氟尿嘧啶、呋氟尿嘧啶对小鼠免疫功能的影响

本研究检测了5-Fu和FT-207对昆明种小鼠的免疫毒性。主要指标为免疫器官的相对重量，淋巴细胞计数和外周血淋巴细胞ANAE阳性率及血清初次抗SRBC抗体和抗体形成细胞功能。实验结果表明；5-Fu，FT-207在本实验条件下对小鼠胸腺和脾脏的相对重量影响较轻，但可导致小鼠T淋巴细胞数量的显著降低，大剂量时对小鼠体液免疫水平也有明显的抑制作用。     

油菜蜂花粉及其丙酮提取物对免疫增强作用的研究

本文观察了油菜蜂花粉及其丙酮提取物对正常和由于免疫抑制剂环磷酰胺、荷瘤及抗淋巴细胞血清所致免疫低下小鼠的免疫增强作用。结果表明,蜂花粉及其丙酮提取物对正常幼年和成年小鼠能提高血清抗SRBC抗体的含量(HC_(50))和增加脾脏空斑形成细胞(PFC)。蜂花粉丙酮提取物对环磷酰胺、荷瘤及抗淋巴细胞血清等所致免疫低下小鼠的血清抗SRBC抗体、定量脾细胞体外分泌抗SRBC抗体(QHS)、脾脏空斑形成细胞(PFC)和特异玫瑰花形成细胞(SRFC)减少均有明显对抗作用。上述结果提示,油菜蜂花粉及其丙酮提取物有免疫增强作用,丙酮提取物可能是该花粉所含一种增强兔疫作用的活性物质。     

外源核苷酸对免疫抑制小鼠胸腺细胞DNA损伤的影响

目的:检测外源核苷酸对经环磷酰胺诱导的免疫抑制小鼠胸腺细胞DNA损伤的影响。方法:采用18～20 g昆明种小鼠30只,雌雄各半,随机分成阴性对照组(NEC)、阳性对照组(POC)和核苷酸组(NTG),每组10只。NEC组和POC组小鼠均饲喂半纯合无核苷酸的基础日粮,NTG组则在基础日粮中添加0.25%的核苷酸,实验期为21 d。在实验结束前18 h POC组和NTG组小鼠按照150mg/kg bw的剂量腹腔注射环磷酰胺,NEC组注射生理盐水,实验结束时测定脾脏和胸腺脏器指数,并取胸腺细胞,做单细胞凝胶电泳,观察细胞DNA损伤情况。结果:在基础日粮中添加核苷酸对小鼠免疫器官重量没有显著影响(P>0.05),但能极显著降低受损胸腺细胞百分率(P<0.01)和受损细胞DNA尾长(P<0.01)。结论:外源核苷酸能显著降低免疫抑制小鼠受损胸腺细胞百分率和损伤程度。     

醋酸舍莫瑞林的免疫活性研究

目的　观察醋酸舍莫瑞林对免疫抑制模型小鼠免疫功能的调节作用。方法　通过给小鼠腹腔注射免疫抑制剂环磷酰胺 ,建立免疫功能低下模型 ,腹腔注射醋酸舍莫瑞林进行体内拮抗实验。测定胸腺指数、脾脏指数、巨噬细胞吞噬功能、T淋巴细胞的增殖指数、耳肿胀度、血清IL - 2的含量。结果　醋酸舍莫瑞林 ( 0 18,0 36mg/kg)能显著提高被环磷酰胺抑制的胸腺和脾脏重量 (P <0 0 1) ;使巨噬细胞吞噬功能明显增加 ,并能拮抗环磷酰胺对小鼠脾脏T淋巴细胞增殖、二硝基氯苯 (DNCB)诱导的迟发型超敏反应和IL - 2产生的免疫抑制作用。结论　醋酸舍莫瑞林能拮抗环磷酰胺所引发的免疫抑制作用     

外源核苷酸对小鼠胸腺细胞凋亡的影响

目的 探讨外源核苷酸对小鼠胸腺细胞凋亡的影响。方法 首先建立了体内细胞凋亡模型,25只4周龄雄性小鼠腹腔注射地塞米松(25mg／kg)4、8、16、24h后取胸腺淋巴细胞进行细胞凋亡检测。确定建立体内细胞凋亡模型的条件为注射地塞米松(25mg／kg)后16h取小鼠胸腺细胞。外源核苷酸对小鼠胸腺淋巴细胞凋亡的影响,60只小鼠分成阴性对照、阳性对照、核苷酸1组、核苷酸2组,共4组,每组15只小鼠,均饲喂半纯合饲料。对照组每天灌胃生理盐水,核苷酸1组和2组分别灌胃12．5mg和25mg的核苷酸,连续饲养14d后阳性对照组和核苷酸组小鼠腹腔注射地塞米松溶液,诱导小鼠胸腺淋巴细胞凋亡,阴性对照组注射等量的生理盐水,16h后分离脾脏和胸腺,测定脾脏及胸腺指数,并采用琼脂糖凝胶电泳和流式分析方法检测胸腺淋巴细胞凋亡情况以及细胞游离Ca^2 浓度([Ca^2 ]i)。结果 核苷酸1组和2组小鼠的增重分别为3．71、4．01g,阴性对照组小鼠增重为2．74g,注射地塞米松后阳性对照组和核苷酸组小鼠的脾脏、胸腺重量以及脏器指数低于阴性对照,添加核苷酸对这些脏器指数没有明显影响;注射地塞米松后小鼠胸腺细胞DNA出现梯形条带,注射地塞米松后阳性对照组和核苷酸组小鼠胸腺细胞内Ca^2 水平分别升高至167．37nmoL／L、191．16nmol／L、180．78nmol／L,高于阴性对照(103．76nmoL／L)。细胞凋亡率也分别由阴性对照组的0．31％升高到11．93％、9．82％、11．15％,补充核苷酸对细胞内Ca^2 水平和细胞凋亡率均没有显著影响。结论 外源核苷酸对地塞米松诱导的小鼠胸腺细胞凋亡没有显著影响。     

玉竹对小鼠免疫抑制调节作用的研究

目的：研究玉竹对免疫功能的影响。方法：将昆明种小鼠分为空白对照组、模型组、玉竹水煎液组及香菇菌多糖阳性对照组,腹腔注射给药环磷酰胺3d造成小鼠免疫抑制模型,同时分别灌胃给药生理盐水及相应药物7d后测定玉竹对小鼠胸腺、脾脏质量、吞噬百分率、吞噬指数、溶血素、溶血斑以及淋巴细胞转化率的影响。结果：玉竹能提高环磷酰胺造成免疫抑制模型小鼠胸腺、脾脏质量、吞噬百分率、吞噬指数,促进溶血素、溶血斑形成,提高淋巴细胞转化率;与模型组相比可提高免疫抑制小鼠各免疫指数,比较差异有统计学意义（P〈0.01）。结论：玉竹具有增强免疫作用的功能。     

茯苓多糖对荷瘤小鼠及老年人和肿瘤患者免疫功能影响的探讨

作者用小鼠作试验模型,采用灌胃的方法,观察了茯苓多糖对荷瘤小鼠的抑瘤率及免疫功能的影响。结果表明茯苓多糖剂量在250mg/kg/d抑瘤率最好(51.8％),并能增强小鼠的Mφ吞噬功能(P<0.01),增加ANAE阳性淋巴细胞数(P<0.05)。还能使小鼠脾脏抗体分泌细胞数PFC明显增多(P<0.01),在一定的剂量范围内起到抗胸腺萎缩及抗脾脏增大,保护免疫器官的作用。另从老年人免疫功能测试结果发现,茯苓多糖有促进细胞免疫的功能,显示其Ea、LCT、T_3、T_4均有增高(P<0.05)及调整TC亚群的比值。在对肿瘤患者免疫功能的检测中,结果显示茯苓多糖同样有促进细胞免疫功能作用。     

龟鹿口服液对小鼠免疫功能影响的实验研究

目的　了解龟鹿口服液对小鼠免疫功能的影响。方法　采用雌性昆明种小鼠经口连续给予 2 5、5 0、15 0ml/kg·bw的龟鹿口服液 30d ,进行迟发型变态反应 (足跖厚度增加法 )、小鼠脾淋巴细胞转化试验、溶血素滴度测定、抗体生成细胞检测等试验。结果　受试物对小鼠的体重、脾脏和胸腺重量无明显影响 (P >0 0 5 ) ;对小鼠迟发型变态反应试验中 ,各剂量组足跖增厚值均高于对照组 ;对ConA诱导的小鼠脾淋巴细胞转化试验 ,低剂量组吸光度差值高于对照组 ;对受试动物血清溶血素抗体滴度水平的影响 ,中、高剂量组的抗体积数高于对照组 ;对受试动物脾细胞抗体生成水平的影响 ,各剂量组的脾细胞抗体生成水平 (空斑数 )均高于对照组 ,差异均有显著性 (均P <0 0 5 )。对小鼠碳廓清吞噬功能和对小鼠腹腔巨噬细胞吞噬鸡红细胞吞噬功能以及NK细胞活性测定中 ,各剂量组与对照组比较 ,差异均无显著性 (均P >0 0 5 )。结论　龟鹿口服液具有增强小鼠细胞和体液免疫功能的作用。     

锌中毒对雏鸭免疫系统结构及其功能影响的研究

目的 :　探讨锌中毒对免疫器官结构和功能的影响及其机制。方法 :　通过建立雏鸭锌中毒模型 ,应用免疫组织病理学方法检测雏鸭胸腺、腔上囊、脾脏绝对重量及指数、生长周期、外周血 T淋巴细胞 ANAE+ 阳性率 ,红细胞 C3b、CIC花环率以及观察免疫器官显微、超微病理组织学变化。结果 :　 (1 )锌中毒组 (ZT)体重 2 1日龄以后极显著低于锌对照组 (ZC,P<0 .0 1 )。 (2 )ZT胸腺、腔上囊 2 w龄以后、脾脏 3 w龄以后其绝对重量均极显著低于 ZC(P<0 .0 1 )。 (3 ) ZT胸腺、腔上囊、脾脏细胞周期的静止期细胞明显增高 ,而增殖期细胞下降 ,与 ZC比较差异极显著 (P<0 .0 1 )。(4 ) ZT2～ 4w龄外周血 T淋巴细胞 ANAE+阳性检测率极显著低于 ZC(P<0 .0 1 )。 (5 )显微镜下 ZT胸腺、腔上囊、脾脏淋巴细胞数量显著减少 ,排列稀疏 ;电镜下淋巴细胞线粒体受损 ,网状细胞均含有大量各级溶酶体、吞噬体。 (6) ZT红细胞 C3b RR花环率极显著低于 ZC组 (P<0 .0 1 ) ,而红细胞 CIC花环率却极显著高于 ZC(P<0 .0 1 )。结论 :　锌中毒严重抑制雏鸭免疫器官的发育 ,造成明显的病理损伤 ,导致细胞、体液、红细胞免疫功能下降     

饮食核酸对不同龄小鼠免疫功能的影响

目的　探讨饮食核酸对小鼠增龄性免疫功能变化的影响。方法　选取青龄 ( 1 2周龄 C57BL/6)、老龄 ( 1 5月龄 BALB/c)小鼠各随机分为 3组 ,在普通饮食饲喂的基础上 ,各组分别每日灌胃 2 0 mg/kg bw的低剂量、1 0 0 mg/kg bw的高剂量饮食核酸提取物 (低、高剂量实验组 )和0 .1 mol/L的柠檬酸钠缓冲液 (对照组 ) ,另选 6周龄 BALB/c小鼠作为幼龄对照组 ,每日灌胃柠檬酸钠缓冲液。观察中枢免疫器官胸腺与外周免疫器官脾脏的脏器指数、脾淋巴细胞 DNA合成能力、细胞因子白介素 - 2 ( IL- 2 )及肿瘤坏死因子 ( TNF)活性的变化。结果　青龄鼠高、低剂量饮食核酸补充组与其对照组比 ,胸腺指数、脾脏指数、脾淋巴细胞增殖能力、IL- 2及 TNF活性均显著增加( P<0 .0 5) ,但不同剂量核酸补充组间无显著差异。老龄鼠高剂量核酸补充组的胸腺指数、脾淋巴细胞增殖能力、IL- 2及 TNF活性均显著高于低剂量核酸补充组和其对照组 ( P<0 .0 5) ;但胸腺指数高剂量核酸补充组仍低于幼龄对照组 ,低剂量核酸补充组脾淋巴细胞增殖能力和 IL- 2活性也明显高于其对照组 (差异均为 P<0 .0 5) ;低剂量核酸补充组 IL - 2和 TNF活性与幼龄组间无差异。结论　饮食核酸既是生命早期和维持正常免疫的必需营养物质 ,还可显著改善小鼠增龄性?     

Relationship between serum zinc level and immunocompetence in protein-deficient and well-nourished weanling mice

Two experiments were performed in which three-week-old male and female CBA/J mice were fed adlibitum for two weeks either a control diet (18.6% protein) containing adequate levels of all nutrients or a lowprotein diet (Experiment 1: 1.6%; Experiment 2: 0.6%) adequate in all other nutrients. Two thymus-dependent primary immune responses to sheep red blood cells (SRBC), viz. the antibody (hemagglutinin) response and the low-dose delayed hypersensitivity response, were tested in each experiment. Mice fed 1.6% protein maintained weaning weight, but exhibited low thymic and splenic indices (weight relative to body weight), low serum protein levels and low serum zinc levels. These animals, however, displayed normal immune responses to SRBC. Mice fed 0.6% protein lost about 15–20% of their initial (weaning) weight during the 14-day experiment, and exhibited low thymic and splenic indices, low serum protein levels and low serum zinc levels. Both the antibody response and the delayed hypersensitivity reaction were depressed in these animals. Subcutaneous zinc injections raised the serum zinc level to nearnormal in mice fed 0.6% protein, but did not influence either immune response examined. By contrast parenterally administered zinc reduced the antibody response of well nourished mice to about 15% of normal, although the delayed hypersensitivity response was not affected in this group of animals. A negative correlation (R=?0.72, P<0.02) was found between serum zinc level and hemagglutinin titer in the zinc-injected, well-nourished animals. The results suggest that thymus-dependent immune responses are highly resistant to the adverse effects of protein deficiency, but do not support the hypothesis (proposed by others) that secondary zinc deficiency is a primary underlying cause of the immunodepression which occurs in severe protein deficiency. In addition, it appears that zinc supplements can depress some immune responses of well-nourished individuals if the quantities administered overwhelm the mechanism(s) regulating serum zinc level.     

不同硒营养和运动对小鼠免疫和抗氧化功能的影响

目的：　研究小鼠长期训练时不同硒营养对免疫、抗氧化功能的影响。方法：　四周龄 Ｃ５７ Ｂ Ｌ／６ Ｊ雄性小鼠按饲料硒水平分为低硒、正常硒、补硒组。每组分为两个亚组：训练组和安静组。各组喂以相同饲料,但给适硒,补硒组添加硒酸钠,使饲料硒水平分别为０ ．０３ 、０ ．２０ 和０ ．５０ ｍ ｇ／ｋｇ 。训练方式为游泳,每天１ 小时,每周５ 天,持续１０ 周。最后一次训练后７２ 小时宰杀,安静对照小鼠同时宰杀。结果：　（１） 补硒状态下长期训练使肝硒、 Ｇ Ｓ Ｈ Ｐｘ 活性显著增加,但这种训练调节在缺硒状态没有发生;低硒状态下长期训练损害了机体抗氧化功能,使 Ｇ Ｓ Ｈ Ｐｘ／ Ｍ Ｄ Ａ 比值显著下降, Ｍ Ｄ Ａ 浓度显著升高。（２） 长期训练使补硒的小鼠脾淋巴细胞 Ｓ Ｉ（ Ｌ Ｐ Ｓ） 和 Ｓ Ｉ（ Ｃｏｎ Ａ） 显著升高,使低硒的小鼠外周血 Ａ Ｎ Ａ Ｅ＋ ％ 显著下降。补硒使训练组小鼠 Ｓ Ｉ（ Ｌ Ｐ Ｓ） 和 Ａ Ｎ Ａ Ｅ＋ ％ 显著升高,而低硒使训练组小鼠 Ｓ Ｉ（ Ｃｏｎ Ａ） 显著下降。（３） 安静对照状态下,硒与机体抗氧化和免疫功能的关系都不明显,而长期训练的小鼠抗氧化功能与免疫功能之间以及硒与二者之间都有显著性相关关系。结论：　补硒有益于运动机?     

Sodium periodate-induced suppressor cell function in short and long-term calorie restriction

To study the effect of calorie restriction on the suppressor function of sodium periodate-treated spleen cells, C57BL/6 mice were distributed one week after weaning into two groups. The control normal group (N) was fed ad libitum a normal diet and the calorie restricted group (R) received on a daily basis 60% of the average food intake of the N group for 3 to 10 weeks. Following in vivo primary immunization with sheep red blood cells (SRBC) i.p., the number of nucleated spleen cells and of plaque forming cells (PFC) per spleen was significantly diminished in the R mice but the proportion of PFC per 10⁷ spleen cells was similar in either group. Pretreatment with sodium periodate induced significant suppression of the PFC response of N spleen cells to in vitro stimulation with SRBC but did not depress significantly the PFC response of spleen cells from mice kept on the restricted diet for either 3 or 10 weeks. Addition of 2×10⁶ periodate-treated N spleen cells to cultures of 10⁷ fresh spleen cells from normally fed mice, markedly suppressed the PFC response in all the experiments, whereas addition of similar number of periodate-treated R spleen cells caused less suppression of the PFC response. The results demonstrate that periodate-induced suppressor cell activity is impaired in short or long-term calorie restriction.     

Effect of a mixture of conjugated linoleic acid isomers on growth performance and antibody production in broiler chicks

The effect of dietary conjugated linoleic acid (CLA) isomers mixture on antibody titres against sheep blood erythrocytes (SRBC) and immunoglobulin (Ig) G concentration in plasma was studied in broiler chickens. In experiment 1, male and female broiler chicks (11 d of age, Cobb strain) were fed a diet supplemented with 10 g CLA or 10 g safflower-seed oil/kg diet for 2 weeks. An SRBC suspension (5:100, v/v) in a phosphate buffer was intravenously injected at 18 d of age and a blood sample was taken from the wing vein at 25 d of age. Chicks fed the CLA-supplemented diet had enhanced first antibody titres in plasma to SRBC as compared with those fed the safflower-seed oil-supplemented diet, irrespective of sex differences. In experiment 2, male broiler chicks (8 d of age, Ross strain) were fed a basal diet or a diet containing 10 g CLA/kg diet for 3 weeks. CLA in the CLA diet partially replaced the soyabean oil in the basal diet. The SRBC suspension was intravenously injected at 15 and 25 d of age and a blood sample was obtained at 21 and 29 d of age. The first antibody titres against SRBC were higher in chicks fed the CLA diet than those in chicks fed the basal diet, but the second titres were not. Plasma IgG concentrations in chicks fed the CLA diet were higher than those in chicks fed the basal diet on both sampling days. The results showed that dietary CLA enhanced antibody production in broiler chickens.     

超营养剂量酵母硒对荷瘤小鼠抗氧化和免疫机能的影响

目的:研究超营养剂量酵母硒对荷瘤小鼠抗氧化状态和免疫功能的影响。方法:60只昆明小鼠随机分为三组:对照组、酵母硒Ⅰ组和Ⅱ组,小鼠饲喂低硒日粮,对照组灌服0.5 ml生理盐水,酵母硒Ⅰ组和Ⅱ组灌胃酵母硒,剂量分别为3.2μg/d和6.4μg/d,D13小鼠接种艾氏腹水癌(EAC),试验结束测定血液抗氧化指标和免疫指标。结果:酵母硒Ⅰ组和Ⅱ组均能提高肿瘤移植小鼠血液谷胱甘肽过氧化物酶活性(P<0.05)和超氧化物歧化酶活性(P<0.01),但仅酵母硒Ⅱ组显著降低脂质过氧化值(P<0.05);酵母硒Ⅱ组显著提高NK细胞活性、巨噬细胞吞噬功能和迟发变态反应程度、血清抗绵羊红细胞抗体水平,酵母硒Ⅰ组与对照组差异不显著。结论:超营养剂量酵母硒的抑瘤机制可能主要是抗氧化作用和免疫调节作用,且作用与剂量有关。     

外源核苷酸对脂多糖刺激小鼠的保护作用及其机制研究

目的:研究外源核苷酸对脂多糖(LPS)刺激小鼠的保护作用,并探讨其可能机制。方法:采用刚断奶的昆明种仔鼠40只,按体重随机分成五组:对照组、核苷酸(NT)组(4h、18h)、无核苷酸(NF)组(4h、18h),对照组和NF组饲喂无核苷酸半纯合基础日粮;NT组饲喂含0.25%核苷酸混合物的日粮,在实验的D15,NT组和NF组灌胃LPS,对照组灌胃同等剂量的无菌生理盐水,在灌胃后的4h、18h,收集血清,无菌取肝、小肠、腹腔巨噬细胞待测。结果:日粮中添加核苷酸能显著升高LPS刺激小鼠肝Na+K+-ATP酶、小肠超氧化物歧化酶(SOD)活性、血清总抗氧化能力(T-AOC)和腹腔巨噬细胞分泌的抗炎性细胞因子白介素10(IL-10)的水平,降低小肠丙二醛(MDA)含量、血清谷丙转氨酶(AIL)、小肠髓过氧化物酶(MPO)活性和腹腔巨噬细胞分泌的炎性细胞因子白介素1(IL-1)的水平。结论:小鼠在受到LPS刺激时,在无核苷酸日粮中添加核苷酸有助于维持机体氧化/抗氧化、炎症/抗炎症平衡,保护机体免受损伤。     

二甲基苯蒽对金属硫蛋白基因敲除小鼠免疫功能的影响

目的：观察二甲基苯蒽（DMBA）对金属硫蛋白（MT）基因敲除小鼠[MT（－／－）]的免疫毒性。方法：选用MT（－／－）小鼠和MT（＋／＋]野生型小鼠进行对照,DMBA25mg/kg和50mg/kg分别1次腹腔注射染毒后,检测动物对静脉注射绵羊红细胞（SRBC）诱导的体液和细胞免疫反应,体液免疫指标为脾脏抗体形成细胞（PFC）数量变化,细胞免疫功能指标选择迟发型变态反应,即动物足跖肿胀厚度变化。结果：DMBA25mg/kg组,MT（－／－）小鼠脾脏和胸腺重量都减轻,体液免疫功能受到抑制（抑制率为72％）,而MT（＋／＋）小鼠仅脾脏重量减轻,两种小鼠的细胞免疫功能均未见明显变化,DMBA50 mg/kg组,MT（－／－）小鼠的体液免疫和细胞免疫功能受到抑制程度均比DMBA25mg/kg组严重（抑制率分别为91％和72％）。MT（＋／＋）小鼠虽脾脏和胸腺重量减轻,体液免疫受到抑制,但变化程度明显小于MT小鼠（－／－）。MT（＋／＋）小鼠没有出现明显的细胞免疫功能抑制。结论：MT（－／－）小鼠的体液免疫和细胞免疫功能更易被DMBA抑制。提示MT具有保护DMBA所致免疫伤的功能。     

Dietary nucleotide effects upon murine natural killer cell activity and macrophage activation

Weanling mice fed chow or chow plus water supplemented with 3.5 mg of nucleotides per 100 ml of water for 6 weeks exhibited increased natural killer cell (NK) activity and lower macrophage activation compared to mice fed chow plus nonsupplemented water. In a dose-response study, NK activity, macrophage activation and spleen weight (as a percentage of body weight) were higher in mice fed up to 0.035% w/w nucleotides, however macrophage activation was decreased by feeding over 0.35% w/w compared to those receiving basal purified diet (BPD). Nucleotides in human milk may affect the immune response in breast-fed infants.     

Fish oil and tocopherol-induced changes in natural killer cell-mediated cytotoxicity and PGE2 synthesis in young and old mice

Natural killer cell (NK) activity decreases and prostaglandin E2 (PGE2) level increases in aged mice. Because PGE2 is involved in control of NK activity this study was conducted to investigate whether or not decreasing PGE2 level by changing the type of dietary fat or increasing the level of vitamin E (vit. E) modulates NK activity of young and old mice. Mice were fed either a corn oil (CO) or a fish oil (FO) diet supplemented with 30 or 500 mg/kg diet of vit. E for 6 wk. To study the effect of vit. E during active immune response and oxidative stress, groups of old mice fed CO and either 30 or 500 mg/kg diet of vit. E were injected with sheep red blood cells (SRBC) prior to assessment of their NK activity. As reported by others regarding mice fed a nonpurified diet, the old mice in all dietary groups had significantly less NK activity and tended to synthesize more PGE2 than young mice. FO-fed mice synthesized less PGE2 than CO-fed mice; however, their NK activity was not higher than that of CO-fed mice. By contrast young mice fed FO had a moderately lower NK activity than those fed CO. Vit. E supplementation did not change NK activity in nonimmunized mice but was effective in preventing SRBC-induced decrease in NK activity of old mice.