also decreased MHC class I expression of starved cultured tumor cells. It increased the ability of both freshly isolated and cultured tumor cells to induce CTL activity from PBMC against untreated autologous tumor cells. UV-irradiated subclones that were more susceptible to CTL lysis were more potent for CTL induction from TIL than either an untreated parental clone or a UV-irradiated subclone that was resistant to CTL lysis. In summary, UV radiation increased the ability of tumor cells to induce CTL activity without a corresponding effect on MHC antigen expression.

Cytokine production and immune cell activation in melanoma patients treated with liposomal muramyl tripeptide (CGP 19835A lipid)

We conducted a pilot study using liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE) preoperatively in patients with stage III or IV resectable melanoma who were at high risk for recurrence. Patients received L-MTP-PE for 1 month before surgery and then 5 months postoperatively. Several immune parameters were monitored during preoperative therapy to search for correlations with clinical (tumor) response. The 18 patients were classified into three groups according to their responses and disease-free intervals: no evidence of disease (NED) at week 24 of therapy, relapse during therapy and progressive disease on therapy noted at the time of surgery. Six of nine patients in the NED group demonstrated increased monocyte tumoricidal activity (MTA) during week 1 of therapy. MTA increased in three of the six patients in the relapse group. MTA did not increase in the three patients who had progressive disease on therapy. Plasma neopterin levels were elevated by 72 h following the first L-MTP-PE dose in all 18 patients. Circulating levels of tumor necrosis factor were elevated in 15 of 16 patients tested, and IL-6 levels were elevated in all 18 patients. Melanoma cells from all three patients with progressive disease at the time of surgery proliferated well in vitro, whereas tumor cells from 10 of the 15 patients in the other two groups did not proliferate. There were no discernible differences among the three groups in the magnitude of IL-2-induced proliferation of tumor infiltrating lymphocytes. However, IL-2-activated TILs from the NED group exhibited cytotoxicity against autologous tumor cells in vitro. In summary, whereas L-MTP-PE stimulated several immunologic responses in all patients, the only two parameters that correlated with clinical status were MTA and the tumor proliferation assay. These two biologic assays could serve to distinguish potential responders from nonresponders early in the course of treatment.

Distribution of autologous tumor-specific cytotoxic T lymphocytes in human metastatic melanoma

The study of specific immunity in human cancers has been hampered by the elusive distribution and heterogeneity of effector cells. In this study, we have investigated the distribution of autologous melanoma-specific cytotoxic T lymphocytes (CTLs) in 18 different distant metastases from melanomas (9 non-visceral and 9 visceral metastases). Uncultured cells from tumors were provided directly for the establishment of T-cell clones using limiting dilution analysis to avoid any possible effects of in vitro sensitization of T cells to coexisting tumor cells. Autologous tumor specific CTL clones were detected in 6 of 18 tumors (33%, 4 non-visceral and 2 visceral metastases). The majority of CTL clones (35 of 46 and 17 of 19) in 2 patients with HLA class-I A2 haplotype failed to lyse either A2+ or A2- allogeneic melanoma cells, although anti-class-I (monomorphic) MAb inhibited their cytotoxicity. The remaining 11 of 46 and 2 of 19 CTL clones showed A2-restricted cytotoxicity. Autologous tumor-specific cytotoxicity was also detected after polyclonal culture of these tumor-infiltrating lymphocytes (TILs) in 8 of 16 tumors (50%, 5 non-visceral and 3 visceral metastases). These results suggest that tumor-specific T cells exist at tumor sites in at least one-third of distant metastases of melanomas and could be induced by the addition of IL-2 in at least half of the tumors. Tumor-specific T cells were detectable more often in non-visceral than in visceral metastases.

Human renal-cell carcinoma cells are able to activate natural killer cells

We previously reported that natural killer (NK) cells that had infiltrated renal-cell carcinoma (RCC) proliferated vigorously in culture with interleukin-2 (IL-2) and lysed autologous tumor cells. In this study, we investigate the susceptibility of RCC cells to NK-cell lysis and their ability to stimulate proliferation and increase phenotypic expression and function of NK cells. Cells from primary culture of RCC (p-RCC cells) were significantly more susceptible to the lysis mediated by human NK3.3 clones than were cells from primary culture of metastatic melanomas. Both RCC-cell clones and cells from primary culture of non-tumorous kidneys were also susceptible to lysis by NK3.3 clones and IL-2-activated peripheral blood lymphocytes (PBLs). Incubation of NK3.3 clones with p-RCC cells in the absence of IL-2 induced proliferation of NK3.3 clones, whereas incubation with cells from primary culture of metastatic melanomas, K562 cells, or any others tested did not. The p-RCC cells from earlier passages were more potent inducers of NK-cell proliferation than were those from older passages. Cell-free culture supernatants of p-RCC cells with or without NK3.3 clones failed to induce NK-cell proliferation. Incubation of CD16+ NK cells purified from PBLs with p-RCC cells induced higher proliferation of the NK cells only in the presence of IL-2, whereas incubation with cells from primary culture of metastatic melanomas did not. Incubation of NK3.3 clones with p-RCC cells resulted in an increase in CD16, CD25 (IL-2 receptor-alpha), and HLA-DR antigen expression and cytotoxicity in NK3.3 clones. In summary, these results suggest that RCC cells are able to activate NK cells, potentially through cell-to-cell interaction.

Study of tumor-infiltrating lymphocytes for adoptive therapy of renal cell carcinoma (RCC) and metastatic melanoma: sequential proliferation of cytotoxic natural killer and noncytotoxic T cells in RCC

We investigated the immunological properties of interleukin-2 (IL-2)-activated tumor-infiltrating lymphocytes (TIL), which were used for adoptive therapy of renal cell carcinoma (RCC) (seven patients) by focusing on natural killer (NK) cells, and metastatic melanoma (six patients) by focusing on cytotoxic T lymphocytes. TIL from five of seven cases proliferated well in culture with AIM-V serum-free medium and 1000 U/ml rIL-2 in 3-L gas permeable bags, whereas TIL from two RCCs exhibited delayed proliferation. Proliferation of CD3-CD56+ NK cells with major histocompatibility complex-nonrestricted cytotoxicity in RCC-TIL (n = 6, mean = 651-fold, ranging from 39- to 3450-fold) for the first 2-4 weeks was 63 times higher than that of noncytotoxic CD3+ T cells (n = 6, 10.3-fold ranging from 0.8 to 35-fold). Thereafter, CD3+ T cells predominantly proliferated, and proliferation of CD3+ T cells (n = 5, 743-fold) for 5-6 weeks were 24 times higher than that of CD3-CD56+ NK cells (n = 5, 31-fold). Significant numbers of RCC-TIL became adherent to the surfaces of the bags several weeks after initiation of culture. These adherent TIL consisted of more CD3-CD56+ NK cells and exhibited higher cytotoxicity than did nonadherent TIL. Adherent RCC-TIL produced interferon (IFN)-gamma, while nonadherent TIL did not. These results suggest that initially cytotoxic CD3-CD56+ NK cells and, later, noncytotoxic CD3+ T cells proliferated in culture of RCC-TIL for adoptive therapy. These noncytotoxic TIL were primarily transferred to RCC patients, who also received cyclophosphamide, IL-2, and IFN-alpha. In contrast to RCC-TIL, IL-2-activated melanoma TIL consisting of all CD3+ T cells displayed modest levels of cytotoxicity, primarily restricted to autologous melanoma cells in all cases tested. The cytotoxic melanoma TIL were adoptively transferred to melanoma patients. Three of seven RCC patients responded to the adoptive therapy.

Carcinoembryonic antigen as a selective enhancer of colorectal cancer metastasis

Although the serum level of carcinoembryonic antigen (CEA) is directly associated with a poor prognosis in human colorectal carcinoma (CRC), its function is obscure. As a member of the immunoglobulin supergene family, CEA may be involved with intercellular recognition and binding and facilitate attachment of CRC to sites of metastasis. In an experimental metastasis model of CRC in athymic nude mice, a systemic injection of CEA enhanced experimental liver metastasis and implantation in liver by a weakly metastatic CRC. This CRC also selectively bound to CEA that was attached to plastic. Thus, CEA may function as an attachment factor for CRC.