Chronic dietary fat intake modifies the postprandial response of hemostatic markers to a single fatty test meal

BACKGROUND: Hemostasis is the result of a complex equilibrium between coagulation and fibrinolysis, and the influence of different dietary models on this equilibrium is not entirely known. OBJECTIVE: The objective was to compare the effects of the chronic intake of different dietary models on postprandial hemostasis. DESIGN: In a randomized crossover design, 20 healthy men consumed for 28 d each diets rich in monounsaturated fatty acids (MUFAs), saturated fatty acids (SFAs), and carbohydrates plus n-3 fatty acids (CHO/N3). Fasting and postprandial hemostatic factors (factor VII coagulant activity, plasminogen activator inhibitor-1, tissue-type plasminogen activator, d-dimer, and thromboxane B(2)) were measured; meal tests for the postprandial measures were based on butter, virgin olive oil, and walnuts for the SFA, MUFA, and CHO/N3 diets, respectively. RESULTS: There were no differences in the fasting variables after the dietary periods. After the 3 fatty meals were consumed, we observed an increase in thromboxane B(2) and d-dimer and a reduction in tissue plasminogen activator, irrespective of the dietary model. The MUFA or CHO/N3 meals lowered postprandial concentrations of factor VII coagulant activity, although the reduction was greater after the MUFA-enriched meal. The concentration of plasminogen activator inhibitor-1 was greater after the SFA meal than after the other 2 meals. CONCLUSIONS: The administration of a fatty meal induces a postprandial procoagulant tendency, irrespective of the type of fat consumed. However, the use of a dietary model rich in SFA creates a more procoagulant environment than does a model that includes MUFA or CHO/N3 as the source of fatty acids.     

Effect of toxaphene on isolated hepatocytes of the yellowtail flounder, Pleuronectes ferrugineus storer

The histochemical and enzyme cytochemical effects of Toxaphene were investigated using isolated hepatocytes in suspension culture from laboratory-bred juvenile, female yellowtail flounder (Pleuronectes ferrugineus). Hepatocytes were kept in suspension culture for 4 days and exposed for 3 days to a control medium, to a medium with hexane (the solvent of Toxaphene), or to a medium with Toxaphene in two different concentrations (1 and 10 mocrog/ml). Subsequently, the cultivated cells were examined histochemically (Sudan black B, oil red O, Schmorl's reaction) and enzyme cytochemically (acid phosphatase, NADPH-ferrohemoprotein reductase). Toxaphene decreased the viability of the isolated cells significantly, as compared to the control suspensions. Toxaphene also increased the storage of total and neutral lipids (as demonstrated by Sudan black B and oil red O, respectively) in a dose-dependent manner. In addition, Toxaphene increased the enzymatic activity of acid phosphatase, and increased the storage of lipofuscin pigment (as demonstrated by the Schmorl's reaction) within the hepatocytes, suggesting an increase in the number and/or size of the lysosomes. Hexane did not have a significant toxic effect on the isolated hepatocytes. It is concluded that Toxaphene is potentially toxic to fish in a marine environment and that this in vitro system may provide a model for assessing the direct effect of various toxicants on fish hepatocytes.     

Induction of innate immunity by nasal influenza vaccine administered in combination with an adjuvant (cholera toxin)

Inactivated influenza vaccine was administered intranasally to BALB/c mice together with an adjuvant (cholera toxin B subunit [CTB] supplemented with a trace amount of the whole toxin, CTB*) and its ability to induce innate immunity and confer protection against influenza was examined. Nasal wash virus titres 3 days after inoculation of homologous viruses were measured as an index of the ability of the vaccine to confer protection in mice immunized with either CTB*-combined vaccine or CTB* alone 1-21 days previously. The results were as follows. (1) Partial but significant reduction of the nasal-wash virus titres (prevention) was detected beginning 3 days after the vaccination, that is, 2 days earlier than the appearance of both virus-specific antibody-forming cells (AFCs) in the nasal-associated lymphoid tissue (NALT) and virus-specific IgA antibody responses in the nasal washes of mice immunized with the CTB*-combined vaccine. (2) The protection, detected on day 3 and peaking on day 5 but lost by day 21, was also conferred in mice immunized with CTB* alone. (3) The non-specific prevention was detected at doses of more than 0.3 microg of CTB*/mouse. (4) The nonspecific protection beginning 3 days after the immunization involved the enhanced expression of cytokine mRNAs (IL-15 and IL-18), considered responsible for natural killer (NK) cell activation, by the non-T cell populations in the NALT. (5) Normal NALT cells, when cultured in vitro with CTB*, secreted IL-1beta within a few hours in culture. These results demonstrate that the CTB*-combined vaccine, when given intranasally into mice, can confer nonspecific protection against influenza beginning 3 days after the vaccination and that CTB* also possessed this ability to confer protection non-specifically and temporarily by inducing the secretion of IL-1beta, one of the most important cytokines that initiates both innate and adaptive immunity, and also NK cell activity.     

Proliferation and differentiation of stromal-vascular cells in primary culture differ between neonatal pigs consuming maternal or formula milk

Proliferation and differentiation of preadipocytes from 7-d-old pigs consuming maternal or formula milk were examined in primary culture of stromal-vascular (s-v) cells derived from subcutaneous adipose tissue. Unsuckled pigs were bottle-fed isoenergetically with colostrum and then sow's milk (SM) or with formula milk alone (F) from birth to 7 d. Isolated cells were exposed to serum-supplemented medium and serum-free medium to determine proliferation and differentiation, respectively. Proliferation estimated between d 3 and 4 of culture was higher (P<0.05) in cells from F than SM pigs. In addition, the number of s-v cells isolated from 1 g of adipose tissue was higher (P<0.01) in F than SM pigs. Variables assessing differentiation were also affected. The percentage of differentiating cells and lipoprotein lipase (LPL) activity were lower (P<0.05) in F than SM pigs, whereas malic enzyme (ME) activity did not differ significantly between the two groups. In conclusion, formula milk increased the number of s-v cells and their capacity for proliferation, whereas the potential for cell differentiation was lower compared with cells from the maternal milk group. Further studies are required to identify the growth and/or nutritional factors that are implicated in the observed differences and to determine whether subsequent development of adipose tissue is affected.     

TPA基因克隆与体外表达模型建立

目的 重组TPA基因并构建体外表达模型，为缺血性心脏疾病的基因治疗及防止血管再狭窄奠定基础。方法 构建真核表达载体pcDNA3．1( )TPA，然后将pcDNA3．1( )TPA转入中国苍鼠卵巢(CHO)细胞，并观察外源性TPA表达情况。结果 真核表达载体pcDNA3．1( )TPA在CHO细胞表达量好，发色底物法测得外源性TPA活性为12．296IU／10^6细胞／24hr，未转pcDNA3．1( )TPA的CHO细胞测得为3．176IU／10^6细胞／24hr；酶联免疫实验(ELASA)检测结果为586．172ng／10^6细胞／24hr，未转pcDNA3．1( )TPA的CHO细胞测得为9．608ng／10^6细胞／24hr，达未转TPA基因组的60倍。结论 pcDNA3．1( )TPA转入CHO细胞后，外源性TPA基因获有效表达，为TPA临床基因治疗提供了理论依据。     

Combined marginal folate and riboflavin status affect homocysteine methylation in cultured immortalized lymphocytes from persons homozygous for the MTHFR C677T mutation

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, the methyl donor for the synthesis of methionine from homocysteine. A common C677T mutation in the MTHFR gene renders the enzyme approximately 50% less active than the wild-type enzyme as shown in in vitro studies using cell extracts. We developed an immortalized cell culture model to determine whether the lower in vitro activity imparted by the homozygous (T/T) genotype is demonstrated in situ when exposed to adequate and marginal physiologic concentrations of folate and riboflavin. T/T MTHFR activity was compared with that of C/C genotype cell extracts by an in vitro assay and in intact cells by measuring the distribution of folate forms, the accumulation of homocysteine in the medium and the synthesis of methionine from formate and homocysteine. Under adequate nutrient conditions, the in vitro activity of the T/T MTHFR enzyme was approximately half that of the C/C genotype. Similarly, the proportion of 5-methyltetrahydrofolate in cells with the T/T genotype was approximately half that of the cells with wild-type MTHFR. In contrast, homocysteine accumulation in the culture medium was low and not different between genotypes, nor was there a difference in methionine synthetic capacity. Significant differences were observed between genotypes only when the supply of both folate and riboflavin was limited in the medium, which resulted in increased homocysteine accumulation and decreased methionine production in the T/T genotype. These data are consistent with the current understanding of the molecular interaction of the MTHFR mutant with folate substrates and the FAD prosthetic group.     

Effect of plasmin, plasminogen activators and a plasmin inhibitor on bovine in vitro embryo production

In the present study, four experiments were conducted to investigate the possible effects of plasminogen activators (urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator (t-PA)), plasmin, and a plasmin inhibitor (epsilon-aminocaproic acid (epsilon-ACA)) on different stages of bovine in vitro embryo production (IVP). The concentrations of these modifiers in IVP media were conditioned according to the plasminogen activator activity of bovine preovulatory follicular fluid. Media were modified in a single phase of IVP with an 18 h or 24 h incubation for in vitro maturation (IVM) and a 24 h or 48 h incubation for the IVF or in vitro culture (IVC), respectively. After IVM the oocytes were either fixed and stained or underwent IVF and IVC. The main findings were: (1) plasmin added to the 18 h IVM medium increased maturation rate without affecting fertilisation or embryo development rates; (2) t-PA added to the IVF medium significantly increased cleavage; (3) u-PA added to the IVC medium significantly increased embryo development rates; (4) the efficiency of all phases of IVP was reduced after the addition of epsilon-ACA; and (5) plasminogen addition had no effect in any IVP phase tested. We conclude that the members of the plasminogen activator-plasmin system contribute in different ways to bovine IVM, IVF and IVC.     

Mouse foot-pad inoculation as an aid to the isolation of Leishmania spp. from patients

Portions of splenic or subcutaneous saline aspirates from suspected visceral or cutaneous leishmaniasis patients were inoculated into NNN media with an overlay of Schneider's medium or Schneider's medium alone for routine parasitological diagnosis. The remaining portions of the aspirates were used for preparing Giemsa-stained smears and for subcutaneous inoculation into hind foot-pads of Balb/c mice. Saline aspirates obtained from the foot-pads 2-14 d after inoculation were inoculated into Schneider's medium and examined for promastigotes. Parasite isolation was achieved from 90% of confirmed leishmaniasis patients by either culture method alone. Mouse foot-pad aspiration demonstrated parasites in 95% of all patients, and in over 80% of the confirmed cases of leishmaniasis. Combined culturing and aspirate smear examination was more efficient than foot-pad inoculation alone for the demonstration of leishmanial infection. Foot-pad aspiration does not entail killing animals and was sensitive for parasite isolation; it may be a useful short-term adjunct to existing parasite isolation methods, especially under field conditions where the risks of culture contamination may be high.     

大鼠骨髓间充质干细胞体外生长增殖特点的实验研究

目的 了解应用全骨髓贴壁法分离的大鼠骨髓间充质干细胞(bone mesenchymal stem cells,BMSCs)的生长、增殖特点,以及接种密度、培养时间对细胞增殖的影响,为预防和治疗机体退行性疾病等提供多潜能的种子细胞.方法 通过全骨髓贴壁法分离SD大鼠BMSCs,在体外条件下培养,应用倒置显微镜观察细胞形态学特征及流式细胞仪鉴定、检测大鼠BMSCs表面标志抗原,并通过分析对接种于96孔板不同接种密度(2×103、5×103、1×104个细胞/ml)连续培养10 d细胞生长曲线的特点,研究接种密度和培养时间对BMSCs生长、增殖的影响.结果 流式细胞仪分析CD29细胞阳性率为97.68%(7607/7788),CD34、CD45细胞阳性率分别为7.93%(661/8340)、2.76%(215/7788),符合BMSCs表面标记物表达特征.通过换液及消化传代,3代以上的BMSCs较为均一纯化,呈典型的旋涡或放射状生长,约传代至7～10代时出现细胞衰老并衰老细胞逐渐增多;中等密度(5×103个细胞/ml)接种细胞的生长曲线呈较典型的S形曲线.第1、2天为潜伏期;第3～5天为对数生长期;第6天细胞数目进入平台期;第8～10天细胞数量稍有下降.结论 全骨髓贴壁法是获得BMSCs较为简便有效的方法,且中等量接种密度更有利于细胞增殖,可获得更多的种子细胞.     

Influence of intron and exon splicing enhancers on mammalian cell expression of a truncated spike protein of SARS-CoV and its implication for subunit vaccine development

The spike (S) protein of severe acute respiratory syndrome coronavirus (SARS-CoV) is important for vaccine development. A truncated S protein of the TW1 strain, STR2 (88 kDa), carrying three S fragments (S74-253, S294-739, and S1129-1255) was investigated to study the influences of intron and exon splicing enhancers to improve STR2 protein expression in mammalian cells. Our results showed that STR2 protein expression with the use of an 138 base-pair intron addition increased by 1.9-, 2.5-, and 4.1-fold in Vero E6, QBI-293A cells, and CHO/dhFr- cells (dihydrofolate reductase [dhfr] gene deficient CHO cells), respectively. Using the exon splicing enhancers, including a bidirectional splicing enhancer (BSE) or an exon splicing enhancer derived from the EDA alternative exon of the fibronectin gene (EDA ESE), were also found to increase STR2 protein expression in CHO/dhFr- cells by 1.7- and 2.6-fold. Nevertheless, combination of the intron and the exon splicing enhancers resulted in suppressing the intron-enhancing e STR2 protein expression in in CHO/dhFr- cells. Our studies also demonstrated the STR2 protein was mainly as the Endo H-sensitive glycoprotein (115 kDa) expressed in Vero E6, QBI-293A, and CHO/dhFr- cells. However, only a minor form of the Endo H-resistant glycoproteins ( approximately 130 kDa) was detected in CHO/dhFr- cells. Taken together, our results indicated that intron had a better enhancing effect on STR2 protein expression than exon splicing enhancers, and the expression of approximately 130 kDa STR2 glycoprotein was enhanced by the intron addition into the expression vector construct. Results of the present study can provide an optimal strategy to enhance SARS-CoV S protein expression in mammalian cells and may contribute to the development of SARS-CoV subunit vaccine.     

Antitumor activity of astaxanthin and its mode of action

Astaxanthin, a carotenoid without vitamin A activity, may exert antitumor activity through the enhancement of immune responses. Here, we determined the effects of dietary astaxanthin on tumor growth and tumor immunity against transplantable methylcholanthrene-induced fibrosarcoma (Meth-A tumor) cells. These tumor cells express a tumor antigen that induces T cell-mediated immune responses in syngenic mice. BALB/c mice were fed astaxanthin (0.02%, 40 micrograms/kg body wt/day in a beadlet form) mixed in a chemically defined diet starting zero, one, and three weeks before subcutaneous inoculation with tumor cells (3 x 10(5) cells, 2 times the minimal tumorigenic dose). Three weeks after inoculation, tumor size and weight were determined. We also determined cytotoxic T lymphocyte (CTL) activity and interferon-gamma (IFN-gamma) production by tumor-draining lymph node (TDLN) and spleen cells by restimulating cells with Meth-A tumor cells in culture. The astaxanthin-fed mice had significantly lower tumor size and weight than controls when supplementation was started one and three weeks before tumor inoculation. This antitumor activity was paralleled with higher CTL activity and IFN-gamma production by TDLN and spleen cells in the astaxanthin-fed mice. CTL activity by TDLN cells was highest in mice fed astaxanthin for three weeks before inoculation. When the astaxanthin-supplemented diet was started at the same time as tumor inoculation, none of these parameters were altered by dietary astaxanthin, except IFN-gamma production by spleen cells. Total serum astaxanthin concentrations were approximately 1.2 mumol/l when mice were fed astaxanthin (0.02%) for four weeks and appeared to increase in correlation with the length of astaxanthin supplementation. Our results indicate that dietary astaxanthin suppressed Meth-A tumor cell growth and stimulated immunity against Meth-A tumor antigen.     

Occurrence of both urokinase and tissue plasminogen activator in the human endometrium

The presence of two different plasminogen activators, urokinase and tissue activator, in the endometrium was demonstrated immunologically. Tissue activator was prevalent and urokinase was present in only minor amounts in endometrial tissue extractions.In tissue culture, on the contrary, endometrial explants released more urokinase than tissue activator into the medium and the fibrinolytic activity of the medium was mainly due to urokinase. This may reflect different modes of intracellular storage of the two activators, or the presence of a pre-urokinase which is immunologically different from urokinase and which is activated upon release.The amount of urokinase and fibrinolytic activity released into the culture medium was higher when endometrium samples had been obtained in the midcycle phase than in the proliferative and luteal phases. This pattern mimics the $\text{in vivo}$ release of plasminogen activator from the endometrium into the uterine fluid.Endometrium obtained from IUD-users had a higher content of urokinase than that obtained from non-users.     

HBV阳性血清体外感染HepG-2细胞方法建立

目的建立乙型肝炎病毒(HBV)阳性血清体外感染人肝癌细胞系HepG-2的方法。方法低温同步化处理HepG-2细胞后用高浓度HBV阳性血清与含有4%聚乙二醇的无血清伊格尔极限必需培养基(MEM)共孵育HepG-2细胞,设阴性对照组和空白对照组;18 h后加入含10%胎牛血清的MEM继续培养6 d,每隔24 h收集细胞和培养上清,荧光定量PCR检测HBV DNA,间接免疫荧光技术检测细胞内乙型肝炎病毒表面抗原(HBsAg)。结果 HBV阳性血清感染组HepG-2细胞内和培养上清中在感染后第1 d可检测到HBV DNA,分别为(16.04±7.99)×103、(8.84±3.97)×103 copies/mL,细胞内DNA含量在第2 d达到(3.51±1.86)×105 copies/mL,然后逐渐下降,在第4 d降到检测下限以下,而培养上清中病毒DNA在检测的时间内逐渐升高,在第6天达到(8.41±5.34)×105 cop-ies/mL;间接免疫荧光检测感染组细胞膜和胞浆中均有HBsAg表达;传代培养感染细胞后,在第1代细胞培养上清和细胞内均可检测到HBV DNA(3.58×105、7.34×105 copies/mL),第2代培养上清中可检测到少量HBV DNA(2.89×103 copies/mL),但细胞内检测到HBV DNA低于检测下限(896 copies/mL),第3代细胞的上清和细胞内均未检测到HBV DNA。结论 HBV阳性血清在一定条件下可以感染HepG-2细胞,病毒能在细胞内进行短期复制。     

Construction and preclinical evaluation of mmCT,a novel mutant cholera toxin adjuvant that can be efficiently produced in genetically manipulated Vibrio cholerae

There is an urgent need for new adjuvants that are effective with mucosally administered vaccines. Cholera toxin (CT) is the most powerful known mucosal adjuvant but is much too toxic for human use. In an effort to develop a useful mucosal adjuvant we have generated a novel non-toxic mutant CT molecule that retains much of the adjuvant activity of native CT. This was achieved by making the enzymatically active A subunit (CTA) recalcitrant to the site-specific proteolytic cleavage (“nicking”) required for toxicity, which was found to require mutations not only in the two residues rendering the molecule resistant to trypsin but also in neighboring sites protecting against cleavage by Vibrio cholerae proteases. This multiple-mutated CT (mmCT) adjuvant protein could be efficiently produced in and purified from the extracellular medium of CT-deleted V. cholerae. The mmCT completely lacked detectable enterotoxicity in an infant mouse model and had >1000-fold reduced cAMP inducing activity compared to native CT in a sensitive mammalian target cell system. It nonetheless proved to have potent adjuvant activity on mucosal and systemic antibody as well as cellular immune responses to mucosally co-administered antigens including oral cholera and intranasal influenza vaccines. We conclude that mmCT is an attractive novel non-toxic mucosal adjuvant for enhancing immune responses to co-administered mucosal vaccines.     

三种细胞培养模型的效果评价

原代大鼠肝细胞经不同体外细胞培养模型培养后 ,对肝细胞的酶渗出量、白蛋白分泌水平和细胞色素P450 1A(CYP 1A)活性进行了分析。结果显示 :在三种培养模型中 ,培养液的LDH水平随培养时间的延长而逐渐降低 ,但在单层培养 (MC)的第 5天 ,LDH水平明显升高 ,而夹层培养 (SC)的LDH在第 8天后没有检出 ,AST和ALT水平在整个培养过程中无明显变化。在生物反应器中 (bioreactor) ,肝细胞基础CYP1A活性可维持 2周以上 ,培养液中白蛋白的含量以生物反应器最高 ,其次是SC和MC。随着培养时间的延长 ,MC和SC中肝细胞CYP 1A活性逐渐降低 ,且MC肝细胞CYP 1A活性的下降速度比SC快。这种现象可被细胞色素P450 (P450 )的诱导剂如奥美拉唑和 3 甲基胆蒽 (3 MC)部分改变 ,MC肝细胞的诱导作用总是比SC肝细胞强。结果证实每一个体外细胞培养模型都有各自的优缺点 ,不同的体外细胞培养模型可以解决问题的不同方面     

Cytotoxicity of oxidation derivatives of cholesterol on cultured aortic smooth muscle cells and their effect on cholesterol biosynthesis.

Aortic smooth muscle cell death is an important initial lesion of atherosclerosis. A number of autooxidation products of cholesterol which has been recognized recently has the capability of inducing rabbits' aortic smooth cell death in vitro. Twelve oxidation derivatives of cholesterol, available commercially, were dissolved in small amounts of ethanol, then added to the culture medium at levels not exceeding 0.8%. The medium contained 10% fetal calf's serum which served as an in situ vehicle for the sterols. The degrees of cytotoxicity were graded and measured as percentage of dying and dead cells in the cultures within 24 hr. 25-Hydroxycholesterol and cholesthan-3 beta, 5 alpha, 6 beta-triol, were the most toxic compounds among the sterols tested. When these oxidation derivatives of cholesterol were added to these cultured cells, they significantly depressed activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase, a regulatory enzyme of cholesterol biosynthesis (up to 83% inhibition by 25 hydroxycholesterol at a 3 microgram/ml concentration in culture medium) but the sequence of degree of inhibition was not exactly correlated with that of cytotoxicity. Various mechanisms are speculated. Purified cholesterol showed no cytotoxic effect and minimal inhibition of cholesterol biosynthesis.     

体外培养的角膜缘上皮细胞生物学特性

目的　观察体外培养的角膜缘上皮细胞生物学特性。方法　体外组织块培养兔角膜缘上皮细胞，倒置显微镜观察活细胞生长情况，透射电镜观察其超微结构，用流式细胞仪检测细胞的增殖能力，使用MTT方法绘制传代细胞的生长曲线。结果 角膜缘组织块培养第6d培养的角膜缘上皮细胞形成单层，培养的细胞具有代谢旺盛和较高的增殖能力，传代的角膜缘上皮细胞在第4d达生长高峰。结论 体外培养的第1、2代角膜缘上皮细胞既保持角膜上皮特性，又县有强的增殖能力。     

Incorporation of CpG oligodeoxynucleotide fails to enhance the protective efficacy of a subunit vaccine against Mycobacterium tuberculosis

Vaccines which offer better protection than BCG are now badly needed for controlling tuberculosis infection throughout the world. Immunological adjuvants capable of inducing a TH1 type of protective response are necessary to augment the immune response, particularly in the case of subunit vaccines. It is now well established that oligodeoxynucleotides (ODN) containing cytidine phosphate guanosine (CpG) motifs enhance cell-mediated responses in vivo by increasing the production of the TH1 cytokines IL-12 and interferon gamma (IFNgamma). To determine if this would improve subunit vaccination of mice CpG ODN were added to a subunit vaccine consisting of the culture filtrate proteins (CFP) of Mycobacterium tuberculosis H37Rv. It was observed that although adding CpG ODN to the vaccines promoted substantially increased IFNgamma production by lymph node cells draining sites of inoculation, this failed to translate after aerosol challenge into any degree of enhancement of bacterial clearance in the lungs, influx of IFN-positive T cells, or changes in histopathology. These data suggest that the vaccine enhancing effects of CpG ODN are relatively transient.     

SST-2 tumor inoculation is a useful model for studying the anti-tumor immune response in SHR rats

Objective The purpose of the present study was to investigate the relation between the dose of tumor cell inoculation (especially the doses less than minimum required to evoke tumor growth) and the anti-tumor immune system, particularly lymphoblast formation and cytotoxic activity of lymphcytes. Method We inoculated rats with various doses of SST-2 tumor cells and examined natural killer (NK) cell activity and lymphoblast formationin vitro. Result The results showed that the cytotoxicities against SST-2 cells and lymphoblast formation of lymphocytes were enhanced by small dose inoculation of tumor cells that could not induce tumor growth. Conclusion It was suggested that was lymphocutes play an important role as an anti-tumor immune system at small doses of tumor inoculation, which appears to reflect an early stage of tumor growthin vivo. It was also suggested that SST-2 tumor inoculation might be a useful model for studying the anti-tumor immune response in SHR rats.