Effects of IL-1 on hematopoietic progenitors after myelosuppressive chemoradiotherapy

Recently it has been recognized that IL-1 plays an important role in hematopoietic regulation. Administration of 5-fluorouracil (5-FU) to mice causes prolonged neutropenia. rHIL-1 injected to mice after 5-FU, accelerated the recovery of hematopoietic progenitors and blood neutrophils. The combination of rhIL-1 and rhG-CSF reduced the neutropenic period significantly. Sublethal irradiation of mice induced profound neutropenia for 3 weeks which was associated with 80% mortality. Administration of rhIL-1 20 hours prior to or 2 hours post irradiation resulted in a significantly improved survival and rapid recovery of the neutrophil count. IL-1 administered alone or in combination with other colony stimulating factors to spontaneous breast tumor bearing mice following 5-FU therapy resulted in a rapid recovery of neutrophils, improved survival, and markedly reduced the tumor mass. Experiments in primates demonstrated that rhIL-1 administered to 5-FU treated animals shortened the neutropenic period from 30 to 17 days and increased the number of marrow progenitors responsive to other CSFs. Prolonged administration of IL-1 (14 days) to these animals resulted in a delayed neutrophil recovery as compared to animals receiving short courses of IL-1. rhIL-1 administered to primates receiving marrow grafts after lethal irradiation, did not result in rapid hematopoietic recovery. In humans, studies with CD-34 positive marrow cells showed that IL-1 had a radioprotective effect on a committed and early marrow progenitors. These data show the therapeutic potential of IL-1 in the treatment of chemoradiotherapy induced myelosuppression.     

Chinese herbal formula, Bing De Ling, enhances antitumor effects and ameliorates weight loss induced by 5-fluorouracil in the mouse CT26 tumor model

The use of complementary and alternative medicines-including a variety of herbal therapies-by patients undergoing cancer chemotherapy has been well documented. Despite such widespread use, however, the benefits and potential mechanisms of such herbal medicines remain largely anecdotal. In this study we examined the effects of a Chinese herbal formula, Bing De Ling, when administered as an adjunct to chemotherapeutic agent 5-fluorouracil (5-FU) in the CT26 mouse colon cancer model. 5-FU and Bing De Ling were administered to both nave and CT26 mouse colon cancer-bearing BALB/c mice. Our results indicate that although the herbal formula alone did not result in antitumor effects under experimental conditions, it significantly enhanced 5-FU-induced tumor growth inhibition. Oral administration of Bing De Ling also increased survival rates of both tumor-bearing and tumor-free mice treated with 5-FU. Furthermore, oral administration of Bing De Ling reduced weight loss in tumor-free mice receiving 5-FU when compared to tumor-free mice that received 5-FU alone. Our data further show that 5-FU upregulates serum levels of IL-6, known to contribute to weight loss, in tumor-free mice, and that this increase in IL-6 is significantly less in mice that received Bing De Ling in addition to 5-FU. These data show Bing De Ling both enhances the antitumor responses of 5-FU and ameliorates side effects.     

双歧杆菌脂磷壁酸与5-氟尿嘧啶联用的抗肿瘤研究

目的探讨双歧杆菌脂磷壁酸与5-氟尿嘧啶（5-Fu）联用对H22荷瘤小鼠的抗肿瘤作用及免疫功能的影响。方法双歧杆菌脂磷壁酸单独或联合5-Fu处理H22荷瘤Balb／c小鼠,定期测量肿瘤大小,观察小鼠一般状况;计算抑瘤率、血红细胞数和白细胞数,取脾和胸腺计算脏器指数;HE染色分析肿瘤组织变化;MTT法检测小鼠脾T淋巴细胞增殖转化功能以及ELISA法检测小鼠脾淋巴细胞分泌IFN-γ含量。结果双歧杆菌脂磷壁酸及5-Fu单独应用均可抑制肿瘤生长,但单独5-Fu处理组小鼠一般状况差,毒性反应重;双歧杆菌脂磷壁酸与5-Fu联合应用,与单独5-Fu处理组比较,不仅抑瘤率明显提高（P〈0．01）,且荷瘤小鼠一般状况改善,白细胞数升高,脏器指数增加,小鼠脾T淋巴细胞增殖能力强,脾淋巴细胞分泌IFN-γ,水平提高;光镜观察HE染色瘤体组织,双歧杆菌脂磷壁酸处理组可见大量炎症细胞浸润。结论双歧杆菌脂磷壁酸联合5-FU能增强化疗的抑瘤作用,并能扭转化疗引起的免疫低下现象,起到增效减毒作用。     

Enhanced therapeutic anti-tumor immunity induced by co-administration of 5-fluorouracil and adenovirus expressing CD40 ligand

Bystander immune activation by chemotherapy has recently gained extensive interest and provided support for the clinical use of chemotherapeutic agents in combination with immune enhancers. The CD40 ligand (CD40L; CD154) is a potent regulator of the anti-tumor immune response and recombinant adenovirus (RAd)-mediated CD40L gene therapy has been effective in various cancer models and in man. In this study we have assessed the combined effect of local RAd-CD40L and 5-fluorouracil (5-FU) administration on a syngeneic MB49 mouse bladder tumor model. Whereas MB49 cells implanted into immunocompetent mice responded poorly to RAd-CD40L or 5-FU alone, administration of both agents dramatically decreased tumor growth, increased survival of the mice and induced systemic MB49-specific immunity. This combination treatment was ineffective in athymic nude mice, highlighting an important role for T cell mediated anti-tumor immunity for full efficacy. 5-FU up-regulated the expression of Fas and immunogenic cell death markers in MB49 cells and cytotoxic T lymphocytes from mice receiving RAd-CD40L immunotherapy efficiently lysed 5-FU treated MB49 cells in a Fas ligand-dependent manner. Furthermore, local RAd-CD40L and 5-FU administration induced a shift of myeloid-derived suppressor cell phenotype into a less suppressive population. Collectively, these data suggest that RAd-CD40L gene therapy is a promising adjuvant treatment to 5-FU for the management of bladder cancer.     

G-CSF receptor-binding cyclic peptides designed with artificial amino-acid linkers

Designing small molecules that mimic the receptor-binding local surface structure of large proteins such as cytokines or growth factors is fascinating and challenging. In this study, we designed cyclic peptides that reproduce the receptor-binding loop structures of G-CSF. We found it is important to select a suitable linker to join two or more discontinuous sequences and both termini of the peptide corresponding to the receptor-binding loop. Structural simulations based on the crystallographic structure of KW-2228, a stable and potent analog of human G-CSF, led us to choose 4-aminobenzoic acid (Abz) as a part of the linker. A combination of 4-Abz with beta-alanine or glycine, and disulfide bridges between cysteins or homocysteins, gave a structure suitable for receptor binding. In this structure, the side-chains of several amino acids important for the interactions with the receptor are protruding from one side of the peptide ring. This artificial peptide showed G-CSF antagonistic activity in a cell proliferation assay.     

A novel polysaccharide of black soybean promotes myelopoiesis and reconstitutes bone marrow after 5-flurouracil- and irradiation-induced myelosuppression

The aim of this study was to investigate the promotion of myelopoiesis by an active polysaccharide of black soybean (PSBS). Murine spleen cells were collected from ICR mice and conditioned media (SCM) was prepared by incubating these cells without PSBS (normal-SCM) or with PSBS in concentrations ranging from 12.5 to 100 microg/ml (PSBS-SCM). Murine bone marrow cells were treated with PSBS alone or SCM to induce the formation of colonies, including CFU-GM, CFU-GEMM, BFU-E and HPP-CFC. The concentrations of six hematopoietic growth factors contained in SCM were measured using enzyme-linked immunoassay. In the live animal experiment, PSBS was administered orally to total body-irradiated (TBI) and 5-fluorouracil (5-FU)-treated mice to assess the reconstitution of bone marrow after myelosuppression. PSBS-SCM stimulated CFU-GM, CFU-GEMM, BFU-E and HPP-CFC colony formation with 45.0, 5.0, 6.2 and 6.6-fold increases, respectively. However, neither PSBS alone nor normal-SCM had such a colony-stimulating effect. In PSBS-SCM, the levels of IL-6, IL-17, G-CSF and GM-CSF were markedly increased, but not those of IL-3 and SCF. Oral administration of PSBS in mice not only restored the leukocyte counts reduced by TBI and 5-FU treatment but also enhanced CFU-GM colony formation of bone marrow cells without a significant change in body weight. We conclude that PSBS promotes myelopoiesis activity in the bone marrow, stimulates production of various hematopoietic growth factors from spleen cells, and reconstitutes bone marrow that has been myelosuppressed by irradiation and 5-FU.     

Protective effect of anthocyanin-rich extract from bilberry (Vaccinium myrtillus L.) against myelotoxicity induced by 5-fluorouracil

The toxicities associated with 5-fluorouracil (5-FU), a potent broad-spectrum chemotherapeutic agent, can not only affect the morbidity and the efficacy of chemotherapy but also limit its clinical use. The objective of this study is to investigate the effects of a commercial anthocyanin-rich extract from bilberry (AREB) against 5-FU-induced myelotoxicity in vivo, and against chemosensitivity to 5-FU in vitro. A single injection of 5-FU at 200 mg/kg induced severe peripheral erythrocytopenia, thrombocytopenia and leucopenia as well as hypocellularity of the spleen and bone marrow in C57BL/6 mice. Oral administration of 500 mg/kg of AREB for 10 days significantly increased the number of red blood cells, neutrophils, and monocytes in peripheral blood to 1.2-fold, 9-fold, and 6-fold, respectively, compared with those seen after treatment with 5-FU alone (p< 0.05-0.001). The hypocellularity of the spleen and bone marrow caused by 5-FU was also distinctly alleviated in the AREB-treated group. Furthermore, AREB treatment with 50 and 100 microg/ml as a monomeric anthocyanin did not interfere with, but rather enhanced the chemotherapeutic efficacy of 5-FU in vitro. These results suggest that AREB may have protective potential against 5-FU-induced myelotoxiciy and/or the ability to enhance the chemotherapeutic effectiveness of 5-FU.     

双歧杆菌脂磷壁酸与5-氟尿嘧啶体内联用对肿瘤细胞凋亡的影响

目的研究双歧杆菌脂磷壁酸与5-氟尿嘧啶联用诱导H22荷瘤小鼠肿瘤细胞凋亡的作用机制。方法双歧杆菌脂磷壁酸联合5-FU处理H22荷瘤Balb/c小鼠,计算抑瘤率,观察小鼠生存期;采用Real time-PCR和Western blot方法分别检测荷瘤小鼠肿瘤组织Bcl-2、Bax和Caspase-3 mRNA及蛋白的表达变化。结果双歧杆菌脂磷壁酸联合5-FU应用,与单独5-FU处理组比较,不仅抑瘤率明显提高（P〈0.01）,且荷瘤小鼠存活时间明显延长（P〈0.01）,肿瘤组织Bcl-2表达下降,Bax和Caspase-3表达升高（P〈0.05）。结论双歧杆菌脂磷壁酸联合5-FU可通过上调Bax和Caspase-3,下调Bcl-2,促进肿瘤细胞凋亡,从而发挥协同抗肿瘤作用。     

Combined radiation and enzyme/prodrug treatment for head and neck cancer in an orthotopic animal model.

In an effort to improve the therapeutic outcome for squamous cell cancer of the head and neck, we have used the enzyme cytosine deaminase (CD) and the prodrug 5-fluorocytosine (5-FC) as a means to deliver the chemotherapeutic agent 5-fluorouracil (5-FU) in a tumor-specific manner and have evaluated the use of this treatment in combination with external-beam radiation. Infection of SCCVII cells in culture with a CD-expressing retrovirus and treatment with 5-FC was cytotoxic depending on the time of treatment and dose of 5-FC. An orthotopic model of squamous cell cancer of the head and neck was used in vivo to study the CD/5-FC system both alone and with concurrent radiation due to the radiosensitizing properties that 5-FU generates in situ. Treated mice were imaged using magnetic resonance imaging (MRI), and their survival was evaluated. Neither 5-FU nor radiation either alone or combined provided a survival advantage. In contrast, 5-FC treatment prolonged survival and decreased tumor burden compared to control animals, but the tumors recurred after the treatment ceased. Finally, combined treatment with concurrent administration of 5-FC and radiation resulted in a synergistic decrease in tumor growth and enhanced survival over treatment with 5-FC or radiation alone.     

Augmentation of activities of peripheral granulocytes and of resistance against bacterial infection after administration of G-CSF into mice]

We evaluated the metabolic capability of murine peripheral granulocytes after administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) by quantitative flow cytometric assay for H2O2-dependent oxidative product formation. Intraperitoneal administration of a daily dose of 10 micrograms of rhG-CSF for 5 days induced doubling of the leukocyte population. Differential counting of peripheral leukocytes and scattergram by flow cytometry showed an increased mature granulocyte population. After stimulation with phorbol myristate acetate, the granulocytes of the rhG-CSF-administered mice demonstrated some hyperresponsive population and an increased H2O2 production. The hyperresponsive population showed H2O2 production 4-6 times higher than did normal cells. Granulocytes from the G-CSF-treated mice revealed an augmented phagocytic activity and an increased expression of Mac-1 molecules. Moreover, mice treated with G-CSF showed an enhanced resistance against intravenous infection with a lethal dose of E. coli. Granulocytes showing such markedly increased oxidative metabolism may be a significant component of the host defence to various infective organisms.     

Sensitization to radiation from an implanted 125I source by sustained intratumoral release of chemotherapeutic drugs

We have investigated tumor response to low-dose-rate irradiation from an implanted 125I source alone or in conjunction with intratumoral drug administration. The drug (cis-DDP or 5-FU) was incorporated homogeneously into the co-polymer CPP-SA, 20:80, and the polymer/drug rods were implanted in the RIF-1 fibrosarcomas growing subcutaneously in C3H mice. Twenty-four hours later, the tumor was implanted with an 125I seed. Tumor growth time was the end point in these experiments. For implanted 125I sources of different dose rates and implant times giving a range of total doses, a consistent dose-response relationship was shown between tumor growth time and total dose. In other experiments, 125I sources of different specific activities were implanted for periods of time adjusted so that the total dose to the tumor was always the same. When the 125I implant was combined with 5-FU, greater than additive responses were seen for both short (30 h) and long (96 h) 125I treatment times. In contrast, a short-duration (30 h) 125I implant combined with cis-DDP was the least effective treatment, giving a combined response that was no better than additive, whereas 96 h exposure to 125I combined with cis-DDP was the most effective combined treatment. It is conjectured that this inverse dose-rate effect seen when cis-DDP is combined with low-dose rate radiation is related to a cell cycle effect and/or to inhibition of repair of radiation damage by cis-DDP.     

HAPO促进放射损伤小鼠的造血重建

目的 明确人促血液血管细胞生成素 (HAPO)对骨髓抑制小鼠的造血重建作用。方法 研究HAPO、G-CSF对骨髓抑制小鼠的促造血作用,以700 cGy 137Csγ射线全身照射的Balb/c小鼠为模型,观察照射后小鼠的生存率;检查血常规;计数内源性脾结节;计数骨髓细胞数;采用半固体培养基进行集落培养检测骨髓细胞的高增殖潜能;取小鼠骨髓细胞接种于96孔培养板,分别在照射前或照射后加HAPO、G-CSF培养72hr,MTT方法测定活细胞数;取小鼠骨髓细胞,分别在照射后加HAPO,培养3周后观察各组小鼠骨髓细胞的生长情况。结果 HAPO、G-CSF均可明显提高放射后的小鼠的生存率;使内源性的脾集落增加。照射后的各组小鼠外周血白细胞变化较为明显,HAPO组白细胞恢复快于PBS组,也可高于G-CSF组。各组小鼠骨髓细胞数虽然14天时G-CSF组最为明显,但32天时HAPO组骨髓细胞数超过G-CSF组,至42天时基本恢复正常;而G-CSF组在32天、42天时骨髓细胞数仍低于正常值。在7天、14天、32天时取各组小鼠骨髓细胞高增殖潜能检测试验,HAPO组生成的GEMM-CFU数均最多。在照射前与HAPO、G-CSF孵育的骨髓细胞,HAPO组活细胞数量比对照组明显增高,而G-CSF组与对照组无明显差异。骨髓细胞被照射后培养72hr时,MTT测定显示不同剂量HAPO、G-CSF均能促进放射后骨髓细胞的增殖。骨髓细胞被照射后继续培养3周,HAPO组均有造血岛生成,细胞sca-1、CD31呈阳性,周围CD31阳性的内皮细胞增多。而PBS组则未出现造血岛,基质细胞中极少有CD31阳性细胞的内皮细胞,未发现sca-1阳性细胞。结论 体内、外实验表明,人促血液血管细胞生成素HAPO对放射损伤的Balb/c小鼠有明显的促造血重建作用,提高小鼠的生存率,促进其造血干细胞的增殖与生长。     

The Combination of a Low-Dose Chemotherapeutic Agent, 5-Fluorouracil,and an Adenoviral Tumor Vaccine Has a Synergistic Benefit on Survival in a Tumor Model System

Standard cancer therapies, particularly those involving chemotherapy, are in need of modifications that both reduce short-term and long-term side effects as well as improve the overall survival of cancer patients. Here we show that combining low-dose chemotherapy with a therapeutic vaccination using an adenovirus encoding a model tumor-associated antigen, ovalbumin (Ad5-OVA), had a synergistic impact on survival in tumor-challenged mice. Mice that received the combinatorial treatment of Ad5-OVA plus low-dose 5-fluorouracil (5-FU) had a 95% survival rate compared to 7% and 30% survival rates for Ad5-OVA alone and 5-FU alone respectively. The presence of 5-FU enhanced the levels of OVA-specific CD8⁺ T lymphocytes in the spleens and draining lymph nodes of Ad5-OVA-treated mice, a phenomenon that was dependent on the mice having been tumor-challenged. Thus 5-FU may have enhanced survival of Ad5-OVA-treated mice by enhancing the tumor-specific immune response combined with eliminating tumor bulk. We also investigated the possibility that the observed therapeutic benefit may have been derived from the capacity of 5-FU to deplete MDSC populations. The findings presented here promote the concept of combining adenoviral cancer vaccines with low-dose chemotherapy.     

Gas Chromatographic Determination of a New Fungicide,Procymidone (Sumilex®) in Technical Preparation and Formulation

Monoclonal antibodies (MoAbs) reacting with human G-CSF and /or its muteins were established by cell fusion between P3.X63/Ag8.U1 myeloma cells and spleen cells from BALB/C mice immunized with recombinant human intact G-CSF or its mutein, designated ND28. Two MoAbs reacted with intact G-CSF and all kinds of muteins tested, designated KM341 and KM342, and two MoAbs specific for intact G-CSF, designated KM340 and KM343, were obtained from the mice immunized with recombinant human intact G-CSF.

The sera from the mice immunized with a mutein of G-CSF, ND28, reacted with intact G-CSF and all muteins tested. Two MoAbs specific for ND28, designated KM498 and KM511, were obtained from these mice. These MoAbs seem to recognize the sequence of a few amino acids that is peculiar for ND28. However, the epitopes recognized by KM498 and KM511 were maybe subtly different, because KM498 and KM511 could not completely inhibit each other.

Human G-CSF and/or its muteins could be measured by sandwich ELISA using these MoAbs with suitable combinations. The immuno-affinity column using KM342 or KM498 adsorbed G-CSFs or specifically ND28, previously. By elution with 0.15m NH₄OH, the G-CSFs or ND28 were eluted with a high recovery.     

Effect of a glucan,sizofiran, on natural-killer activity of 5-fluorouracil-treated murine bone marrow cells

Summary The number of bone marrow cells in C3H/He mice was reduced 3–4 days after treatment with 130 mg/kg intraperitoneal 5-fluorouracil (5-FU). Higher rates of spontaneous proliferation and natural killer (NK) activity, accompanied by an increase in asialoGM1-positive cells, were observed in treated mice. When sizofiran at a dose of 200 µg/animal was intramuscularly injected after 5-FU treatment, the rates of proliferation and NK activity of bone marrow cells were higher than with 5-FU alone. The cell number was not influenced by sizofiran alone. These results indicate that all precursors of the various mature cell types (including NK cells) differentiate and regenerate rapidly to replace cells damaged by 5-FU treatment, and that sizofiran has the potential to assist this recovery. These results suggest that administration of sizofiran after chemotherapy may be useful in cancer patients.     

Resveratrol synergistically augments anti-tumor effect of 5-FU in?vitro and in?vivo by increasing S-phase arrest and tumor apoptosis

Many studies have shown that natural dietary agents, in combination with chemical agents, can improve the therapeutic response of cancers to chemotherapy and reduce the associated side-effects. In the present study, we investigated the therapeutic potential and mechanisms of anticancer effects for the combination of 5-fluorouracil (5-FU) and resveratrol (Res). In these studies, we employed the cancer cell lines TE-1 and A431 and an animal model of skin cancer. The presented results provide the first evidence that Res can enhance the anti-tumor potency of 5-FU by inducing S-phase arrest. The combination of Res and 5-FU demonstrates synergistic efficacy, causing tumor regression in a two-stage model of mouse skin carcinogenesis induced by DMBA and TPA. There was clear evidence of Res augmenting the growth inhibitory effect of 5-FU on the TE-1 and A431 cancer cells in vitro. In the in vivo studies, the tumor regression rate in the combination group increased significantly after four weeks of treatment (P < 0.01). The combination of 5-FU and Res significantly increased the percentage of apoptotic cells and the level of activated caspase-3, cleaved PARP and p53 proteins as well as increased the Bax/Bcl-2 ratio. In conclusion, the 5-FU/Res combination enabled a more effective inhibition of cell growth and the induction of apoptosis in cancer cells than 5-FU alone. The results of this study suggest that chemotherapy using natural dietary agents with chemical agents represents a superior cancer treatment option.     

THF-γ2, a thymic hormone,increases immunocompetence and survival in 5-fluorouracil-treated mice bearing MOPC-315 plasmacytoma

Summary The effect of the thymic hormone, THF-2, on the immunocompetence of 5-fluorouracil (5-FU)-treated BALB/c mice, bearing MOPC-315 tumor, was examined. Treatment of noninoculated or tumor-bearing mice with THF-2 after 5-FU injection, resulted in an increase in the antibody response to sheep red blood cells and in the allogeneic response in spleen cell cultures and had no effect on the concanavalin-A-induced interleukin-2 secretion beyond that caused by 5-FU alone. Treatment with either 5-FU alone or 5-FU and THF-2 resulted in restoration to normal values of Lytl- and L3T4-positive populations in tumor-bearing mice. THF-2 prolonged the survival time of mice bearing MOPC-315 tumor beyond that observed in mice treated with 5-FU alone.     

Prevention of 5-fluorouracil-induced infection with indigenous Escherichia coli in tumor-bearing mice by nonspecific immunostimulation.

We have previously reported that the lethal toxicity of 5-fluorouracil (5-FU) in specific-pathogen-free mice is due to an indigenous infection with Escherichia coli (K. Nomoto, T. Yokokura, Y. Yoshikai, et al. Can. J. Microbiol. 37:244-247, 1991). In the present study, we demonstrate that nonspecific immunostimulation augments host resistance against the lethal toxicity of 5-FU in tumor-bearing mice. Intravenous administration of a preparation of heat-killed Lactobacillus casei (LC 9018), a nonspecific immunostimulant, at a dose of 20 mg/kg to BALB/c mice augmented their resistance against the lethal toxicity of 5-FU if the preparation was injected into the mice 10-40 days before administration of 5-FU. Injection of LC 9018 into BALB/c mice bearing Meth A fibrosarcoma also enhanced their resistance against the lethality of 5-FU. Systemic infection with E. coli was induced in all of the 5-FU-treated tumor-bearing mice 10 days or more after administration of the drug at a lethal dose of 500 mg/kg, and it was accompanied by an overgrowth of the bacteria in the intestine. Treatment of tumor-bearing mice with LC 9018 resulted in decreased rates of occurrence of systemic infection with E. coli and inhibition of overgrowth of the bacteria in the intestine after administration of 5-FU. A single administration of either LC 9018 or 5-FU significantly inhibited the growth of Meth A cells in vivo, and a combined antitumor effect was shown in the mice treated with both 5-FU and LC 9018.     

Anti-hepatoma activity in mice of a polysaccharide from the rhizome of Anemone raddeana

A neutral polysaccharide fraction (ARP) prepared from the rhizome of Anemone raddeana was tested for its anticancer activity in H22 tumor-bearing mice by oral administration. ARP could not only significantly inhibit the growth of H22 transplantable tumor, but also remarkably promote splenocytes proliferation, NK cell and CTL activity, as well as serum IL-2 and TNF-α production in tumor-bearing mice. In addition, ARP treatment to tumor bearing mice had no toxicity to body weight, the liver and kidney. Moreover it could reverse the hematological parameters induced by 5-fluorouracil (5-FU) to near normal. The above results suggested that the antitumor activity of ARP might be achieved by improving immune response, and they could act as antitumor agent with immunomodulatory activity.     

Thymosin α1 restores NK-cell activity and prevents tumor progression in mice immunosuppressed by cytostatics or X-rays

The effect of thymosin against tumor progression was examined in mice immunosuppressed by cytostatics or X-ray irradiation. When pretreated with cytostatic agents, such as 5-fluorouracil (5-FU) or BCNU, or by X-ray, and then inoculated with P388 or L1210 leukemias, mice died rapidly within a few days. In these systems, thymosin alpha 1 given concomitantly with the cytostatic agents or after X-irradiation prevented rapid death and extended survival, although the mice eventually died with leukemia like normal mice inoculated with cells of the same tumor. Rapid death in the 5-FU-treated mice was also prevented by adoptive transfer of spleen cells from the donor mice if these had been treated with 5-FU plus thymosin alpha 1, but not if they had received 5-FU alone. However, the restorative activity of the donor spleen cells was abrogated by treatment with anti-asialo GM1, but not by treatment with anti-Thy 1 or anti-mouse Ig serum, suggesting that the effector cells in the spleen are NK cells. In fact, thymosin alpha 1, when given concomitantly with 5-FU or after X-irradiation, maintained the NK activity of spleen, which was damaged by treatment with 5-FU or X-irradiation alone. The present study indicates that thymosin alpha 1 exerts a preventive activity against progression of leukemias at least in part through an effect on NK cells or their progenitor cells.