人脐血间充质干细胞移植修复骨髓造血损伤

文题释义：间充质干细胞：是一种多功能干细胞,由胚胎发育早期的中胚层发展而来,存在于人的各种组织、器官中,如骨、软骨、脂肪、外周血和肌肉等。骨髓组织中的间充质干细胞最多,但其在骨髓细胞中的比例仍很低,只有0.01%-1.00%,且年龄越大其含量越少,骨髓中的间充质干细胞分化能力也呈下降趋势。与骨髓相比,脐血中所含的间充质干细胞更加原始,因而有更强的增殖、分化能力。相较于骨髓间充质干细胞而言,人脐血间充质干细胞具有来源广泛、取材方便、无伦理方面的限制,使得人脐血间充质干细胞成为再生医学中的另一重要来源。骨髓造血损伤动物模型：建立骨髓造血损伤动物模型的方法有很多,主要分为物理方法、化学方法及物理化学方法等。物理方法包括各种射线,如X射线等,化学方法主要指以环磷酰胺为代表的烷化剂类化疗药物,而物理化学方法也叫混合性方法,联合应用放射线和化疗药物建立动物模型。  摘要背景：大多数研究间充质干细胞体外培养对造血干细胞的增殖作用和骨髓间充质干细胞移植可降低辐照引起的造血细胞死亡,增加骨髓细胞存活,修复造血功能,而少有研究人脐血间充质干细胞移植对骨髓造血损伤的修复。目的：探讨人脐血间充质干细胞对骨髓造血微环境的修复情况。方法：选用雄性BALB/c小鼠随机分为3组,实验组和对照组小鼠进行总剂量为6 Gy的X射线全身照射,建立骨髓造血损伤模型,正常组为未经处理的正常小鼠。实验组小鼠照射当天经尾静脉输入CM-DiL标记的人脐血间充质干细胞5×10⁶/只(0.2 mL),对照组和正常组经尾静脉输入生理盐水0.2 mL,移植后第1,5,7,14,21天观察外周血血象恢复情况和骨髓造血微环境修复情况。结果与结论：①外周血常规：移植后第1,5,7天,实验组和对照组小鼠与正常组小鼠比较,白细胞、血小板、红细胞计数及血红蛋白浓度进行性下降,第7天下降最为明显,移植后第14天三系较前有所恢复,移植后第21天基本恢复正常,与实验组相比,对照组三系下降更为明显,移植后第14天实验组较对照组恢复快;②骨髓涂片情况：移植后第1,5,7,14天实验组及对照组小鼠骨髓出现造血功能抑制,以第7天最为明显,移植后第14天骨髓增生较前有所恢复,实验组优于对照组;移植后第21天实验组及对照组小鼠骨髓造血功能恢复,与正常组相比无差异;③骨髓病理切片情况：移植后第1,5,7,14天实验组及对照组小鼠骨髓出现造血功能抑制;移植后第14天实验组及对照组小鼠的骨髓造血功能较前开始恢复,实验组小鼠的骨髓增生情况优于对照组小鼠, 移植后第21天实验组及对照组小鼠骨髓增生情况与正常组比较无差异;④结果表明,人脐血间充质干细胞对骨髓造血功能恢复均有明显促进作用。ORCID: 0000-0002-7547-9664(高坤莉) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

D183.49壳聚糖对脐血造血干细胞移植小鼠免疫重建的研究

目的：探讨D183．49壳聚糖对脐血造血干细胞的体外扩增作用及其对脐血造血干细胞移植小鼠的免疫重建并初步探索对脐血造血干细胞移植有调控作用的药物筛选方法。方法：分离脐血中单个核细胞体外扩增培养，测定细胞增殖率及CD34^＋细胞数。60Coγ射线亚致死量照射小鼠，尾静脉注射扩增培养后的单核细胞，每日腹腔注射D183．49壳聚糖，28天。观察记录生存状况；测定血象及CD3、CD4、CD8、CD19水平；脾脏病理切片观察。结果：①体外研究：D183．49壳聚糖10μg组体外增殖效率最显著，48小时达峰值；流式细胞仪测定CD34^＋细胞扩增8倍，P〈0．01。②体内研究：移植药物小鼠血象恢复明显短于其他实验组；CD3、CD4、CD8、CD19水平基本恢复正常，P〈0．05。小鼠脾脏病理切片显示亦恢复正常。结论：D183．49壳聚糖对脐血造血干细胞有明显扩增作用，其能够促进脐血造血干细胞移植小鼠免疫造血重建。     

胸腺素能有效地修复辐射所致的造血组织损伤

胸腺素能有效地修复辐射所致的造血组织损伤为探讨胸腺素治疗造血功能障碍的作用原理，并观察其疗效，作者等以９００拉德Ｘ线全身照射小鼠３０只，造成造血功能障碍之模型，用胸腺素２ｍｇ／ｋｇ腹腔注射，１／ｄ，并设立对照组，观察小鼠外周血象，骨髓象和肝、脾、骨髓...     

高增殖潜能集落形成细胞的分类,富集与调控

高增殖潜能集落形成细胞（ＨＰＰ－ＣＦＣ）是存在于小鼠和人骨髓及入胎肝、脐血中的一类较为原始的造血祖细胞。它在体外培养中可产生直径大于０．５ｍｍ，５００００细胞／集落的巨大集落；对５－氟尿嘧啶有相对耐受性；对多种造血生长因子的刺激有反应性。     

细胞因子介导的人脐血单个核细胞体外扩增并重建NOD/SCID小鼠造血及免疫功能

背景:细胞因子介导的脐血造血细胞体外扩增有望能解决脐血移植数量不足的问题。目的:实验拟确立在无基质培养条件下体外扩增脐血单个核细胞最合适的细胞因子组合及干细胞因子、FLT3配基协同促聚核细胞生成因子对造血及免疫重建功能的影响。方法:将新鲜脐血标本分离的单个核细胞接种于含有不同细胞因子组合的无血清无基质培养体系中培养7d,根据不同细胞因子组合分组,将3因子干细胞因子+FLT3配基+促聚核细胞生成因子组合在无血清无基质条件下扩增培养7d前后的脐血单个核细胞移植给经亚致死量照射的NOD/SCID小鼠。在扩增培养0,7d检测脐血CD34+细胞数及CD34+CXCR4+,CD34+CD62L+,CD34+CD49d+的细胞数。脐血移植6周后通过流式细胞仪,PCR法检测存活小鼠体内的人源性细胞。结果与结论:移植6周后,存活小鼠体内均可检测到人源性CD45+细胞,扩增脐血移植组的NOD/SCID小鼠存活率和人特异性基因捡出率均高于新鲜脐血移植组和高于生理盐水移植组(P0.05)。扩增脐血组存活NOD/SCID小鼠骨髓中可检测到人髓系细胞(CD33+),T淋巴细胞(CD4+),B淋巴细胞(CD19+)和人造血干细胞成分(CD34+)细胞的表达。结果提示干细胞因子+FLT3配基+促聚核细胞生成因子3因子组合脐血造血细胞体外扩增是最合适的细胞因子组合,其扩增的脐血单个核细胞能够植入并重建NOD/SCID小鼠的造血及免疫功能。     

非黏附骨髓源干细胞治疗急性放射损伤

背景：目前对于辐射剂量超过8 Gy的急性放射病尚缺乏有效的治疗方案,间充质干细胞可以分泌多种造血因子、重建造血,在放射损伤救治中具有重要意义。 目的：探讨非黏附骨髓源干细胞在8.5 Gy X射线照射所致急性骨髓型放射损伤救治中的作用及作用机制。 方法：取胎儿四肢长骨的非黏附骨髓源干细胞,分析其麦面抗原,细胞周期,成骨和成脂分化潜能,以及血管内皮生长因子及Annexin A2表达。BALB/C小鼠受8.5 Gy一次性全身均匀X射线照射后随机分成骨髓源干细胞组和对照组,骨髓源干细胞组小鼠在X射线照射2 h内经尾静脉输注含3×106 CFDA-SE标记的人非黏附骨髓源干细胞的细胞悬液0.3 mL,对照组小鼠在X射线照射2 h内输注0.3 mL生理盐水。观察骨髓源干细胞的分布情况、小鼠的存活率、白细胞变化、骨髓病理变化及骨髓中新生血管形成情况。 结果与结论：X射线照射后移植的非黏附间充质干细胞可以向损伤部位归巢;骨髓源干细胞组小鼠存活率明显高于对照组;与对照组相比,骨髓源干细胞组小鼠外周血白细胞计数下降慢且恢复迅速,X射线照射后14 d左右达最低,30 d基本恢复至正常水平。X射线照射后21 d,骨髓源干细胞组骨髓增生活跃,骨髓腔内新生造血灶显著多于对照,血管密度亦显著高于对照组。说明人胎儿非黏附骨髓源干细胞促进急性放射损伤小鼠骨髓内新生血管形成,改善并加快受损小鼠造血功能的恢复。     

小鼠脐血造血干/祖细胞含量与特性初步观察

目的: 探讨小鼠脐血(umbilicalcordblood, UCB)造血干/祖细胞含量与特性。方法: 采用体外集落培养和流式细胞术检测C57BL/6(H-2^b)小鼠脐血与骨髓(bonemarrow, BM)造血干/祖细胞。结果: 小鼠脐血培养7d粒单系祖细胞(CFU-GM)及早期红系祖细胞(BFU-E)集落产率与骨髓相近, 但14dCFU-GM、多向祖细胞(CFU-GEMM)明显高于后者(P<0.05), 且见含细胞多体积巨大的致密型集落。脐血CD₃₄⁺Sca-1⁺细胞亚群也明显高于骨髓(P<0.05)。结论: 小鼠F脐血富含造血干/祖细胞, 具有高增殖潜能。     

人源化NOD/SCID小鼠的细胞免疫重建

目的探讨人脐带血CD34+细胞移植于非肥胖性糖尿病/重症联合免疫缺陷(NOD/SCID)小鼠后的免疫重建作用。方法免疫磁珠法分选人脐血CD34+细胞,经外侧尾静脉移植于亚致死量照射的NOD/SCID小鼠。移植后4、6、8、10周流式细胞术动态监测小鼠外周血人源CD45+、CD3+、CD56+细胞的数量;10周后PCR检测小鼠骨髓人ALU基因的表达,免疫组织化学染色检测小鼠脾脏人源CD3+、CD56+细胞的表达。结果 NOD/SCID小鼠经照射后骨髓腔内有核细胞及巨细胞数量均明显减少或消失,达到理想的清髓预处理效果;移植后4、6、8、10周,移植组所有存活小鼠外周血均可检测到人源性CD45+、CD3+、CD56+细胞的表达,人源淋巴细胞的数量随时间的延长而变化,8周时达到高峰,10周仍有较高的比例。10周时移植组所有存活小鼠骨髓细胞均检测到人ALU基因的表达,脾脏均检测到人CD3+、CD56+细胞;未移植组小鼠照射后2周内全部死亡。结论经照射后的NOD/SCID小鼠通过移植人脐血CD34+细胞成功地建立了hu-SRC-NOD/SCID模型,并有效地重建了小鼠细胞免疫系统。     

参麦注射液对60Co照射小鼠血液系统作用的研究

目的：观察参麦注射液(SMI)对于放射性损伤所致的小鼠血虚证的治疗作用。方法：采用^60Co照射小鼠，造成小鼠白细胞减少模型，即产生小鼠血虚证。评价SMI对于^60Co所致的小鼠血虚证的治疗作用。结果：SMI对^60Co照射所致小鼠血虚证症状如虚汗多、寒战、精神萎靡有一定程度的抑制作用，尤其对^60Co照射所致小鼠外周血白细胞和骨髓有核细胞数的减少有明显对抗作用，与模型组比较有显性差异(P＜0．05)。试验还显示，照射后四天SMI大、中剂量组小鼠骨髓有核细胞数与阴性对照组无显性差异，说明其骨髓造血功能比较活跃，提示SMI对放射性损伤所致小鼠血虚证有一定的保护和治疗作用，对于小鼠白细胞减少有较好的治疗效果。结论：SMl对小鼠放射性损伤所致血虚证有一定的保护和治疗作用。     

人脐血来源MSCs的主要生物学特性的研究

目的：探讨人脐血间充质干细胞（MSCs）分离、纯化、扩增、表面标志、免疫表型及其造血生长因子（HGFs）分泌等生物学特性方法：(1) Ficoll法分离、纯化人脐血、成人骨髓和胎儿骨髓MSCs，动态观察不同来源MSCs的生长状况。(2) 流式细胞仪检测脐血和骨髓MSCs表面CD34、CD45、CD14、CD29、CD44、CD105、CD166、CD80、CD86、CD40和CD40L的表达。(3) ELISA法检测脐血和骨髓MSCs培养上清中SCF、TPO、FLT-3L和IL-6的分泌水平。结果：(1) 所有骨髓标本中均可分离纯化出MSCs，而15份脐血中仅4份分离纯化出MSCs，脐血MSCs和骨髓MSCs的细胞形态无明显差异,脐血MSCs原代培养所需要的单个核细胞（MNC）量为骨髓MSCs的3倍，且其原代培养的增殖速度较慢，但脐血MSCs传代培养的增殖速度和骨髓相似。(2) 脐血MSCs和骨髓MSCs表面标志无差异，均不表达造血细胞表面标志以及与免疫识别有关的表面抗原。(3) 脐血和骨髓MSCs分泌SCF、TPO、FLT-3L和IL-6的水平相似。结论： (1)脐血和骨髓同样可以分离、纯化MSCs，但脐血中MSCs的含量少，且大部分脐血中不含MSCs。(2)纯化的脐血MSCs扩增能力、表面标志、免疫学表型及HGFs分泌水平和骨髓MSCs相似。     

骨髓间充质干细胞培养上清液治疗支气管哮喘及对肺部炎症的影响

背景：医学界普遍认为支气管哮喘是一种与Th2相关的免疫反应疾病,目前尚缺乏理想的治疗方法。骨髓间充质干细胞作为一种成体干细胞,不仅具有增殖和多向分化能力,还具有低免疫原性和免疫调节能力。 目的：探讨骨髓间充质干细胞培养上清液对支气管哮喘小鼠肺部炎症的影响。 方法：将20只实验小鼠随机分为对照组和实验组,每组10只,在第0天及第14天小鼠腹腔注射卵清蛋白溶液致敏,并在第24-26天雾化吸入卵清蛋白溶液激发。实验组从第24天开始,在每次激发前2 h,腹腔注射制备好的骨髓间充质干细胞培养上清液2 mL,对照组腹腔注射生理盐水。末次激发后麻醉致小鼠安乐死亡,采取血清、肺泡灌洗液及肺脏组织进行研究。 结果与结论：①对照组小鼠肺组织结构发生异常,黏膜下层和肌层内能够看见大量嗜酸性粒细胞及单核细胞浸润,经骨髓间充质干细胞培养液治疗后,实验组小鼠肺部炎症较轻。②实验组白细胞总数、嗜酸性粒细胞数、嗜酸性粒细胞百分比显著低于对照组(P < 0.01)。③实验组肺泡灌洗液以及血清中白细胞介素17水平显著低于对照组(P < 0.05);肺泡灌洗液以及血清中白细胞介素4水平与对照组比较差异无显著性意义(P > 0.05)。上述结果提示支气管哮喘小鼠腹腔注入骨髓间充质干细胞培养上清液能够减轻肺部炎性病理反应严重程度,降低肺泡灌洗液以及血清中相关的炎症指标水平。  中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程      

不同体积分数脐血血清与骨髓间充质干细胞的增殖

背景：制备脐血血清体外扩增、培养间充质干细胞成为目前的研究热点,但尚无不同体积分数脐血血清对骨髓间充质干细胞的增殖能力的影响的报道。 目的：观察比较不同体积分数的脐血血清对骨髓间充质干细胞的增殖能力的影响。 方法：无菌条件下取20例人骨髓标本,采用密度梯度离心法提取单个核细胞,分别用体积分数为5%,7.5%,10%,15%,20%的脐血血清+DMEM/F12培养基,行骨髓间充质细胞培养,取第3代细胞,用MTT法观察不同体积分数的脐血血清对间充质干细胞的增殖能力的影响。 结果与结论：在体积分数5%,7.5%,10%的脐血血清+DMEM/F12培养基组,细胞增殖能力较佳,明显优于体积分数15%,20%的脐血血清+DMEM/F12培养基组,差异有显著性意义(P < 0.05)。说明在较低体积分数脐血血清培养体系中,骨髓间充质干细胞增殖状态活跃。     

胎儿骨髓源性亚全能干细胞分离培养及诱导肝细胞分化研究

目的研究分离胎儿骨髓源性亚全能干细胞及体内、外向肝细胞分化的潜能。方法利用密度梯度离心结合免疫磁珠方法分离胎儿骨髓源性亚全能干细胞，体外培养鉴定，诱导分化。制备肝功能衰竭重度联合免疫缺陷小鼠（severe combined immunodeficiency，SCID）模型。肝原位输注106左右CD105^＋细胞，对照组分别输注106左右的CD105^-细胞或同等体积的培养液。移植细胞后2d、7d、1个月、3个月时分别取3只鼠的血清及组织标本行肝功能和病理学、免疫组织化学检测。结果免疫磁珠筛选后的免疫细胞化学检测CD105呈弱阳性表达；细胞在对数生长期的倍增时间为30h左右；约传10代后进入衰退期；SCID鼠移植细胞3个月后用鼠抗人白蛋白抗体检测小鼠肝脏中的人白蛋白，可见有点状或小灶状表达。结论来源于胎儿骨髓的亚全能干细胞可以在体外及肝脏微环境下转化为肝细胞样细胞。因此进一步深入研究组织微环境在细胞转化中的机制有十分重要的意义，将为开发诱导胎儿骨髓亚全能干细胞的多向分化潜能提供理论依据。     

骨髓间充质干细胞移植治疗系统性红斑狼疮

BACKGROUND: The non-specific immune suppression method is generally used for treatment of systemic lupus erythematosus, but poor prognosis, such as infection and high recurrence rate, exists. OBJECTIVE: To evaluate the therapeutic effect of bone marrow mesenchymal stem cell transplantation on systemic lupus erythematosus in mice. METHODS: Sixteen mice with systemic lupus erythematosus were equivalently randomized into control and experimental groups, or then subjected to passage 3 bone marrow mesenchymal stem cell transplantation or the equal volume of normal saline via the tail vein, respectively. Mouse urine samples were collected to detect urine protein levels by Bradford method. Blood samples from the tip of the mouse tail were extracted to detect serum anti-ds-DNS antibody concentration by radioimmunoassay. Mouse kidney tissues were taken and observed pathohistologically through hematoxylin-eosin staining and immunohistochemistry staining under microscope. Flow cytometry was used to detect the expression of CD4+CD25+T cells in the inner canthus blood, fresh spleen and thymus. RESULTS AND CONCLUSION: Within 10 weeks after cell transplantation, the urine protein levels in the two groups were gradually increased, and the rising velocity was higher in the control group than in the experimental group. From the 4th to 10th week, the urine protein levels in the experimental group were significantly lower than those in the control group (P < 0.05). In the control group, lymphocyte infiltration was visible in the kidney tissues with a few of plasmocytes, and pathological findings showed the mice presented with interstitial nephritis; in the experimental group, the mice had no pathological changes in the kidney. In the two groups, immune complexes were found in the mesangial area, which showed a patch-like distribution in the control group and a punctate distribution in the experimental group; the relative proportion of the occupied area in the experimental group was significantly lower than that in the control group. The expression level of CD4+CD25+T cells in the blood and thymus were significantly higher in the experimental group than the control group (P < 0.05), and the expression level of CD4+CD25+T cells in the spleen was slightly higher in the experimental group than the control group with no significant difference (P > 0.05). The serum anti-ds-DNA antibody concentration in the experimental group was significantly lower than that in the control group (P < 0.05). Taken together, bone marrow mesenchymal stem cell transplantation can improve the pathological damage in systemic lupus erythematosus mice, and has a certain therapeutic effect on systemic lupus erythematosus.       

养正合剂和粒细胞集落刺激因子对化疗后骨髓功能的影响

目的:探究养正合剂和粒细胞集落刺激因子对化疗后骨髓功能的影响.方法:50只健康雌性C57BL/6小鼠以环磷酰胺(CTX)致骨髓功能抑制模型后随机分为空白组、模型组、rhG-CSF组、养正合剂1组、养正合剂2组,10只/组,连续5 d分别给予生理盐水0.2 ml、生理盐水0.2 ml、重组人粒细胞-巨噬细胞集落刺激因子(...     

Bone regeneration by grafting of cultured human bone

A 3-mL sample of bone marrow was collected from the iliac bones of 27 orthopedic patients (8 men and 19 women with a mean age of 56.1 years [range, 17 to 76 years]), followed by culture in standard culture medium (minimal essential medium containing 15% fetal bovine serum). In all 7 patients randomly selected from these 27 patients, significant in vitro osteogenic ability of marrow mesenchymal cells was demonstrated by scanning electron microscopy and biochemical analyses. In all 27 cases, to investigate the in vivo osteogenic potential of this human cultured bone, porous ceramics were impregnated with marrow cells and subcultured in osteogenic culture medium (standard medium supplemented with sodium beta-glycerophosphate, vitamin C phosphate, and dexamethasone). After 3 weeks of subculture, the cultured artificial bones of the cultured bone/porous ceramics were grafted into the abdominal cavity of nude mice. Histological and biochemical (alkaline phosphatase activity and human osteocalcin) examinations indicated that the cultured artificial bone possessed significant ability to regenerate bone. This result suggests that the bone-regenerating ability of human marrow cells may not depend on age, and that cultured artificial bone may be useful for bone regeneration treatment if appropriate cultured marrow cells can be successfully prepared.     

Murine serum obtained from bone marrow-transplanted mice promotes the proliferation of hematopoietic stem cells by co-culture with MS-5 murine stromal cells

To examine whether serum obtained from bone marrow-transplanted mice can selectively expand hematopoietic stem cells (HSCs) among whole bone marrow cells in vitro, whole bone marrow cells were cultured with or without MS-5 murine stromal cells in the presence of serum obtained from transplanted mice on day 3 (day 3 serum) or serum from normal mice for 7 days. When whole bone marrow cells and MS-5 cells were co-cultured in day 3 serum for 7 days, the c-kit-positive, Sca-1-positive, lineage marker-negative cells (KSL cells) expanded approximately 25 times; however, when they were co-cultured in normal serum for 7 days, the KSL cells expanded approximately 1.3 times. Direct contact between the whole bone marrow cells and MS-5 cells was essential for expansion of KSL cells in the co-culture, and it upregulated the expression of some cytokines in MS-5. Above all, the day 3 serum specifically upregulated the expression of SCF, SDF-1 alpha, G-CSF, IL-11 and IL-6 in MS-5. The level of testosterone in the day 3 serum was higher than normal serum and the addition of the testosterone in the culture expanded the KSL cells among whole bone marrow cells on MS-5 cells and also upregulated the expression of SDF-1 alpha, IL-11 and IL-6 in MS-5. These data indicates that the serum of bone marrow-transplanted mice contains a factor(s) that induced changes in the expression levels of various cytokines in MS-5 stromal cells and enabled the MS-5 cells to expand the KSL cells among whole bone marrow cells.     

骨髓干细胞移植后mdx鼠腓肠肌病理变化

目的 研究骨髓干细胞移植后mdx鼠腓肠肌组织病理变化. 方法 7～9周龄mdx鼠20只平均分为4组,放射处理后移植1.2×107细胞/只同种异基因全骨髓干细胞,于移植后4、8、12及16周用HE染色观察腓肠肌组织细胞形态及核中心移位纤维(CNF).C57鼠和未治疗mdx鼠各5只作阳性和阴性对照. 结果 CS7鼠腓肠肌横切面可见肌细胞大小形态基本一致,无核中心移位现象.各细胞移植治疗组和阴性对照组mdx鼠均有大量的炎细胞浸润,核中心移位明显.未治疗mdx鼠CNF最高,约达70%;移植后4、12和16周,CNF分别为55%、50%和44%. 结论 骨髓干细胞移植后mdx鼠腓肠肌CNF随移植时间延长逐渐减少,提示骨髓干细胞移植后长久持续参与受损骨骼肌的修复与再生.     

Effect of cyclophosphamide on the immune response to Pseudomonas aeruginosa in mice.

Natural resistance in mice to Pseudomonas aeruginosa was decreased 10-fold with a single dose of 300 mg of cyclophosphamide (CY) per kg intraperitoneally. Mice were resistant to infection when immunized actively with Pseudomonas vaccine or passively with Pseudomonas immune serum before receiving CY. Syngeneic spleen, thymus and/or bone marrow cells were transfused into CY-treated recipient mice. Protective anti-Pseudomonas antibody was elicited in the recipient mice when they were vaccinated 1 day after receiving normal spleen cells and challenged 8 days after vaccination. When 1.6 X 10(7) normal thymus and bone marrow cells were infused before vaccination, 69% of the recipients of both cell preparations responded serologically compared with 15 and 27% of those receiving either thymus or bone marrow cells, respectively. CY-treated thymus or bone marrow cell recipients were resistant to Pseudomonas infection when 6 X 10(7) of either cell population was transfused.