血小板生成素与白介素-11治疗胃癌术后辅助化疗后血小板减少症时效及安全性的比较

目的:比较血小板生成素与白介素-11治疗胃癌患者术后化疗血小板减少症的时效和安全性。方法:术后辅助化疗出现血小板计数低于75×109/L的进展期胃癌患者68例,将其分为TPO组与IL-11组,分别为35例和33例。分别皮下注射rhTPO 15000U,每日1次;rhIL-11 1.5 mg,每日1次,当血小板计数125×109/L或比用药前上升50×109/L,即停止给药,疗程最长为14天。每3天抽取外周静脉血2 m L,通过全自动血液分析仪测定血小板计数,密切观察出现的不良反应并记录。比较两组患者不同临床病理资料、血小板计数、血小板计数升至75×109/L和125×109/L的时程、药物不良反应。结果:两组患者年龄、性别、化疗方案、血小板最低值出现的化疗周期及临床病理分期的比较均没有统计学差异(P值均0.05)。TPO组与IL-11组血小板动态值的比较,第9天出现显著差异(P=0.032)。TPO组与IL-11组血小板计数恢复至75×109/L和125×109/L所需的时间,有显著差异(P=0.041,P=0.013)。TPO组中,有3例(8.6%)患者发生不良反应,IL-11组中,有13例(39.4%)患者发生不良反应,TPO组患者出现的不良反应少且较轻微(P=0.006)。结论:rhTPO治疗胃癌患者术后化疗血小板减少症时效快,安全性好。     

Kinetic analysis of megakaryopoiesis induced by recombinant human interleukin 11 in myelosuppressed mice

Recombinant human interleukin 11 (rhIL-11) has previously been shown to ameliorate thrombocytopenia in several animal models. To elucidate the mechanisms involved in rhIL-11-induced hematopoiesis, a kinetic analysis of megakaryopoiesis was performed in mitomycin C (MMC)-induced myelosuppressive mice. Mice intravenously injected with MMC (2 mg/kg) for two consecutive days from day -1 developed severe thrombocytopenia with a nadir of platelet counts at 24x10(4)/microl on day 12 and neutropenia. Treatment with rhIL-11 (500 microg/kg/day) from day 1 to 21 significantly ameliorated the degree and duration of thrombocytopenia and enhanced the platelet recovery, and also enhanced the recovery from neutropenia. In MMC-treated mice, the decreases in bone marrow megakaryocyte progenitors and megakaryocyte counts preceded the decrease in platelet counts by MMC treatment. RhIL-11 induced an increase in the number of megakaryocyte progenitors from day 4 to 14, followed by an increase in the megakaryocytes by day 20. There was a ploidy shift in megakaryocytes towards lower ploidy cells by day 9 in myelosuppressed mice. RhIL-11 caused a shift towards a higher ploidy with 32 and 64N on day 4, and 32N on day 14. These results suggest that rhIL-11 ameliorates the thrombocytopenia via the stimulation of both the maturation and commitment followed by the proliferation of megakaryocytic cells.     

Inhibition of the calcitonin-induced outward current in identifiedAplysia neurons by interleukin-1 and interleukin-2

Summary 1. The effects of bath-applied recombinant human interleukin-1 (rhIL-1) and interleukin-2 (rhIL-2) on the calcitonin (CT)-induced outward current recorded from identified neurons (R9–R12) ofAplysia kurodai were investigated with conventional voltage-clamp and pressure ejection techniques.2. Micropressure ejection of CT onto the soma of the neuron induced a slow outward current [I _o(CT); 4–6 nA in amplitude, 30–40 sec in duration] associated with a decrease in input membrane conductance.3.I _o(CT) was increased by hyperpolarization.4. The extrapolated reversal potential was +10 mV. Additionally,I _o(CT) was sensitive to changes in (Na⁺)_o but not to changes in (K⁺)_o, (Ca²⁺)_o, and (Cl^–)_o.5. Micropressure-ejected forskolin produced a slow outward current similar to that induced by CT.6. Bath-applied rhIL-1 and rhIL-2 (10–40 U/ml) reduced the CT-induced current in identifiedAplysia neurons without affecting the resting membrane conductance or the holding current.7. The inhibitory effects of both cytokines on the current were completely reversible. Heat-inactivated rhIL-1 and rhIL-2 were without effect.8. These results suggest that the immunomodulators, IL-1 and IL-2, can modulate the CT-induced outward current associated with a decrease in Na⁺ conductance in the nervous system ofAplysia. Therefore, the study suggests that these cytokines may also serve as neuromodulators.     

Interleukin-12 genetic administration suppressed metastatic liver tumor unsusceptible to CTL

A cytokine gene therapy approach was conducted against metastatic lesions of cytotoxic T lymphocyte (CTL)-unsusceptible tumor in mice. The EBV-based and conventional plasmid vectors that encode murine interleukin-12 (IL-12) gene (pGEG.mIL-12 and pG.mIL-12, respectively) were intravenously transfected into the mice that had received a subcutaneous inoculation of M5076 sarcoma cells. The pGEG.mIL-12 transfection drastically suppressed the subcutaneous as well as hepatic metastatic tumors, resulting in significant prolongation of survival period of the animals. Although single administration with pG.mIL-12 was not effective, repetitive transfection with the plasmid significantly prolonged the longevity of the mice-bearing the metastatic liver tumors. Multiple transfection with either pGEG.mIL-12 or pG.mIL-12 also suppressed peritoneal carcinomatosis in mice that had been injected with M5076 cells into the peritoneal cavity. It was suggested that a high level IL-12 production elicited by the intravenous delivery of the cytokine gene may be quite effective in inhibiting metastatic and CTL-unsusceptible neoplasms.     

Effects of IFN on human eosinophils in comparison with other cytokines. A novel class of eosinophil activators with delayed onset of action.

Extracellular killing is regarded as one of the main functions of eosinophils. Therefore, a cytotoxicity assay against antibody-coated Daudi-lymphoma cells was established to measure cytokine effects on peripheral blood eosinophils from healthy volunteers. Optimal time of exposure to cytokines and half optimal concentrations (EC50) were determined and the capability of various cytokines to enhance cytotoxicity of eosinophils was compared. Thus, after 24 h with cytokine, the highest activation of eosinophils was observed with recombinant human rhIFN-gamma (EC50 = 0.2 U/ml), followed by the known activators of eosinophils recombinant human granulocyte/macrophage CSF (rhGM-CSF), rhIL-3, and murine IL-5 (mIL-5). rhIFN-alpha and natural human IFN-beta (nhIFN-beta) enhanced cytotoxicity as well. On the other hand, in short term assays, eosinophils were not stimulated by IFN and the strongest stimulator was rhGM-CSF (EC50 = 0.2 U/ml), followed by rhIL-3, mIL-5, rhTNF, and rhIL-4. With rhTNF-alpha enhancement was more pronounced on freshly isolated eosinophils (EC50 = 0.6 U/ml) and declined with time. No significant stimulation was detected with rhG-CSF, rhIL-1 beta, rhIL-2, rhIL-6, and rhIL-8. On neutrophils, rhIL-8 enhanced cytotoxicity, but the stimulation was weak in relation to other neutrophil activators. Studies on the mechanism of cytotoxic activity revealed that cytotoxicity required opsonization of targets with specific antibody. FMF analysis was performed demonstrating that freshly isolated eosinophils express Fc-gamma RII (CD32), small amounts of Fc-gamma RIII (CD16), but not Fc-gamma RI (CD64). In experiments with blocking antibodies to Fc-gamma R cytotoxicity was restricted to Fc-gamma RII. Expression of Fc-gamma RII was not enhanced by rhGM-CSF, rhTNF-alpha, and mIL-5, but a significant increase in the number of positive cells was observed after incubation with rhIFN-gamma for 24 h (p less than 0.05). In addition, enhanced viability of eosinophils was observed when cultured in the presence of rhIFN-gamma, rhIFN-alpha, rhGM-CSF, and rhTNF-alpha, but not of rhG-CSF and rhIL-2. Thus, IFN appear to be another class of activators of eosinophils, characterized by their delayed type of action.     

抗人IL-6单克隆抗体的制备及鉴定

用基因重组人IL-6免疫Balb/c小鼠,采用小鼠杂交瘤技术,筛选克隆到分泌抗人重组IL-6单克隆抗体的杂交瘤细胞株,并对其中2H₂、 1D₂ 和4B₄瘤细胞株进行了鉴定.其抗体类别均为IgG,亚类分别为IgG1和IgG2a.用多种细胞因子和无关蛋白的鉴别试验结果证实它们均特异地识别rhIL-6.免疫转染结果显示,该单抗识别分子质量为21 ku的IL-6单一条带.IL-6单克隆抗体的亲和常数K_aff= 1.62×10⁹ (mol/L)^-1.     

Interleukin-5 induces tumor suppression by peritoneal exudate cells in mice

The antitumor activity of peritoneal exudate cells (PEC) induced by murine interleukin-5 (mIL-5) was examined using Meth-A sarcoma cells transplanted into the peritoneal cavity of mice. Although in vitro treatment of Meth-A sarcoma cells with mIL-5 did not result in inhibition of their growth, treatment of mice intraperitoneally with mIL-5 (1 g/day) from day –5 to +5 (tumor cells were inoculated on day 0) led to a significant increase in survival or even rejection of tumor cells. This antitumor effect depended on the dose of mIL-5. Interestingly, there was identical therapeutic activity when the protocol of days –10 to –1 was used as opposed to –5 to +5. In addition, post-treatment with mIL-5 from day +1 to +10 was ineffective. This suggests that the therapeutic activity of IL-5 is largely prophylactic. Under the former condition, the number of PEC was found to increase over 50-fold when compared to levels in control mice. Moreover, the antitumor effect of mIL-5 was completely abolished by subcutaneous injection of anti-mIL-5 monoclonal antibodies. The treatment of mice injected intraperitoneally with human IL-2 also resulted in an increase in survival. Winn assay experiments using PEC recovered from mIL-5-treated mice (1g/day, from day –10 to –1) revealed that these PEC could mediate antitumor activity against Meth-A sarcoma cells. Furthermore, when the cured mice were re-injected with Meth-A sarcoma cells or syngeneic MOPC 104E cells, they could reject Meth-A sarcoma cells but not MOPC 104E cells, indicating that immune memory had been generated. These results suggest that IL-5 augumented the PEC tumoricidal activity but we have no indication that the tumoricidal activity was mediated through a mIL-5-dependent mechanism.     

Enhanced Secretion of Biologically Active Murine Interleukin-12 by Lactococcus lactis

The novel signal peptide SLPmod was used for the secretion of murine interleukin-12 (mIL-12) by Lactococcus lactis. A >4-fold increase in secretion was observed when SLPmod was used instead of the Usp45-derived secretion signal. Oral delivery of this cytokine using the autoinducible host L. lactis FI5876 utilizing SLPmod resulted in a significant increase in mIL-12 plasma levels in mice.     

Secretion of biologically active murine interleukin-10 by Lactococcus lactis

We investigated the ability of Lactococcus lactis to secrete biologically active, murine interleukin-10 (mIL-10). mIL-10 was synthesized as a fusion protein, consisting of the mature part of the eukaryotic protein fused to the secretion signal of the lactococcal Usp45 protein. The secreted protein was analyzed by PAGE, ELISA and bioassay.We show that L. lactis can efficiently secrete biologically active, murine IL-10. Determination of the N-terminal amino acid sequence confirmed correct processing of the fusion polypeptide by the lactococcal signal peptidase. The amount of mIL-10, accumulating in the medium, could be increased by a factor of ten by growing the cells in an optimized medium, buffered at near-neutral pH. Under these conditions, up to 30 mg of mIL-10 was obtained from a 10-litre fermentation.     

Mechanism of the antiulcerogenic effect of IL-11 on acetic acid-induced gastric ulcer in rats

The purpose of this study was to evaluate the healing effect of interleukin-11 (IL-11) on acetic acid-induced gastric ulcer in rats. Gastric ulcers were induced in male Wistar rats by applying acetic acid to the fundus of the stomach. Recombinant human interleukin-11 (rhIL-11 100 microg/kg/twice daily, subcutaneously) was administered starting on the 2nd day before ulcer induction up through the 7th day after ulcer induction. Control rats were injected with bovine serum albumin. At 12 hours and 7 days after ulcer induction, the animals were sacrificed, and the ulcer index, proliferating cell nuclear antigen (PCNA) expression, and IL-11alpha receptor expression in the gastric tissues were studied. The ulcer index of the rhIL-11-treated rats was significantly lower than that of the control rats at the 7th day. The expression of PCNA as evaluated by Western blotting and immunohistochemistry, was enhanced in both the mucosal proliferative zone and proper muscle layer of the rhIL-11-treated rats in comparison with that in the control rats. IL-11alpha receptor expression was observed in the mucosal neck cells of the rhIL-11-treated rats and control rats. These findings suggest that IL-11 accelerates ulcer healing by inducing the proliferation of mucosal and muscular cells.     

An establishment of ELISA for murine IL-6

Summary Murine interleukin-6 (mIL-6) was expressed inEscherichia coli as human growth hormone (hGH) fusion protein. The products were cleaved by thrombin to liberate mIL-6. Monoclonal and polyclonal antibodies specific to mIL-6 were prepared by immunizing rats with mIL-6 thus obtained. ELISA for the quantitation of mIL-6 was also established, which could detect mIL-6 in a quantity as low as 2 ng/ml.     

人白细胞介素11的定点聚乙二醇修饰

利用人白细胞介素11（hIL-11）无半胱氨酸（Cys）残基这一特点,通过定点突变将一个Cys残基引入hIL-11的N末端。然后,利用与Cys 巯基特异性反应的mPEG-马来酰亚胺将mPEG偶联到预先选定的位点,经层析纯化得到hIL-11的定点PEG修饰物。利用依赖型细胞株7TD1测定其生物学活性,结果表明,其体外生物学活性保持原有hIL-11活性的30%左右。定点聚乙二醇修饰方法为定向改造hIL-11,提高其药效的应用研究打下基础。     

Pretreatment with recombinant human interleukin 2 (rhIL-2) Up-regulates PCNA-positive cells after partial hepatectomy in rat liver

We prepared recombinant human interleukin-2 (rhIL-2) and studied its pretreated influence on liver regeneration and the blood profile in partially (67%) hepatectomized (PH) male Sprague-Dawley rats. Rats were injected in the tail vein with rhIL-2 three times per day for 3 consecutive days and 67% underwent a partial hepatectomy (PH). Five days after the PH, liver tissue and blood samples were analyzed for liver regeneration and hematological changes. The weight of the liver in the rhIL-2 pretreated groups increased in a dose-dependent manner; with the highest treatment (24 × 10⁴ IU/kg), the maximum liver weight of 88.6% was exhibited. The control group showed a gradual increase to 76.3% of the original liver weight. A histological analysis of the liver showed an increase in proliferating cell nuclear antigen (PCNA)-positive cells in rhIL-2 pretreated rat livers. The rate of hepatocyte proliferation also increased significantly in primary cultured rat liver cells following rhIL-2 treatment. These results suggest that pretreatment with rhIL-2 may play adjuvant roles in liver regeneration after PH.     

Clinical use of recombinant human hematopoietic growth factors (GM-CSF, IL-3, EPO) in patients with myelodysplastic syndrome.

We have conducted several phase I/II clinical studies in a total of 65 MDS patients utilizing recombinant human hematopoietic growth factors including GM-CSF, IL-3, and EPO. Twenty-seven patients with MDS were treated with either continuous i.v. infusion or single daily s.c. injection of rhGM-CSF at dosages from 15 micrograms/m2 to 1000 micrograms/m2. All of them exhibited white cell responses during the treatment cycles, but no sustained rise in reticulocytes or platelets was recorded. In four of the patients, all with > or = 15% blast cells in the bone marrow, the percentage of circulating blast cells increased during treatment with rhGM-CSF (at dosages of 500 micrograms/m2 and 1000 micrograms/m2, respectively), although no leukemic conversion occurred. Of 9 patients treated so far with rhIL-3 at single daily s.c. dosages of 60 micrograms/m2, all exhibited white cell responses; 8 exhibited significant improved platelet and reticulocyte counts. Nineteen further patients received rhEPO for a period of 14 weeks by s.c. (10,000 U five times weekly) or i.v. bolus administration (150-450 U/kg). None of these patients experienced an increase in white cell and platelet counts. A significant increase of the reticulocyte count was recorded in 3 patients only. Another strategy involves the recruitment of leukemic cells into the cell cycle by hematopoietic growth factors followed by treatment with cycle-specific cytostatic agents. Therefore in 10 patients administration of rhGM-CSF (250 g/m2/day x 14, s.c.) was combined with Ara-C treatment (20 mg/m2/day x 14; s.c.). Initial results of this pilot study available in 5 patients indicated that this approach may control leukemic cell proliferation and may increase number of mature myeloid cells in both bone marrow and peripheral blood. A similar approach utilizing rhIL-3 in conjunction with Ara-C is on-going.     

Expression of a bioactive recombinant human interleukin-11 in chicken HD11 cell line

To direct the synthesis and secretion of recombinant human interleukin-11 (rhIL-11) in chicken HD11 cells, a plasmid targeting the c-lysozyme gene has been constructed which contains the mature cytokine cDNA in frame with the lysozyme leader sequence. The upregulation of rhIL-11 mediated by LPS proves the knock-in of hIL-11 cDNA in the lysozyme gene. The bioactivity of the expressed protein is demonstrated and quantified with the hIL-11 dependent 7TD1 and B9 cell lines. The electrophoretic mobility, receptor binding properties and growth promoting effect of the chicken-derived cytokine are identical to those of a rhIL-11 expressed in Escherichia coli. These results describe the secretion of a biologically active rhIL-11 expressed by an avian cellular machinery.     

Identification of the interleukin-3 receptor using an iodinatable, cleavable, photoreactive cross-linking agent

Murine interleukin-3 (mIL-3) is a lymphokine that stimulates the proliferation and differentiation of both pluripotent hemopoietic stem cells and their committed progeny. However, very little is known about the mechanism by which this growth factor elicits its effects on responsive cell populations. To gain insight into early events following mIL-3 receptor interaction, we initiated studies to isolate the receptor and study its properties. In this report, we demonstrate the use of a new iodinatable, cleavable, photoreactive cross-linking agent, sulfosuccinimidyl 2-(p-azidosalicylamido)-1,3'-dithiopropionate to identify the mIL-3 receptor. These studies reveal the mIL-3 receptor to be a single polypeptide chain with a molecular weight of 67 kDa and an isoelectric point of approximately 6.2.     

Effect of recombinant human interleukin-11 on motilin and substance P release in normal and inflamed rabbits

Recombinant human interleukin-11 (rhIL-11) normalizes depressed smooth muscle tension generation towards motilin and substance P (SP) in rabbits with colitis. The aim of this paper was to evaluate the effect of rhIL-11 treatment on motilin and SP release which could have an effect on the contractility changes. Rabbits received 4, 40, 72 or 720 microg/kg rhIL-11 s.c. or saline, 1 h later a continuous s.c. administration of rhIL-11 was started with or without the induction of colitis (135 mg/kg TNBS) for 5 days. Motilin and SP levels were measured by RIA, motilin mRNA expression by RT-PCR. TNBS-colitis did not affect plasma motilin levels but increased the motilin content of the duodenal mucosa 1.7-fold. rhIL-11 treatment dose-dependently increased plasma motilin levels (720 microg/kg day: 3.5-fold) and the motilin content of the duodenal mucosa (720 microg/kg day: 3.0-fold). The effects of rhIL-11 were similar in normal rabbits and were accompanied by an increased motilin mRNA expression. TNBS-colitis decreased plasma SP levels 2.7-fold and the SP content in the colonic muscle layer 7.1-fold. The decrease in the muscle layer, but not in the plasma, was normalized by rhIL-11 treatment. In normal rabbits, rhIL-11 caused a decrease in plasma SP levels, but had no effect on the tissue content of SP. In conclusion, treatment of inflamed or normal rabbits with rhIL-11 increases plasma and tissue levels of motilin in the duodenal mucosa via an increased expression of motilin in the endocrine cells and induces the release of SP from extrinsic neurons. These changes do not explain the beneficial effect of rhIL-11 on the lowered contractility in inflamed rabbits although a change in balance of neuropeptides may influence gastro-intestinal inflammation.     

Molecular basis of a high affinity murine interleukin-5 receptor.

The mouse interleukin-5 receptor (mIL-5R) consists of two components one of which, the mIL-5R alpha-chain, binds mIL-5 with low affinity. Recently we demonstrated that monoclonal antibodies (Mabs) recognizing the second mIL-5R beta-chain, immunoprecipitate a p130-140 protein doublet which corresponds to the mIL-3R and the mIL-3R-like protein, the latter chain for which so far no ligand has been identified. In this study we show that a high affinity mIL-5R can be reconstituted on COS1 cells by co-expression of the mIL-5R alpha-chain with the mIL-3R-like protein (beta-chain). Cross-linking of 125I-labeled mIL-5 to the COS1 cells co-transfected with both cDNAs revealed the same pattern as in B13 cells, i.e. two proteins of 60 and 130 kd which correspond to the low affinity mIL-5R alpha-chain and the mIL-3R-like protein, respectively. The dissociation rate of mIL-5 from this reconstituted high affinity site was lower than that of the low affinity site, whereas the association rate was unchanged. Nonetheless, the apparent dissociation constant (Kd) for this reconstituted receptor was still 10-fold higher than the Kd observed for B13 cells. Although the mIL-3R is greater than 90% homologous to the mIL-3R-like protein, no increase in affinity for mIL-5 was detected on COS1 cells co-transfected with the cDNAs for the mIL-5R alpha-chain and the mIL-3R protein.     

Skin tumor responsiveness to interleukin-2 treatment and CD8 Foxp3+ T cell expansion in an immunocompetent mouse model

Recombinant human interleukin-2 (rhIL-2) therapy is approved for treating patients with advanced melanoma yet significant responses are observed in only 10–15% of patients. Interleukin-2 induces Foxp3 expression in activated human CD8 T cells in vitro and expands circulating CD8 Foxp3+ T cells in melanoma patients. Employing IL-2 responsive (B16-F1, B16-BL6, JB/MS, MCA-205) and nonresponsive (JB/RH, B16-F10) subcutaneous tumor mouse models, we evaluated CD8 Foxp3+ T cell distribution and changes in response to rhIL-2 (50,000 U, i.p. or s.q., twice daily for 5 days). In tumor-free mice and subcutaneous tumor-bearing mouse models, CD8 Foxp3+ T cells were a rare but naturally occurring cell subset. Primarily located in skin-draining lymph nodes, CD8 Foxp3+ T cells expressed both activated T cell (CD28⁺, CD44⁺) and Treg (CTLA4⁺, PD1^lo/var, NKG2A^+/var) markers. Following treatment with rhIL-2, a dramatic increase in CD8 Foxp3+ T cell prevalence was observed in the circulation and tumor-draining lymph nodes (TD.LNs) of animals bearing IL-2 nonresponsive tumors, while no significant changes were observed in the circulation and TD.LNs of animals bearing IL-2 responsive tumors. These findings suggest expansion of CD8 Foxp3+ T cell population in response to rhIL-2 treatment may serve as an early marker for tumor responsiveness to immunotherapy in an immune competent model. Additionally, these data may provide insight to predict response in patients with melanoma undergoing rhIL-2 treatment.     

Antitumor effects of human recombinant interleukin-1α and etoposide against human tumor cells: mechanism for synergismin vitro and activityin vivo

Recombinant human interleukin 1α (rh IL-1α) and etoposide (VP-16) synergize for direct growth inhibition of several human tumor cell linesin vitro. Our previous studies demonstrated that VP-16 increased the number of membrane-associated IL-1 receptors (IL-1Rs) and also enhanced the internalization of receptor-bound rh IL-1α. The purposes of this study were to test our hypothess that these events were critical to the synergy between rhIL-1α and VP-16, to determine whether rhIL-1α and VP-16 synergize to increase superoxide (SO) anion radical productionin vitro since SO anion has been implicated in the toxic effects of IL-1, and to investigate the antitumor efficacy of the combinaton against tumors in vivo. A375/C6 melanoma cells and OVCAR-3 ovarian carcinoma cells were tested with IL-1 receptor antagonist (IL-1ra) before exposure to rhIL-1α, VP-16 and rhIL-1α plus VP-16. The synergistic or antagonistic effects were assessed by MTT assay. SO production was measured by reduction of cytochrome C. Athymic female mice bearing the A375/C6 melanoma were treated by rhIL-1α, VP-16, and rhIL-1α+VP-16. The antitumor effects were evaluated by quantitating tumor growth and survival time. Pretreatment with the IL-1ra abrogated the synergistic effects of rhIL-1α and VP-16. The production of SO radical by A375/C6 cells was increased 2.5 fold by the combination of rhIL-1α and VP-16, and the addition of exogenous SOD blocked the synergy between rhIL-1α and VP-16. However, when A375/S0D15 cells which over-expressed manganese superoxide dismutase (MnSOD) after MnSOD cDNA transfecton were exposed to rhIL-1α and VP-16, in vitro antagonism was observed. In vivo studies demonstrated that the combination of rhIL-1α and VP-16 delayed tumor growth better than either agent alone, although long-term survival was not improved because of substantial toxicity. Our results suggest that the synergistic antitumor effects of IL-1α and VP-16 may be due to IL-1R modulation and increased internalization of IL-1-IL-1R complex by VP-16 treatment, as well as to a subsequent increase in SO anion radical production from the tumor cells exposed to both drugs. Thus, the combnation of IL-1α and VP-16 might prove useful for the treatment of malignant diseasein vivo, if the increased toxicity can be reduced or managed. The US Government’s right to retain a non-exclusive royalty-free license on and to any copyright is acknowledged.