ATL and HTLV-I:In vivo cell growth of ATL cells

The mechanism of leukemogenesis or neoplastic cell growth in adult T cell leukemia (ATL) still remains unclear, although Tax of human T cell leukemia/lymphoma virus type I (HTLV-I), the etiologic virus, has been reported to affect the expression of various cellular genes which encode molecules involved in cell growth or cell death. We have studied the cell growth of HTLV-I-infected human T cells in severe combined immunodeficiency (SCID) mice and found that fresh leukemic cells or cell lines derived from leukemic cell clones but not HTLV-I-infected cell lines of nonleukemic cell origin showed tumorigenicity, and neither HTLV-I nor IL-2 expression was needed for cell growthin vivo, indicating that accumulating changes in addition to the initial events induced by HTLV-I infection were required for the development of ATL. The interaction between ATL cells and vascular endothelial cells appears to be one of the important factors which determine the pattern of organ infiltration by leukemic cells. E-selectin and its ligand are one of the major cell adhesion pathways between ATL cells and human umbilical vein endothelial cells (HUVEC). Another pathway that had not been identified was studied using newly developed monoclonal antibodies capable of blocking cell adhesion. The molecules which directly mediate adhesion between ATL cells and HUVEC were determined to be OX40 and gp34, a member of the tumor necrosis factor receptor (TNF-R) family and TNF family, respectively. The OX40/gp34 system may play a key role in the trafficking and homing of not only ATL cells but also activated normal T cells.     

Immature B cells from human and mouse bone marrow can change their surface light chain expression

The capacity of bone marrow-derived surface immunoglobulin-positive (sIg⁺) human and mouse immature B cells, generated either in vitro or in vivo, to change their light (L) chain expression, has been assayed by the number of cells which change in vitro from one type of L chain to the other type, or to no sIg at all. Immature sIg⁺ B cells were generated in vitro from sIg^? precursor cells from human or mouse bone marrow. The immature sIg⁺ cells expressed RAG-1. Human sIg⁺ cells expressed xfr; and λ L chains in ratios between 1:1 and 3:1, whereas in mouse cells, this ratio ranged from 10:1 to 20:1. Upon reculture of the human and mouse xfr;⁺sIg⁺ cells, about half of them remained xfr;⁺, a quarter became λ⁺, and another quarter became sIg^?. Between 1 and 3% expressed both xfr; and λ chains. Of the human λ⁺ cells, about two-thirds remained λ⁺, only 1 to 2% became xfr;⁺, while the other third became sIg^?. Again, between 1 and 3% expressed both xfr; and λ L chains. These results indicate that expression of sIgM in the B cell membrane does not terminate L chain gene rearrangement, and that some order exists in xfr; versus λ gene rearrangements. Hence, human and mouse xfr;⁺ immature B cells can become λ⁺, but very few of the λ⁺ cells can become xfr;⁺, and both can become sIg^?. Further, human CD10⁺/sIg⁺ xfr;⁺ and λ⁺ cells and mouse B220^low/sIg^low xfr;⁺ cells enriched from bone marrow, i.e. immature B cells differentiated in vivo, changed their Ig phenotype upon in vitro culture, but in lower frequencies. By contrast, human and mouse mature B cells did not change their L chain or Ig phenotype. Hence, at least a part of the sIg⁺ immature B cells in bone marrow retain the capacity to change their L chain and Ig phenotype, and this capacity is lost when they become mature, peripheral B cells.     

Fine structure of the anteromedial eye of the liphistiid spider,Heptathela kimurai

Background: The presence of efferent fibers in the anteromedial eye of liphistiid spiders kept in natural daily cycles of illuminance has been reported. However, this report is limited to innervation by the efferent fiber and daily rhabdomal changes, and there have been no detailed ultrastructural accounts of the eye. Methods: The fine structure of this eye was examined by electron microscopy. Results and conclusions: The eye consists of a cornea, a lens, a vitreous body, and a retina. The retina contains 13 or 14 receptor cells and glial cells. The rhabdoms are distal to the nuclei of the receptor cells. In the distal region of the receptive segment, the rhabdomeres lie in the center of the cell. In the middle region, anisomorphic rhabdoms formed by microvilli from adjacent cells are at the cell periphery. In the proximal region, the rhabdomeres are situated in the center of the cell. The ocellar nerve of the eye runs toward the protocerebrum and enters the posterior part of the first optic ganglion of the secondary eyes. Pigmented cells and nonpigmented cells are observed. The pigmented cells are located in the most lateral of the eye and cover the whole eye. The nonpigmented cells are located in the receptor cell bodies and extend to the origin of the ocellar nerve. They wind to form capillaries filled with electron-dense material. These structures are discussed in comparison with those of other spiders and other chelicerates. © 1994 Wiley-Liss, Inc.     

Small CD4+8+TCRlow thymocytes contain precursors of mature T cells

To evaluate directly the developmental potential of cortical CD4⁺8⁺ thymocytes, highly purified populations of small, nondividing CD4⁺8⁺TCR^low and large, dividing CD4⁺8⁺TCR^high thymocytes from H-2^d mice expressing a transgenic T cell receptor restricted by H-2D^b (major histocompatibility complex class I) molecules were transferred into the thymus of normal, nonirradiated H-2^b recipient mice. The results show that both populations generate CD4^?8⁺ thymocytes under these conditions, thus providing conclusive evidence that small cortical thymocytes do not represent a “dead end” but an important intermediate stage in T cell development.     

Tonic rhythmic activity of rat cerebellar neurons

Simultaneous recordings of multiple single unit activity in both cerebral and cerebellar cortex, cortical EEG, and both nuchal and vibrissal EMG were obtained in nine unrestrained rats. Putative Purkinje cells of the deep vermal cerebellar cortex exhibited rhythmic discharge of simple spikes with extremely low variability in interspike intervals for several hours. The highly rhythmic nature of spike discharge was remarkably stable across all states of sleep (both slow-wave and rapid eye movement sleep) and wake including quiet waking, grooming, eating, running in a familiar environment, and exploring a novel environment. The frequencies at which oscillatory discharges took place varied, among different cells, between 16 and 142 Hz; however, 75% of the recorded cells discharged at frequencies between 20 and 50 Hz. From recordings in which two to four such cells were recorded simultaneously, evidence was found for multiple cells firing at the same frequency as well as for multiple cells firing at different frequencies. The precise timing of spike discharge in these cells makes them potential candidates to participate in timing functions thought to depend on the cerebellum     

CD4+CD25+T细胞的扩增方法与临床应用

CD4+CD25+T细胞是最重要的一类调节性T细胞(Tr).体内固有CD4+CD25+T细胞的自然扩增率极低,不能满足临床治疗的需要.通过采用FoxP3基因转染技术、阻断细胞活化信号、DC诱导、加入细胞因子等方法,对CD4+CD25+T细胞的数量和功能进行扩增,使其在器官移植、自身免疫性疾病和肿瘤免疫等领域具有广泛的临床应用前景.     

人Flt3配体基因的克隆及其在CHO细胞中的表达

目的克隆人Flt3配体（Flt3 LIg and，FL），并在CHO细胞中进行表达。方法从健康人外周血中提取总RNA，通过RT-PCR技术，扩增Flt3配体胞外区cDNA功能性片段，经DNA测序证实后，将得到的片段基因插入pcDNA3．0表达载体，构建了pcDNA3．0-FL真核表达载体；将重组质粒pcDNA3．0-FL转染CHO细胞．经G418筛选出阳性细胞克隆，扩大培养，提取细胞总蛋白，用SDS—PAGE分离并Western blotting检测到在相对分子质量约24000处有一显色条带。结果FL胞外区cDNA被正确克隆到真核表达载体pcDNA3．0中并在CHO细胞中成功表达。结论成功构建了真核表达载体pcDNA3．0-FL并在CHO细胞中成功表达，为FL的相关研究和应用开发奠定了基础。     

14-3-3σ调控p27抑制Rat1-Akt细胞增殖

目的： 研究腺病毒介导14-3-3·σ（Ad-14-3-3·σ）对Akt过表达Rat1-Akt细胞增殖的影响，并探讨其作用是否通过调控p27而实现。 方法： 通过5-溴-2′脱氧尿嘧啶（BrdU）实验检测Ad-14-3-3·σ对Rat1-Akt细胞增殖的影响，并通过激酶分析法和免疫荧光实验探讨Ad-14-3-3·σ对p27磷酸化水平及其在细胞内定位的影响。 结果： Ad-14-3-3σ转染的细胞BrdU阳性率（45%）低于PBS处理组（100%）或Ad-β-gal转染的对照组细胞（98%）。14-3-3σ可降低磷酸化p27的水平和减少Akt介导的p27在胞浆中的定位。 结论： 转染14-3-3σ基因能抑制Akt过表达细胞株Rat1-Akt增殖，14-3-3σ通过降低Akt激酶磷酸化p27的活性，阻断Akt介导的p27胞浆错位，从而发挥其抑制Rat1-Akt细胞增殖。     

氧化修饰低密度脂蛋白可诱导人单核细胞源树突状细胞形成泡沫细胞

目的： 探讨氧化修饰低密度脂蛋白（ox-LDL）对人单核细胞源树突状细胞（DC）功能的影响。 方法： 采用免疫磁珠法分离人外周血CD14+单核细胞，经含rhGM-CSF（100 μg/L）和rhIL-4（20 μg/L）的Cellgro培养，使其分化为DC。DC与100 mg/L天然的或氧化修饰的LDL孵育72 h后，采用透射电镜和尼罗红染色观察细胞内脂质沉积，流式细胞术检测DC表型（CD1a，CD40，CD86，HLA-DR），混合T淋巴细胞反应检测DC对淋巴细胞增殖的影响，FITC-dextran检测DC吞噬功能，ELISA检测细胞培养上清Th1/Th2 (IL-12/IL-2)细胞因子的浓度。 结果： ox-LDL可诱导DC形成泡沫细胞，而天然的LDL无此作用。经ox-LDL处理的DC吞噬作用明显弱于天然的LDL，而对T细胞增殖作用却明显强于天然的LDL；可明显上调CD80(72.4±9.6 vs 89.5±10.1, P<0.01), CD86(67.2±8.8 vs 80.2±11.6, P＜0.01), HLA-DR(80.6±9.8 vs 86.6±10.8, P<0.01) 和CD1a(40.2±10.3 vs 60.2±9.3, P<0.01)的表达，明显促进DC细胞因子IL-12［(44.3±8.9)ng/L vs (65.1±10.4)ng/L, P<0.05］的分泌，但却降低IL-2［(43.6±7.8）ng/L vs （10.0±4.5）ng/L, P<0.01］。 结论： DC可通过摄取ox-LDL形成泡沫细胞，而后者与成熟DC的功能相似，说明DC可能是泡沫细胞新的来源，在动脉粥样硬化免疫病理发生中具有重要的作用。