Transfer of the interleukin-2 gene into human cancer cells induces specific antitumor recognition and restores the expression of CD3/T-cell receptor associated signal transduction molecules.

Normal peripheral blood mononuclear cells (PBMC) were co-cultured with a human lung cancer cell line (LC89) transduced with the interleukin-2 (IL-2), IL-7, granulocyte-macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor-alpha (TNF-alpha) genes to evaluate the capacity of the engineered cells to: allow survival of CD3+ and CD56+ cells, generate cytotoxic effectors with HLA class I restricted and unrestricted antitumor activity, and interfere in the molecular organization of the CD3/T-cell receptor associated signal transduction machinery. When PBMC were cultured up to 3 weeks with IL-2 releasing LC89 cells (LC89/IL-2), the number of viable CD3+ and CD56+ lymphocytes was much greater than in cultures with parental cells or with LC89 cells transduced with the other cytokine genes. After 1 week of coculture, a variable degree of restricted and unrestricted killing directed against different targets was observed. When the cultures were prolonged up to 3 weeks, LC89/IL-2 cells induced a marked increase in specific cytotoxic activity, which was coupled to a further enhancement of unrestricted lytic function. In the presence of LC89/IL-7 cells the degree of specific lysis remained unchanged, whereas unrestricted effectors were markedly decreased. No cytotoxic activity could be induced by LC89/GM-CSF and LC89/TNF-alpha cells in the few lymphocytes surviving after 3 weeks of culture. Coculture of parental LC89 cells with PBMC was consistently associated with a downmodulation in the expression of the CD3 zeta chain, as well as of the tyrosine kinases p56ick and ZAP-70. On the contrary, LC89/IL-2 cells, and not LC89 cells transduced with the IL-7, GM-CSF, or TNF-alpha gene, were capable of reverting the immunosuppressive effect exerted by the tumor cells. This protective effect could be maintained in cultures prolonged up to 4 weeks. When the same cultures were set up in Transwell, ie, with a membrane separation between cancer cells and PBMC, the expression of the CD3 zeta chain and of the p56ick and ZAP-70 tyrosine kinases remained unchanged under all culture conditions, indicating that the downmodulation of T-cell signal transduction molecules requires a direct cell to cell contact. These results show that transfer of the IL-2 gene into the DNA of human cancer cells promotes both restricted and unrestricted antitumor activity, and is capable of restoring and maintaining the expression of molecules involved in the process of T-cell mediated tumor cell recognition, thus underlining the potential role of the IL-2 gene in the design of vaccination protocols with cytokine gene transduced cancer cells.

Clinical and immunological studies in advanced cancer patients sequentially treated with anti CD3 monoclonal antibody (OKT3) and interleukin-2.

CD3 engagement has been used as a surrogate for antigen-specific stimulation to trigger T cell effector functions. Exogenous IL-2 has been used to prolong and amplify CD3-induced T cell activation. Previous studies have been shown that CD3 reactivity is increased in cancer patients with preactivated (> 10% HLA-DR+) T cells in the peripheral blood. In this study, we report 9 courses of a single infusion of anti-CD3 mAb (OKT3) followed by continuous infusion of intermediate dose IL-2 in 4 cancer patients [2 multiple myeloma (MM), 1 B-cell lymphoma (NHL), 1 metastatic melanoma (ME)] with advanced disease and > 10% HLA-DR+ T cells in the peripheral blood. An increase of lymphocytes, equally distributed between CD4+ and CD8+ subsets, was observed during treatment. Activation was phenotypically documented by the emergence of CD25+ cells in the peripheral blood. Unexpectedly, functional studies [including proliferation to mitogens (PHA, OKT3) and cytotoxicity assays (NK and LAK activities)] did not parallel phenotypic data and a slight decrease of all functions was observed after OKT3 and IL-2 treatment. OKT3 and IL-2 infusions were well tolerated and no limiting toxicity was observed. The treatment did not revert tumor progression in the 2 patients with progressive disease (NHL, ME) and had only minimal effects in the 2 MM patients with stable disease. These data indicate that the sequential administration of OKT3 and IL-2 had no anti-tumor activity in this small series of patients with advanced cancer who were selected for treatment because of an increased number of HLA-DR+ T cells in the peripheral blood. A discrepancy was observed between the emergence of CD25+ T cells and the clinical outcome.

CD3-induced T-cell activation in the bone marrow of myeloma patients: major role of CD4+ cells.

A large expansion of activated T cells (CD3+CD25+) with the potential to act as anti-tumour effector cells is inducible in multiple myeloma (MM) patients by culturing bone marrow mononuclear cells (BMMCs) with the anti-CD3 monoclonal antibody (mAb) OKT3. The aim of this study was to provide a greater characterization of CD3-activated T cells. On day 6, most T cells coexpressed the CD11a, CD18, CD54, CD45R0 antigens and consisted of activated (CD25+) CD4+ and CD8+ cells in nearly equal proportions. Kinetics studies showed that CD4+CD25+ cells proliferated more rapidly and peaked earlier than CD8+CD25+ cells. When experiments were performed with purified subpopulations by removing CD4+ cells (resulting in CD8+ BMMCs) or by removing CD8+ cells (resulting in CD4+ BMMCs). T-cell activation and autologous plasma cell decrease were observed in CD4+ BMMCs only. Transwell cultures showed that CD4 help was necessary to make CD8+ BMMCs susceptible to CD3 stimulation. Relevant amounts of IL-2 were found in the supernatants of CD4+ BMMCs cultures, whereas no secretion of IL-4 was detected, indicating a Th1-like profile of CD3-activated CD4+ cells. These data indicate that CD4+ cells proliferate earlier and provide optimal help to induce the subsequent expansion of CD8+ cells after CD3 stimulation of MM BMMCs. Adequate stimulation of CD4+ cells is therefore essential in any strategy aiming to recover T-cell-mediated immunity in MM.

Dysregulated Fas and Bcl-2 expression leading to enhanced apoptosis in T cells of multiple myeloma patients.

We have previously reported the presence of activated (HLA-DR+) T cells in multiple myeloma (MM) patients. These cells produce high amounts of interleukin (IL)-2 and interferon (IFN)-gamma and generate a potent antiplasma cell activity after appropriate in vitro stimulation, but they are unable in vivo to hold in check the disease. Activated T cells are highly susceptible to apoptosis, a form of programmed cell death involved in the modulation of immune responses and regulated by molecules such as Fas (CD95) and bcl-2. The aim of this study was to determine the expression of Fas and bcl-2 antigens and the susceptibility to apoptosis in T cells of MM patients. Fas+ cells were significantly higher, whereas bcl-2+ cells were significantly lower in MM patients than in the controls. MM patients with the highest number of HLA-DR+ T cells showed the highest Fas and the lowest bcl-2 expression. Two-color cytofluorometric analysis confirmed in individual cells that HLA-DR+ T cells coexpressed Fas and lacked bcl-2. Susceptibility to apoptosis was then investigated to evaluate the consequence of dysregulated Fas and bcl-2 expression. The percentage of apoptotic cells after incubation in medium alone (spontaneous apoptosis) or in the presence of methylprednisolone (MP) or anti-Fas monoclonal antibody (triggered apoptosis) was significantly higher in MM and mainly restricted to HLA-DR+ T cells. Spontaneous apoptotosis was reverted by exogenous IL-2. In conclusion, MM T cells have a dysregulated expression of Fas and bcl-2 antigens that is associated with an enhanced susceptibility to apoptosis. These data may unravel a novel mechanism by which activated MM T cells are weakened in their ability to exert an effective antitumor activity in vivo.

Generation of anti-tumour activity by OKT3-stimulation in multiple myeloma: in vitro inhibition of autologous haemopoiesis.

T cells in multiple myeloma (MM) patients are highly susceptible to activation with the anti-CD3 monoclonal antibody (mAb) OKT3. When short-term OKT3 stimulation is carried out on bone marrow mononuclear cells (BMMC), large numbers of CD3+ CD25+ HLA-DR+ cells are rapidly generated and autologous malignant plasma cells are killed. OKT3 may thus be exploited in autologous bone marrow transplantation (ABMT) to purge residual plasma cells and simultaneously activate T cells to induce graft-versus-leukemia-like (GVL-like) activity upon reinfusion. However, the possible impact of ex-vivo short-term OKT3 stimulation on haematological recovery is unknown. The aim of this work was to investigate the effect of OKT3 stimulation in vitro on autologous haemopoietic progenitor cells (HPC) of MM patients. Colony formation by granulocyte-macrophage progenitor cells (granulocyte-macrophage colony-forming units, CFU-GM) was highly suppressed, although supernatants of OKT3-activated T cells contained up to 2,500 pg/ml of granulocyte-macrophage colony-stimulating factor (GM-CSF). T cell depletion completely prevented this suppression. Neutralizing antibodies against TNF-alpha, TNF-beta and IFN-gamma (which are also produced by OKT3-activated MM T cells) did not prevent it, and Transwell cultures showed that cell-to-cell contact was the main mechanism involved. OKT3-activated T cells also suppressed erythroid burst-forming units (BFU-E) and CFU-GM generation from HPC responsible for long-term maintenance of in vitro myelopoiesis. When tested on normal allogeneic BM, MM supernatants of OKT3-stimulated BMMC partially suppressed the generation of day 7 CFU-GM, but had no effect on day 14 CFU-GM. These data indicate that short-term stimulation of BMMC with OKT3 can be used to generate anti-tumour effector T cells for autologous adoptive immunotherapy. It is not a feasable approach for ex-vivo purging and activation procedures in ABMT because of its potent inhibition of autologous haemopoiesis.

Rapid generation of antiplasma cell activity in the bone marrow of myeloma patients by CD3-activated T cells.

We have recently shown that peripheral blood T cells of multiple myeloma (MM) patients are very susceptible to stimulation of the T-cell receptor/CD3 complex with anti-CD3 monoclonal antibodies (MoAbs). CD3 stimulation is currently under clinical investigation as a nonspecific approach to boost antitumor effector mechanisms. The aim of this study was to determine whether the hyperreactivity of MM T cells to CD3 stimulation could be exploited to generate antitumor activity. Bone marrow mononuclear cells (BMMCs) from 65 MM patients were stimulated with the anti-CD3 MoAb OKT3 and the effect of this stimulation on autologous T cells and plasma cells was evaluated. The number of CD3+ CD25+ cells on day 6 was significantly higher in MM than the controls (30 normal individuals) (P = .001). Kinetic studies showed that 3H-thymidine incorporation peaked on day 3 and that the T-cell expansion peaked on days 5 and 6. In MM, T-cell activation markedly affected the survival of autologous plasma cells; their number in OKT3-treated cultures was significantly lower than in unstimulated cultures (P < .0001). T-cell activation and plasma cell decrease were not observed when T cells were removed from BMMC preparations. MM produced significantly higher levels of interferon-gamma (P = .005) and tumor necrosis factor-beta (P = .001), but lower levels of tumor necrosis factor-alpha (P < .001) than normal individuals. Interferon-gamma only was partially involved in CD3-induced plasma cell killing. Transwell cultures showed that the main mechanism by which CD3+ CD25+ cells affected plasma cells was direct cell-to-cell contact rather than cytokines. In conclusion, T cells in MM BMMCs possess distinct features in terms of susceptibility to CD3 stimulation and cytokine production compared with normal bone marrow T cells that can be exploited to generate antiplasma cell activity.