The in vivo anti-tumor effect of human recombinant interleukin-6

A phase-I clinical trial of active immunotherapy for acute leukemia using inactivated autologous leukemia cells mixed with IL-2, GM-CSF, and IL-6

We evaluated the efficacy and toxicity of vaccination in 29 patients with relapsed or refractory acute leukemia using inactivated autologous leukemia cells combined with interleukin-2 (IL-2), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-6. MHC-I, MHC-II, and B7-1 expression status on the surface of leukemia cells and the cytokine profile of IFN-gamma and IL-10 in serum before and after vaccination was detected.

RESULTS

Five achieved a complete remission (CR) and six a partial remission (PR) in this vaccination procedure. Adverse effects were erythema, swelling erosion, and even ulcers at vaccination sites and low grade fever during the first three days of vaccination. No other significant side effects were observed. The expression of MHC-I and MHC-II on leukemia cells was 100% and 90% positive, respectively. B7-1 was exclusively expressed on some cases of M4 and M5. The efficacy of the vaccine was statistically associated with the expression status of B7-1 on leukemia cells (P < 0.01). The serum level of IL-10 reduced significantly in the five patients who achieved complete remission (CR) after vaccination as compared with when they were originally diagnosed (P < 0.01).

CONCLUSION

We presented here a promising immunotherapy in the treatment of acute leukemia, especially for F.A.B. M5.

Subpopulations of mononuclear leukocytes associated with inhibition of Ehrlich ascites tumor growth by treatment with Bothrops jararaca venom

Snake venoms have been used as antineoplastic substances in several experimental models. We demonstrated in previous studies that Bothrops jararaca venom (BjV) induces inhibition of Ehrlich ascites tumor (EAT) growth accompanied by an increase of mononuclear (MN) leukocytes in all groups inoculated with EAT and/or venom. The objective of the present study was to characterize the subpopulations of MN leukocytes involved in the inhibition of EAT growth by treatment with BjV. Swiss mice were inoculated with 1.0x10(3) EAT cells by the intraperitoneal route and treated with 0.4 mg/kg of BjV by the same route (Group TV). Treatment was started 24 h after tumor cell inoculation and consisted of five intraperitoneal injections performed at 72 h intervals. After 2, 8 and 14 days, groups of animals were sacrificed and the number of B, TCD4 and TCD8 lymphocytes, macrophages and natural killer cells present in the peritoneal cavity was determined by flow cytometry. The control group consisted of animals inoculated with EAT and treated with 0.1 ml of saline under the same conditions as the experimental group (Group T). Two additional control groups consisted of animals not inoculated with EAT and treated with saline or venom. Data were analyzed statistically by the Kruskal-Wallis non-parametric test for independent samples. On the 2nd and 8th day we observed a difference between groups T and TV (group T > group TV) for all cell types, except natural killer cells, that only differed on the 2nd day. However, on the 14th day there was no difference in MN cells among groups. These data suggest that the inhibition of EAT is related to the toxic action of BjV on tumor cells and/or to the proteolytic effect of the venom on the mediators produced by the cells for growth modulation.

Antitumor effect of Bothrops jararaca venom

Many experimental studies have been carried out using snake venoms for the treatment of animal tumors, with controversial results. While some authors have reported an antitumor effect of treatment with specific snake venom fractions, others have reported no effects after this treatment. The aim of this study was to evaluate the effect of Bothrops jararaca venom (BjV) on Ehrlich ascites tumor (EAT) cells in vivo and in vitro. In the in vivo study, Swiss mice were inoculated with EAT cells by the intraperitoneal (i.p.) route and treated with BjV venom (0.4 mg/kg, i.p.), on the 1st, 4th, 7th, 10th, and 13th days. Mice were evaluated for total and differential cells number on the 2nd, 5th, 8th, 11th and 14th days. The survival time was also evaluated after 60 days of tumor growth. In the in vitro study, EAT and normal peritoneal cells were cultivated in the presence of different BjV concentrations (2.5, 5.0, 10.0, 20.0, 40.0, and 80 microg) and viability was verified after 3, 6, 12 and 24 h of cultivation. Results were analyzed statistically by the Kruskal-Wallis and Tukey tests at the 5% level of significance. It was observed that in vivo treatment with BjV induced tumor growth inhibition, increased animal survival time, decreased mortality, increased the influx of polymorphonuclear leukocytes on the early stages of tumor growth, and did not affect the mononuclear cells number. In vitro treatment with BjV produced a dose-dependent toxic effect on EAT and peritoneal cells, with higher effects against peritoneal cells. Taken together, our results demonstrate that BjV has an important antitumor effect. This is the first report showing this in vivo effect for this venom.

Serum proinflammatory cytokine response in patients with advanced liver tumors following selective internal radiation therapy (SIRT) with (90)Yttrium microspheres

PURPOSE

To determine the changes in serum levels of proinflammatory cytokines within 48 h after selective internal radiation treatment (SIRT) in patients with advanced liver cancers.

METHODS AND MATERIALS

Twenty-eight patients with advanced liver cancers who underwent SIRT were recruited into the study. Serum levels of interleukin (IL)-1beta, IL-6, IL-8, IL-10, IL-12, tumor necrosis factor-alpha, and interferon-gamma were determined prior to and 3, 6, 12, 24, and 48 h after SIRT. Their changes were correlated to adverse reactions following treatment as assessed by constitutional symptom scores, and routine blood and liver function tests at 24 and 48 h post-SIRT and falls in serum carcinoembryonic antigen (CEA) level 1 month post-SIRT.

RESULTS

Serum IL-6 levels were significantly increased at 24 (p < or = 0.05) and 48 h (p < or = 0.01) post-SIRT. In contrast, there was no significant change in the serum levels of other cytokines studied. The increase in serum IL-6 at 24 h post-SIRT was significantly correlated with the changes in serum alanine transferase (p < or = 0.05) and C-reactive protein (p < or = 0.001) levels and total leukocyte counts (p < or = 0.001) at both 24 and 48 h post-SIRT. Changes in serum IL-6 level were also significantly correlated to the rise of serum aspartate transaminase levels at 48 h post-SIRT (p < or = 0.001), but not with the scores of constitutional symptoms or the changes of serum CEA at 1 month post-SIRT.

CONCLUSION

Absence of significant changes in most of proinflammatory cytokines studied confirmed that SIRT is a reasonably safe and well-tolerated treatment with minimal side-effect from the point of view of cytokine-related inflammation. The correlation of serum IL-6 changes with several liver enzymes and C-reactive protein but not with clinical symptom scores or serum CEA levels suggests that the rise in IL-6 levels in the first 48 h following SIRT most likely reflect normal liver cell damage rather than tumor cell damage.

Suppression of the tumorigenic growth of Burkitt's lymphoma cells in immunodeficient mice by cytokine gene transfer using EBV-derived episomal expression vectors

Epstein-Barr virus (EBV)-based expression vectors were tested for cytokine gene transfer-mediated induction of an immune response against human lymphoma cells. These vectors express the EBV latent gene EBNA 1 and carry the EBV latent origin of replication (ori P) for episomal replication in transfected cells. In addition, 3 human immunoglobulin light chain enhancer elements augment expression in B-cells. The suitability of these vectors for expression of cytokine genes in human lymphoma cells in vitro has been demonstrated. In order to extend these experiments in vivo, highly tumorigenic Burkitt's lymphoma (BL) cells were transfected with different cytokine genes of human and murine origin cloned into the EBNA 1/ori P vectors. Tumorigenicity of the transfectants was measured after inoculation into nude mice. No effect on tumorigenicity was observed after hIL 6 transfection and an inconsistent effect after hTNFalpha transfection. In contrast, complete suppression of tumor outgrowth occurred in hIL 10 transfectants. This tumor suppressive effect, however, was restricted to the IL 10 transfectants themselves and not directed against non-transfected cells. By comparison, mIL 4 transfected BL cells also were non-tumorigenic. However, co-inoculation of mIL 4 transfected and non transfected cells resulted in suppression of the tumorigenicity of the non-transfected cells. Thus, highly tumorigenic BL cells in nude mice are sensitive to immune effector mechanisms triggered by cytokine expression. In this experimental model, EBNA 1/ori P expression vectors are a suitable tool for cytokine gene transfer mediated induction of an anti-lymphoma immune response of the host.

Expression of tumor necrosis factor-alpha and interleukin-6 in oral squamous cell carcinoma

To explore the role of cytokines in tumor development and clinical manifestations, we examined the expressions of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in tumor tissues obtained from 57 patients with oral squamous cell carcinoma (OSCC) and their relationships to pathological grade and staging. Enzyme-linked immunosorbent assay on the tumor tissues demonstrated elevated concentrations of TNF-alpha and IL-6 proteins and upregulated mRNA levels were detected by the reverse transcription-polymerase chain reaction method when compared to those in normal control tissues. These cytokines and their transcripts were localized in stromal macrophages and in the tumor cells in particular of the front area of tumor tissues, possibly indicating active synthesis of these cytokines by tumor cells. Larger-sized tumors (T3, 4) contained significantly greater levels of IL-6 proteins than small-sized tumors (T1, 2) (P<0.05). The levels of these cytokines were significantly reduced in cases with effective pre-treatment with radiation or anti-cancer agents compared to those in the less effective group (P<0.05, grade IIa vs. grade IV for both TNF-alpha and IL-6). The present study thus demonstrated enhanced expression of cytokines in OSCC tissues.

Marked elevation of serum interleukin-6 in patients with cholangiocarcinoma: validation of utility as a clinical marker

OBJECTIVE

To determine if the serum level of interleukin-6 (IL-6) was elevated in patients with hepatic malignancies or correlated with radiologic tumor burden.

SUMMARY BACKGROUND DATA

High serum levels of IL-6 signify an adverse prognosis in many patients with cancer. IL-6 is a growth factor for bile duct epithelium.

METHODS

Using bioactive and enzyme-linked immunosorbent assays, serum level of IL-6 was measured in 35 healthy adults and in 60 patients presenting for definitive management of cholangiocarcinoma (CC) (15 patients), hepatocellular carcinoma (HCC) (14), metastatic colorectal cancer (MCRC) (26), and benign biliary disease (BBD) (5). Patients with clinical conditions known to raise the serum level of IL-6 were excluded. Tumor burden was calculated from concurrent computed tomography scans. IL-6 levels were measured 2 weeks after resection in 3 CC patients. Secretion of IL-6 was examined in 3 human CC cell lines.

RESULTS

An elevated level of bioactive IL-6 was detected in every patient with CC and in 13 of 14 patients with HCC, 14 of 26 patients with MCRC, 2 of 5 patients with BBD, and 3 of 35 healthy adults. Median and mean levels of bioactive IL-6 were higher in CC than in other neoplasms (p < 0.026) and for all tumor groups differed from healthy adults (p < or = 0.026). IL-6 level was elevated more often in primary than in secondary liver neoplasms (p = 0.02), distinguished patients with CC or MCRC from BBD (p = 0.014 and 0.031, respectively), correlated with tumor burden in CC (p < 0.001), and dropped sharply after CC resection. CC line SG231 secreted bioactive IL-6.

CONCLUSIONS

In selected patients, a high serum level of IL-6 marks patients with CC and correlates with tumor burden both before and after resection. IL-6 levels are elevated in patients with other liver neoplasms and may distinguish patients with hepatic malignancies from those with benign disease.

Improvement by eicosanoids in cancer cachexia induced by LLC-IL6 transplantation

Cachexia frequently occurs in the late stages of cancer, and is difficult to manage. We previously reported that interleukin-6 (IL-6) cDNA transfection into Lewis lung carcinoma (LLC-IL6) induced cachexia-like symptoms in C57BL/6 mice. This was thought to be a useful experimental model of cancer cachexia. We have examined the effects of two eicosanoids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), in order to evaluate whether they could relieve cachexia. LLC-IL6-bearing animals were divided into three treatment groups receiving DHA, EPA or water as the control; 80-microliter samples of these compounds (purity > 95%) were administered orally by catheter daily starting 7 days after tumor transplantation. Tumor growth curves were similar in the three groups. There were no differences in water or food intake in the three groups. However, body weight, a marker of cachexia, was significantly higher in treated mice than in the control group. Sixteen days after tumor transplantation, the mean body weight was 17.45 g (P < 0.05), 17.2 g and 16.41 g in the groups receiving DHA, EPA and water respectively. The eicosanoids did not affect serum levels of IL-6. Ubiquitination of muscle protein, a marker of proteolysis coupled to cachexia, was compared in LLC-IL6- and LLC-transplanted mice. The eicosanoids prevented the ubiquitination of approximately 180 kDa protein. These results suggest that eicosanoids may prevent the cachexia mediated by IL-6.

Granulocyte-macrophage colony-stimulating factor inhibits tumor growth during the postoperative period

BACKGROUND

Granulocyte-macrophage colony-stimulating factor (GM-CSF) may have important antineoplastic properties because it induces macrophage tumoricidal activity in vitro. We examined the inhibitory effect of GM-CSF on tumor growth in a murine carcinoma model and whether this inhibitory effect would persist during the postoperative period. Potential macrophage-mediated mechanisms were studied.

METHODS

The effect of GM-CSF on macrophage function in vitro was assessed by measuring superoxide anion and interleukin-6 production, percentage phagocytosis of Candida albicans, and percentage Ia expression. GM-CSF's effect on tumor volume was assessed first in a murine tumor model and second to examine whether these effects also occurred during the postoperative period in the same model after laparotomy. Macrophage function in the latter study was assessed by measuring superoxide anion, cytotoxicity, and tumor necrosis factor production.

RESULTS

GM-CSF treatment was associated with a decrease in tumor volume on day 4 after the initiation of GM-CSF treatment (0.93 +/- 0.08 cm3 for control versus 0.34 +/- 0.08 cm3 for GM-CSF; p < 0.05). This effect was also seen after laparotomy (1.07 +/- 0.2 cm3 for laparotomy+saline versus 0.16 +/- 0.04 cm3 for laparotomy+GM-CSF, p < 0.05). In vivo macrophage function showed increased superoxide anion, cytotoxicity, and tumor necrosis factor-alpha production from macrophages obtained from GM-CSF treated animals compared with saline treated controls.

CONCLUSIONS

Tumor growth is inhibited by GM-CSF treatment, and this effect also occurs after laparotomy. Thus, GM-CSF may have a therapeutic role in the treatment of the tumor bearing host after operation.

Suppression of Burkitt's lymphoma tumorigenicity in nude mice by co-inoculation of EBV-immortalized lymphoblastoid cells

EBV-immortalized B-lymphoblastoid cell lines (LCL) inoculated s.c. into T-cell-deficient nude mice regress completely after a short initial growth period. We tested whether the putative host response underlying this phenomenon might also be directed against progressively growing Burkitt's lymphoma (BL) tumors in nude mice. Outgrowth of BL tumors was suppressed when cells of the highly tumorigenic BL cell line BL 60 were mixed with cells of the autologous LCL IARC 277 before s.c. inoculation into nude mice. Even when the cells were inoculated separately and simultaneously into contralateral flanks of the mice, regression of initially growing BL tumors could be observed, albeit with reduced frequency and dependent on the dose of LCL cells. Tumor growth of BL 60 cells could also be suppressed by co-inoculation with the non-autologous LCL IARC 174 and IARC 277 cells could suppress growth of the non-autologous BL cell line Eli. Pronounced infiltration with murine (m)CD-11b-positive mouse macrophages and mCD-8a-positive mouse lymphoid cells, most probably natural killer cells, was seen in histological tissue sections of regressing BL 60 tumors when LCL cells were inoculated contralaterally. In regressing BL tumors, these mouse cells were present not only in necrotic areas but also in vital BL tissue, indicating that infiltration of mouse cells had taken place before the development of necrosis. Since tumor-infiltrating mouse cells can be activated at least by some human cytokines, we measured cytokine production of BL 60 and IARC 277. High amounts of IL 6 and IL 10 were produced by the LCL cells, whereas IL-6 and IL-10 production by the BL 60 cells was beyond or close to the detection threshold. In addition, IL 8 was secreted up to 5-fold more by the LCL than by the BL cells. The results presented here thus suggest a host response of the nude mouse, which is triggered by cytokines released from the LCL but, once induced, is directed also against BL cells.

Immune function of patients receiving recombinant human interleukin-6 (IL-6) in a phase I clinical study: induction of C-reactive protein and IgE and inhibition of natural killer and lymphokine-activated killer cell activity

Interleukin-6 (IL-6) is a cytokine that acts on a variety of cell types, including myeloid progenitor cells and B and T lymphocytes. It has been found to activate cytotoxic T cells and natural killer (NK) cells and to induce T-cell-mediated antitumour effects in animal models. In a phase I clinical trial of recombinant human IL-6, 20 patients with advanced cancer were entered to receive daily subcutaneous injections of IL-6 over 7 days followed by a 2-week observation period and another 4 weeks of daily IL-6 injections. Doses varied between 0.5 microgram/kg and 20 micrograms/kg body weight and immune functions were monitored throughout. At all dose levels IL-6 administration led to a marked increase in serum levels of C-reactive protein and a moderate rise in complement factor C3. The proportions of CD4, CD8 or HLA-DR lymphocytes in peripheral blood did not alter with IL-6 treatment nor did the in vitro proliferation of peripheral blood mononuclear cells induced by either phytohaemagglutinin, pokeweed mitogen or fixed Staphylococcus aureus. By contrast, NK cell activity, lymphokine-activated killer (LAK) cell activity and proliferation induced by in vitro culture with interleukin-2 (IL-2) were suppressed at doses exceeding 2.5 micrograms/kg. Serum IgE levels were consistently elevated over the IL-6 dose range but IgM, IgG and IgA levels were unaffected. In summary there is a dose-dependent induction of acute-phase proteins by in vivo IL-6 treatment. At higher IL-6 doses there is a suppressive effect on NK and LAK activity measured in vitro. IL-6 may thus be useful in combination cytokine therapies that seek to suppress LAK and favour cytotoxic T lymphocyte responses. The rise in IgE levels in response to IL-6 was unexpected and suggests a more pivotal role than previously known for the control of IgE production; this could include IgE-related diseases.

Induction of serum tumor necrosis factor-alpha and interleukin-6 activity by liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (L-MTP-PE) in normal cats

Tumor necrosis factor-alpha (TNF alpha) and interleukin-6 (IL-6) are products of activated monocytes/macrophages with anti-tumor activity. Liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (L-MTP-PE) is a potent monocyte/macrophage activator. Sera from cats after intravenous L-MTP-PE administration showed TNF alpha activity using a WEHI-164 cell cytotoxicity assay and IL-6 activity using an IL-6 dependent mouse 7TD1 hybridoma cell proliferation assay. Serum TNF alpha activity peaked at 2 hours after L-MTP-PE administration. Significant differences from lipid-equivalent controls were observed at 2 and 3 hours (P < 0.05). Neutralization of serum TNF alpha activity was accomplished with serial dilutions of rhTNF alpha monoclonal antibody. Serum IL-6 activity peaked at 3 hours after L-MTP-PE administration. Significant differences from lipid-equivalent controls were observed at 2, 3, and 4 hours (P < 0.05). Neutralization of serum IL-6 activity was not achieved with goat anti-rhIL-6 polyclonal antibody. Intravenous L-MTP-PE, but not lipid-equivalent, induces serum TNF alpha and IL-6 activity in normal cats.

Coley's toxins, tumor necrosis factor and cancer research: a historical perspective

As far back as the 1700s, it was recorded that certain infectious disease processes could exert a beneficial therapeutic effect upon malignancy. Most prominent among the numerous deliberate efforts made to take advantage of these observations was that of a pioneering New York surgeon, William B. Coley, active career 1891-1936. Using a bacterial vaccine to treat primarily inoperable sarcoma. Coley accomplished a cure rate of better than 10%. This review examines the history of these efforts and presents a discussion of their corresponding relevance to present day immunotherapy.

Effect of allogeneic tumor cells, interleukin-2 and interleukin-6, on the growth of subcutaneous syngeneic tumors

In the present study we demonstrate the ability of allogeneic M3 tumor cells to induce an antitumor response against the syngeneic tumor, when injected locally together with syngeneic B16 melanoma cells. The replacement of the allogeneic tumor cells with either syngeneic or allogeneic splenocytes had no effect on the growth of the syngeneic tumor. Systemic administration of both interleukin-2 (IL-2) and IL-6 did not affect the antitumor response induced by allogeneic tumor cells. When mice, previously injected with B16 and M3 cells, were rechallenged subcutaneously with B16 tumor cells at a different anatomical site, an inhibitory effect in some, but not all, experiments was observed. Systemic injections of either IL-2 or IL-6 did not alter the antitumor effects of the allogeneic and syngeneic tumor-cell mixtures. The significance of our results in developing immunotherapy modalities based on active immunization with allogeneic tumor cells and selected cytokines is discussed.

Individual diversity of IL-6 generation by human monocytes with lentinan administration

Effect of in vivo administration of lentinan on IL-6 generation by human peripheral blood monocytes was examined using 5 healthy volunteers. Monocytes isolated from them before and 3 days after intravenous administration of 2 mg lentinan per person were cultured for 2 days and then the levels of IL-6 in the supernatants of cultured monocytes were determined. In vivo lentinan administration elicited an increase in IL-6 generation by monocytes in 3 of 5 cases. Failure to increase IL-6 generation by monocytes in two cases is characteristic of lentinan, since these monocytes generated an apparent level of IL-6 in response to lipopolysaccharide, a potent monocyte activator. Thus, it was demonstrated that lentinan was capable of augmenting IL-6 generation by human monocytes and that there was individual difference in their responsiveness to lentinan.

Interleukin-6 cDNA transfected Lewis lung carcinoma cells show unaltered net tumour growth rate but cause weight loss and shortened survival in syngeneic mice

HuIL-6 cDNA, cloned into a neomycin resistant conferring expression vector, BMGNeo, was transfected into Lewis Lung Carcinoma (LLC) cells. LLC cells (5 x 10(6) ml-1) transfected with IL-6 cDNA (LLC-IL6) secreted IL-6 into the culture supernatant at a concentration of 9.9 ng ml-1 within 48 h. When 1,000,000 of untransfected LLC, BMGNeo vector transfected LLC (LLC-Neo) or LLC-IL6 cells were transplanted into C57BL/6 mice subcutaneously, the mean +/- s.d. of survival times of these mice were 33.3 +/- 9.7, 34.3 +/- 7.1 and 17.0 +/- 3.1 days, respectively. The survival time of LLC-IL6 cells transplanted mice was significantly shorter than that of LLC (P < 0.01) or LLC-Neo (P < 0.01) cells transplanted mice without a measurable difference of tumour size. Plasma concentration of IL-6 steadily increased in LLC-IL6 transplanted mice. Body weight and serum albumin were significantly lower in LLC-IL6 transplanted mice than in LLC transplanted mice. Mouse IL-1 alpha and mouse TNF-alpha were not detected in the plasma of LLC-IL6 transplanted mice. These data suggested that secretion of IL-6 from LLC cells was unable to alter net tumour growth rate but rather caused a state similar to cachexia without detectable increase of IL-1 alpha and TNF-alpha in the plasma. This state may be responsible for the shortened survival of LLC-IL6 tumour-bearing mice.

Combined therapy with IL-6 and inactivated tumor cells suppresses metastasis in mice bearing 3LL lung carcinomas

We investigated the anti-tumor effects of human recombinant interleukin-6 (hrIL-6) on the highly metastatic Lewis lung-carcinoma clone, D122. These cells express high-affinity IL-6 receptors at numbers comparable to the IL-6-dependent murine hybridoma B9 cells; however, IL-6 did not affect D122 cell proliferation or expression of MHC-class-I antigens in vitro. In vivo, treatment of mice bearing D122 tumors in the footpads, with a low dose of IL-6 in 3 daily injections, 4 days a week for 3 weeks, significantly decreased spontaneous metastases. However, only combined treatment of IL-6 and irradiated tumor cells resulted in almost complete protection against spontaneous metastases. Histological analysis confirmed the absence of micrometastases in most of the animals treated by this combination protocol. Analysis of the cytolytic activity of splenocytes at various time points during combined IL-6 and immunotherapy of tumor-bearing mice revealed significant and sustained lysis of the poorly immunogenic D122 carcinoma cells, while splenocytes of control mice could not lyse D122 target cells. Activation of specific immunity was also demonstrated when mice were pre-immunized with hrIL-6 and inactivated D122 cells and challenged with live carcinoma cells 10 days later. Significant growth inhibition of the primary tumor was observed.

Antitumor effects of recombinant interleukin-6 expressed in eukaryotic cells

In the present study we evaluate the antitumor efficacy of a glycosylated molecule of interleukin-6 (IL-6), which was cloned and expressed in Chinese hamster ovary cells. When tested with two syngeneic murine tumors, the MC38 adenocarcinoma and the MCA106 fibrosarcoma, recombinant IL-6 (rIL-6) significantly reduced the number of day-3 established MC38 lung metastases, but had no effect on MCA106 lung metastases. A similar effect of rIL-6 was seen on day-3 MC38 liver metastases. The antitumor activity mediated by rIL-6 was achieved at doses of the cytokine ranging from 6 micrograms to 150 micrograms/day. There was no correlation between the responsiveness to rIL-6 of these two tumors and their susceptibility, in vitro, to a direct cytostatic effect of the cytokine or the increase in the expression of major histocompatibility complex (MHC) antigens after exposure to rIL-6. However, a correlation was seen between the antitumor response to rIL-6 and the initial number of tumor cells expressing MHC antigens. The possible role of MHC antigens expressed on tumor cells, the generation of MHC-restricted cytotoxic cells and the responsiveness to IL-6 are discussed.

Tumour cell inhibition of macrophage cytokine activity

Macrophages elaborate both effector and regulatory immune functions. It was hypothesised that tumours can exert a local alteration of macrophage function. Murine peritoneal macrophage-derived cytokines were assayed in the presence and absence of cells, cytosol fractions or conditioned media (TCCM) from established murine tumour lines. Interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha activities were significantly inhibited by tumour cells or their products, as were the corresponding recombinant human cytokines. Intracellular protein kinase C activation was also measured and was significantly inhibited by murine TCCM, thus suggesting one possible site of inhibitor action. Data analyses indicate that the inhibitory factor(s) is probably not an already well-characterised macrophage inhibitor.

In vivo effects of recombinant human interleukin 6, alone or in combination with local irradiation, on tumor growth in Lewis lung carcinoma-bearing mice

Lewis lung carcinoma (LLC)-bearing mice were used as a mouse model to evaluate effects of recombinant human (rh) interleukin (IL) 6 and local X-irradiation (LR) on the growth of primary tumors and lung metastases. Mice were inoculated s.c. with LLC tumor cells and then treated with rhIL-6 (100 ng/dose) s.c. twice a day (b.i.d.) for 5 days, beginning 6 days after tumor inoculation. LR (800 cGy) was administered to the site of the primary tumor 6 days after tumor inoculation and again 1 wk later. Mice were then observed for survival or sacrificed at day 21 after tumor inoculation to determine size of primary tumor, numbers and size of lung metastases, and other hematological parameters including numbers of granulocyte-macrophage progenitor cells (CFU-gm). The size of the primary tumor and numbers of lung metastases were reduced by rhIL-6. LR enhanced the antitumor effect of rhIL-6 significantly, while LR alone had only a slight antitumor effect. Tumor-associated increases in peripheral blood, femoral marrow, splenic-nucleated cellularity, and marrow and splenic CFU-gm were reduced in mice treated with rhIL-6 plus LR. Prolonged survival time was observed only in tumor-bearing mice treated with rhIL-6 in combination with LR. The antitumor effects in vivo of rhIL-6 appear to be mediated indirectly as rhIL-6 had no effect on proliferation of LLC cells in vitro as assessed by colony and 3H-thymidine incorporation assays. These studies suggest that rhIL-6 may have therapeutic value in the treatment of certain malignancies, especially if used in combination with LR.