八株小鼠胸腺基质细胞系产生白细胞介素1及白细胞介素6的水平

应用IL-1诱导LBRM33-IA5细胞产生IL-2、及支持IL-6依赖细胞系KD-83细胞的增殖,分别测定了本室所建8株小鼠胸腺基质细胞系自发分泌IL-1及IL-6的能力.8株MTSC 分泌IL-1水平不同,>100U/ml者,1株;30～40U/ml 者,2株.8株细胞均能产生IL-6,其中7株的分泌水平>80U/ml;1株为38U/ml.比较各株分泌IL-1及IL-6的水平,本文显示,在MTSC 各系中,尚存在IL-1非依赖性IL-6分泌途径.本文尚比较了两种测定IL-1活性的方法,支持胸腺细胞增殖法测得者,实为IL-1+IL-6的效应,不能反映IL-1的实际水平.     

小鼠胸腺基质细胞系MTDC的鉴定及细胞因子对其表面分子表达的作用

目的：鉴定小鼠胸腺基质细胞系MTDC，为进一步功能研究奠定基础。方法：利用多种鉴定小鼠胸腺树突状细胞的单克隆抗体对我室建立的一株缺乏上皮细胞典型特点的胸腺基质细胞系MTDC进行鉴定；并用多种细胞因子组合对MTDC及其MTDC(10)克隆进行诱导。结果：CD40、B7.1、MHC class I在MTDC的表达阳性率分别为70%、10%、10%；MTDC不表达CD11c、MHC classⅡ及Ly5.2低表达CD8α；DEC-205这一重要的树突状细胞的表面分子在MTDC及其１４个亚克隆中有不同程度的表达，阳性率分布于5%-58%。MTDC(10)克隆细胞在GM-CSF、IL-4、IFN-γ，anti-CD40 McAb联合作用下，可上调表达MHC classⅠ、MHC classⅡ及B7.1，阳性率分别为96.3%、42.1%、52.6%，高于MTDC被诱导后表达阳性率；并且发现去除４种因子中任何一种因子，均不能上调B7.1的表达，且IFN-γ在MHCⅡ类分子上调表达中起关键作用。结论：MTDC缺乏典型树突状细胞的表达标志及上皮细胞特点，可能为一特殊的胸腺基质细胞系。     

ICAM-1抗体诱导小鼠胸腺上皮细胞分泌IL-6

目的研究胸腺细胞和ＩＣＡＭ－１抗体对胸腺上皮细胞分泌ＩＬ－６的作用。方法用促ＩＬ－６依赖株增殖法检测ＩＬ－６活性，用原位杂交法检测ＩＬ－６ｍＲＮＡ的表达。结果不同的胸腺细胞亚群均能促进ＭＴＥＣ１分泌ＩＬ－６，而且作用无明显差异。ＩＣＡＭ－１抗体能够促进ＭＴＥＣ１分泌ＩＬ－６，其促进作用呈剂量依赖关系。放线菌酮预处理ＭＴＥＣ１以后，ＩＣＡＭ－１抗体和胸腺细胞均不再能促进ＭＴＥＣ１分泌ＩＬ－６。原位杂交证实，经胸腺细胞和ＩＣＡＭ－１抗体活化后，ＭＴＥＣ１表达ＩＬ－６ｍＲＮＡ明显增多，并且表达ＩＬ－６ｍＲＮＡ的ＭＴＥＣ１数量也增多。提示胸腺细胞和ＩＣＡＭ－１抗体能促进ＭＴＥＣ１合成新的蛋白和ｍＲ－ＮＡ。结论胸腺微环境内，胸腺细胞可以通过粘附分子与胸腺上皮细胞相互作用，并可促进胸腺上皮细胞分泌ＩＬ－６。     

The murine T cell line CT6 provides a novel bioassay for interleukin-7

Like interleukin (IL)?2 and IL-4, IL-7 can act as a growth factor for activated T lymphocytes. Upon screening a panel of growth factor-dependent T cell lines, we found that only the cell line CT6 responded to IL-7, indeed as vigorously as to IL-2. Obviously, these findings challenge the validity of previous results on IL-2 production obtained using the CT6 cell line. However, they also demonstrate a novel and sensitive system for the bioassay of IL-7. The ability of the surveyed T cell lines to proliferate to IL-7 corresponded with the expression of IL-7 receptors (IL-7R) on the cell surface. The murine IL-7R on CT6 was shown to bind IL-7 with dual affinity and was visualized as an affinity cross-linked complex of 93 kDa. This IL-7R appears similar to that seen on murine splenic T cells and on 70Z/3, the pre-B cell line from which the murine IL-7R was cloned.     

小鼠白细胞介素-18的cDNA克隆及在真核细胞中初步表达的研究

目的 克隆小鼠白细胞介素－１８（ＩＬ－１８）编码区的ｃＤＮＡ,并实现在真核细胞中的表达。方法 用小鼠白细胞介素 －１８（ｍＩＬ－１８）的ｃＤＮＡ核苷酸序列,设计、合成基因序列特异性引物,应用逆转录多聚酶链反应ＲＴ－ＰＣＲ,以植物血凝（ＰＨＡ）和细胞脂多糖（ＬＰＳ）刺激的小鼠非粘附性脾细胞的ｍＲＮＡ为模板,扩增获得全长ｍＩＬ－１８,转染小鼠成纤维细胞系ＳＶＴ２,并进行ＩＬ－１８生物学活性的检测。结果     

Establishment of a murine thymic epithelial cell line capable of inducing both thymic nurse cell formation and thymocyte apoptosis

A thymic epithelial cell (TEC) line (B/c. TEC-L1) was established from a normal thymus of a 4-week BALB/c mouse. The B/c. TEC-L1 had an epithelial morphology showing a contact-inhibited cobblestone-like arrangement with occasional desmosome-like structures at the adjacent cellular membranes. B/c.TEC-L1 cells showed positive staining for desmosomal glycoprotein, cytokeratin, thymosin alpha 1 beta 3, and I-Ad, and MHC class I antigens. The doubling time was 24 hours, and the chromosome number ranged from 52 to 78 with the mode of 70. Coculture of B/c.TEC-L1 cells with syngeneic, peanut agglutinin-agglutinated (PNA+) thymocytes in suspension at 37 degree C was followed by the formation of TEC thymocyte rosettes, after which the reconstitution of thymic nurse cells ensued. At 4 degrees C, PNA+ thymocytes bound to the B/c.TEC-L1 cell but did not form thymic nurse cells. PNA- thymocytes, although to a lesser degree than PNA+ cells, bound to the TECs at 37 degrees C, but at 4 degrees C few cells bound to the TECs. Allogeneic thymocytes also bound to the TECs at 37 degrees C. When the PNA+ thymocytes were cultured on the B/c.TEC-L1 monolayer, the small ones chiefly adhered on the surface of the TECs, while underneath the TECs the relatively large thymocytes (including cells in mitosis) predominated. Although the PNA- thymocytes bound to the surface of the monolayer within a few hours after coculture, by 24 hours nearly all cells disappeared. It is presumed that the thymocytes creeping underneath the B/c.TEC-L1 monolayer and those enveloped within the thymic nurse cell reconstituted in the suspension culture; both may be placed in circumstances analogous to the thymic microenvironment, wherein immature thymocytes appear to contact TECs directly and to be exposed to higher concentrations of thymic hormones and other soluble factors. Additionally, cell death in the PNA+ thymocytes was also observed in the coculture with B/c.TEC-L1 cells. The PNA+ cells revealed the morphological changes termed "apoptosis" characterized by chromatin condensation and nuclear fragmentation.     

Development of a continuous IL-7-dependent murine pre-B cell line PB-1 suitable for the biological characterisation and assay of human IL-7

Human interleukin-7 (IL-7) is a cytokine that appears to be critical for early T- and B-cell development and although IL-7 is currently under investigation as a therapeutic agent in a variety of hematolymphopoietic disorders, there have been few instances of the detection or investigation of this cytokine using a biological assay. This has been due, in the main, to the lack of a widely available, stable, easy to maintain and use, IL-7 responsive cell line. We have developed a pre-B-cell line, PB-1, from murine bone marrow, that is dependent on IL-7 for growth and has been maintained continually for up to 1 year without loss of responsiveness. The cells survive freezing and reviving, having been stored for periods of up to 4 years. The IL-7 bioassay is reproducible and sensitive, able to reliably detect 50 pg/ml IL-7. The assay is completely unresponsive to any other stimulatory cytokines tested and is not affected by a wide variety of inhibitory cytokines, with the exception of high levels of interferon alpha. The assay can be made completely specific for human IL-7 by including specific neutralizing antibodies for IL-7 and has been shown to be suitable for the estimation of IL-7 in both plasma and serum samples.     

Enhancement of interleukin-1 activity by murine cytomegalovirus infection of a macrophage cell line

The effect of murine cytomegalovirus (MCMV) infection on interleukin 1 (IL-1) secretion was assessed using the macrophage cell lines P388D1 and J774A.1. The former proved to be nonpermissive for MCMV in that infectious virus and viral immediate early protein (pp89) were not expressed in these cells. MCMV infection of the P388D1 cells had no effect on release of biologically active IL-1. In contrast, J774A.1 cells, which were semipermissive for virus replication and pp89 expression, secreted enhanced levels of IL-1 activity following infection. The enhancement was evident when infection either preceded or followed lipopolysaccharide stimulation of the macrophages. The relative proportion of IL-1 alpha and beta secreted from MCMV-infected cells was similar to noninfected controls. In addition, the bioactivity of intracellular IL-1 alpha escaping membranes of fixed cells was unaffected by virus infection. From these findings, we conclude that limited MCMV expression in the J774A.1 macrophage cell line enhances secretion of IL-1 alpha and beta bioactivity.     

Tunicamycin inhibits function and expression of the high-affinity IL-2 receptor in a murine IL-2-dependent cell line.

Murine interleukin-2-dependent T-lymphocytes (CT6) were treated with tunicamycin, an inhibitor of both glycoprotein and ganglioside synthesis, to study the involvement of glycosylation in the IL-2 proliferative response. Tunicamycin inhibited proliferation in a dose-dependent manner at concentrations which did not inhibit protein synthesis (10-50 ng/ml). Swainsonine, a glycoprotein processing inhibitor, had no effect on proliferation. Inhibition of proliferation by tunicamycin was accompanied by an inhibition of binding of 125I-IL-2 to its high-affinity receptor. Scatchard analysis showed that receptor number was decreased by tunicamycin treatment. On the other hand, tunicamycin did not affect either the binding of the monoclonal antibody 7D4, specific for the 55 kDa low-affinity protein subunit of the IL-2 receptor, or the recycling of the IL-2 receptor. To determine the specific effects of tunicamycin on the biosynthesis of particular CT6 glycoconjugates, cells were radiolabeled with 3H-glucosamine and incorporation into ganglioside, neutral glycolipid and glycoprotein fractions was measured. Low doses of tunicamycin inhibited ganglioside synthesis and glycoprotein glycosylation to the same extent, whereas no effect on neutral glycolipid synthesis was observed. These results suggest that glycosylation of glycoprotein and/or gangliosides might play an important role in the formation of a functional high-affinity IL-2 receptor complex in CT6 cells.     

Immunohistochemical studies on the phenotype of murine and human thymic stromal cell lines

Four different murine and human thymic stromal cell (TSC) lines were analyzed by means of indirect immunofluorescence for the presence of tissue specific intermediate filament proteins, extracellular matrix products and thymic hormone. Among these cell lines, only one (IT-45R1) was shown to be epithelial in nature, as revealed by its immunoreactivity with antikeratin antibodies. In addition, IT-45R1 cells (but not the other cell lines) produced thymulin--a well defined thymic hormone--that was detected intracellularly and in the culture medium. Concerning extracellular matrix elements, we noted that all TSC lines were able to produce basement membrane proteins as type IV collagen and fibronectin. Type I collagen however was synthesized by TEPI, HT-5 and HT-7 cells but not by IT-45R1 cells. Our data demonstrate that only the IT-45R1 TSC line is epithelial and active in thymic hormone production. The other three TSC lines are not epithelial in nature, but their definitive phenotypes remain to be determined.     

Constitutive interleukin 2 production by the JURKAT human leukemic T cell line

Interleukin 2 (IL2) is a lymphokine produced from phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells and characterized biologically by its ability to maintain the in vitro proliferation of activated T cells. In a search for a convenient alternative source of biologically active human IL2, cells from the five established T cell lines, MOLT4, HSB2, CCRF-CEM, RPMI1301 and JURKAT were cultured at high concentrations for 18-36 h (induction cultures), and their cell-free supernatants thereafter screened on IL 2-dependent cultured human and mouse T cells. MOLT4, HSB2, RPMI1301, and CCRF-CEM all failed to produce detectable levels of IL2. Of the three JURKAT cell lines obtained from different sources, one, designated JMN, produced high levels of IL2 activity. A second, JM, failed to produce any IL2, while the third, JHAN, produced intermediate levels. Stimulation of the IL2-producing JMN or JHAN variants with PHA, the phorbol diester 12-0-tetradecanoyl-phorbol-13-acetate (TPA), or both PHA and TPA together, resulted in an apparent increase of IL2 activity in the culture supernatant when assayed by a short-term tritiated thymidine incorporation test. However, both PHA and TPA added directly to the test cells caused substantial thymidine incorporation. Moreover, the nonproducer line JURKAT-JM could not be converted to an IL2 producer by stimulation with PHA, TPA, or both. When JMN supernatants were used to support actual long-term growth and cloning of T cells in limiting dilution, the constitutively produced IL2 was superior to that produced after PHA and/or TPA stimulation. Addition of TPA, but not of PHA, to lectin and TPA-free JMN IL2 resulted in a decreased ability of such supernatants to support clonal T cell growth, suggesting that TPA had a growth-inhibiting effect. These results show that the continuously growing JURKAT-JMN cell line could provide a suitable source of mitogen-free human IL2.     

Triptolide suppresses T-lymphocyte proliferation by inhibiting interleukin-2 receptor expression,but spares interleukin-2 production and mRNA expression

The purpose of this study was to elucidate the mechanism of action of triptolide on the T-lymphocyte-mediated immune response. Lymphocytes were incubated with a suboptimal dose oof Con A or PHA in the presence or absence of varying doses of triptolide to assess the effect of triptolide on lymphocyte proliferation, interleukin-2(IL-2) production and IL-2 receptor expression. Then, Con A or PHA induced T-blast cells were cultured with a sufficient dose of recombinant human IL-2 in the presence or absence of triptolide to evaluate the effect of triptolide on the interaction of IL-2 and IL-2 receptors. The effect of triptolide on the immune response in vivo was also investigated. The results of these studies clearly demonstrated that triptolide selectively inhibited the T-lymphocyte proliferative response to Con A and PHA, but had less effect on LPS-induced B-lymphocyte proliferation. Triptolide also suppressed the expression of IL-2 receptors on PHA induced T-blast cells, but did not alter the production of IL-2 by mouse splenic cells and human tonsil lymphocytes. Furthermore, the results also showed that triptolide at higher concentration had a slight inhibitory effect on the interaction of IL-2 and IL-2 receptors, and addition of exogenous IL-2 did not reverse the inhibiting action of triptolide on T-cell proliferation. Taken together, these results suggest that triptolide inhibits T-lymphocyte proliferation mainly by affecting IL-2 receptor expression rather than IL-2 production.     

IL—6诱导人骨髓瘤细胞表达CD45

目的：研究髓瘤细胞系Sko-007中IL－6信号途径活化与CD45诱导表达之间的关系。方法：首先采用凝胶阻滞电泳（electrophoretic mobility shift assay,EMSA)方法检测参与IL－6信号转导功能的转录因子STAT3和NF－IL－6在Sko-007细胞中的诱导活化情况并确定该细胞中IL－6信号转导途径;进而采用RT－PCR和FACS方法检测CD45mRNA和蛋白在IL－6刺激作用下的诱导表达情况;最后采用以上两种方法观察CD45诱导表达与I－6信号途径活化之间的关系。结果：①两种主要的IL－6信号转导途径JAK／STAT和Ras/NF-IL-6都能够在Sko-007细胞中诱导激活;②CD45mRNA和蛋白的表达量在IL－6刺激作用下明显增加;③STAT3反义表达质粒导入Sko-007细胞后JAK／STAT途径活化信号减弱,同时CD45mRNA诱导表达量下降。结论：Sko－007细胞中JAK／STAT途径的诱导激活介导了CD45的诱导表达。     

胸腺细胞对胸腺止皮细胞分泌IL-6的促进作用

为分析胸腺细胞对胸腺基质细胞功能的调节作用，将胸腺细胞与小鼠胸腺上皮细胞系（ＭＴＥＣ１）共育，分析胸腺细胞对ＭＴＥＣ１分泌ＩＬ－６的影响。结果表明，胸腺细胞能明显促进ＭＴＥＣ１分泌ＩＬ－６，其促进程度与两种细胞的数量及共育时间有关。胸腺细胞（４×１０~６／孔）与ＭＴＥＣ１（１×１０~５／孔）共育４８小时，ＭＴＥＣ１分泌ＩＬ－６达高峰。去除胸腺细胞后９６小时，ＭＴＥＣ１分泌ＩＬ－６的量仍比单独培养的ＭＴＥＣＩ多１．７倍。经丝裂霉素Ｃ处理的胞腺细胞仍能促进ＭＴＥＣ１分泌ＩＬ－６，其作用程度与末经处理的胸腺细胞相似。而胸腺细胞培养上清及裂解液则不影响ＭＴＥＣ１分泌ＩＬ－６，从而证实胸腺细胞能促进ＭＴＥＣＩ分泌ＩＬ－６，其作用机制可能与细胞-细胞直接相互作用有关。     

Generation and characterization of stromal cell independent IL-7 dependent B cell lines

In-vitro B cell cultures have played a significant role in the study of B cell development. Their utility in developmental and biochemical studies, however, has been limited by the challenges associated with obtaining and maintaining adequate cell numbers of pure and/or rare populations. Although B cell lines allow for circumvention of some of these issues, they have traditionally been generated via viral infection or genetic transformation and are thus less representative of in-vivo cells. In order to avoid such alterations in cell state, we have designed a procedure for the creation of B cell lines directly from murine bone marrow. In this study, we describe the generation and characterization of these IL-7 dependent cell lines. Our lines, established from both wild type and mutant mice, do not require stromal cell support for generation or maintenance. In addition, clones survive repeated freeze/thaw cycles and, in the presence of IL-7, can be kept in culture indefinitely. Phenotypically, our lines resemble pro/pre-B cells and exhibit IL-7 and preBCR signaling profiles that mimic ex-vivo B cells. These lines promise to be useful in the study of the signaling pathways that regulate B cell development.     

Proliferation and differentiation of immature thymocytes induced by a thymic stromal cell clone

The monolayer of our established thymic stromal cell clone (MRL104.8a) exhibited the capacity to maintain immature double-negative thymocytes. Such capacity was also expressed by a factor produced by the MRL104.8a monolayer. This factor designated as thymic stroma-derived T cell growth factor (TSTGF) was found to be distinct from IL-2 or IL-4 but similar to IL-7 of the previously described cytokines from the functional and molecular aspects. The MRL104.8a monolayer also exerted its differentiation-promoting effect on double-negative thymocytes. Culture for one day of purified double-negative thymocytes on the monolayer resulted in the induction of an appreciable per cent of CD3-4-8+ cells. This differentiation could also be induced by a semipurified TSTGF sample but not by recombinant IL-7, suggesting that the MRL104.8a cells elaborate a factor(s) responsible for initiating the differentiation of double-negative cells in addition to the growth-promotion factor identical or closely related to IL-7. When the culture period of double-negative thymocytes was extended to 2 or 3 days, an appreciable number of double-positive (CD4+8+) and single-positive (CD4+8-) cells were generated on the MRL104.8a monolayer. Thus, these observations provide strong support for the proposition that a specialized thymic stromal component plays an essential role in the intrathymic T cell development in the context of T cell growth and differentiation.     

骨髓基质细胞系BMSC1自发分泌多种细胞因子

骨髓基质细胞（ＢＭＳＣ）及其分泌的细胞因子在造血细胞分化发育过程中起重要作用。应用特异性细胞因子依赖株检测了自建的小鼠骨髓基质细胞株ＢＭＳＣ１的细胞因子分泌情况。实验说明ＢＭ－ＳＣ１细胞能自发分泌高水平的ＩＬ－６，中等水平的ＩＬ－７及较低水平的ＧＭ－ＣＳＦ，未检测到化学趋化因子。此细胞上清对骨髓造血干细胞有明显的促集落形成效应，所形成的集落以ＣＦＵ－ＧＭＭ及ＣＦＵ－ＧＭ为主，其促集落形成作用呈现剂量依赖关系。上述结果表明，骨髓基质细胞能够产生多种类型的细胞因子从而对于细胞骨髓内分化发育成Ｐｒｏ－Ｔ细胞可能起重要作用。