血管免疫母细胞淋巴结病与胸腺幼稚T淋巴细胞关系的观察

本文运用荧光原位杂交（ＦＩＳＨ）技术结合淋巴细胞免疫表型分型方法,检测了血管免疫母细胞淋巴结病（ＡＩＬＤ）中含有特征性＋３细胞的免疫表型特征、细胞先经ＣＤ４和ＣＤ８免疫分型,再用３号染色体着丝粒异性的ＤＮＡ探针作原位杂交。结果发现含有＋３的细胞ＣＤ４和ＣＤ８阳性,即外周辅助性Ｔ细胞和抑制性Ｔ细胞均含有＋３,说咀＋３的畸变发生于胸腺中处于中期分化阶段的普通胸腺细胞,从而推测ＡＩＬＤ可能起源于胸腺幼稚的Ｔ细胞。     

IL－7对早期胸腺细胞发育的作用

胸腺基质细胞分泌白细胞介素７（ＩＬ－７）。ＩＬ－７是早期Ｔ细胞的重要生长因子之一。它能选择性促进ＣＤ４－ＣＤ８－和ＣＤ４＋ＣＤ８－／ＣＤ４－ＣＤ８＋细胞增殖。ＩＬ－７主要维持早期前体Ｔ细胞存活,同时保持其Ｔ前体细胞潜能。ＩＬ－７对胸腺细胞分化的作用目前仍有争议。     

IL—7对早期胸腺细胞发育的作用

胸腺基质细胞分泌白细胞介素７（ＩＬ－７）。ＩＬ－７是早期Ｔ细胞的重要生长因子之一。它能选择性促进ＣＤ４＾－ＣＤ８＾－和ＣＤ４＾＋ＣＤ８＾－／ＣＤ４＾－ＣＤ８＾＋细胞增殖。ＩＬ－７主要维持早期前体Ｔ细胞存活,同时保持其Ｔ前体细胞潜能。ＩＬ－７结胸腺细胞分化的作用目前仍有争议。     

衰老对小鼠胸腺细胞表面抗原表达的影响

采用流式细胞计技术和胚胎胸腺器官体外培养实验研究不同年龄小鼠胸腺细胞的发育。结果表明,随着小鼠年龄的增长,胸腺细胞的细胞表型由Ｐｇｐ－１高向Ｐｇｐ－１低下调表达受阻;老年组小鼠胸腺与幼年组小鼠胸腺相比,含有较多的ＣＤ４和ＣＤ８双阴性细胞和Ｐｇｐ－１阳性细胞,较少ＣＤ４和ＣＤ８双阳性细胞和ＭＥＬ－１４阳性细胞。     

p56^lck与T细胞发育

ｐ５６~（ｌｃｋ）与Ｔ细胞发育田兰,陈慰峰（北京医科大学免疫系１０００８３）来源于骨髓的多能干细胞在胸腺内经过一系列复杂的发育过程成为功能成熟的Ｔ细胞。根据细胞表面ＣＤ４、ＣＤ８分子的表达,可将胸腺细胞分为４个不同的亚群,其发育顺序为ＣＤ４－ＣＤＳ－...     

人体胸腺和周围淋巴器官内T细胞亚群和NK细胞分布的研究

本文用多种Ｔ细胞和ＮＫ细胞单抗和免疫组织化学的ＡＢＣ技术,在冰冻切片上对人扁桃体、淋巴结、牌和胸腺内Ｔ细胞亚群和ＮＫ细胞的分布进行了检测。结果显示,ＣＤ５、ＣＤ８、ＣＤ４、ＣＤ３和ＡＩＧ３阳性细胞主要分布在扁桃体,淋巴结的副皮质区、脾的动脉周围淋巴鞘和胸腺,但各种抗体的反应强度不同。从各种Ｔ细胞工群的染色强度和形状看,胸腺髓质部的胸腺细胞相当于周围淋巴器官内的胸腺依赖区。胸腺内Ｔ细胞在分化过程中,质膜上的抗原也有相应变化。ＮＫ细胞主要分布在淋巴小结的生发中心,淋巴结和扁桃体的副皮质区,脾的红髓以及胸腺的筋质部。这些不同的分布,说明ＮＫ细胞不仅与淋巴小结的活动有关,可能还参与机体的免疫调节功能。     

重组人胸腺素α原体外活性观察

以原核表达并纯化人胸腺素α原后,观察其体外活性,了解到胸腺素α原对胸腺细胞氢化考的松损伤有明显的保护作用,表现在它可明显提高氢化考的松损伤后细胞的数目和ＭＴＴ反应能力,氢化考的松引起胸腺细胞凋亡的发生,并显著降低ＣＤ４＋、ＣＤ８＋单阳性细胞和ＣＤ４－ＣＤ８－双阴性细胞的比例,胸腺素α原不能抑制胸腺细胞凋亡的发生,并可能对胸腺细胞凋亡有促进作用,与空白对照组比较,它也可明显降低ＣＤ４＋阳性细胞的比例,结果表明,胸腺素α原对胸腺细胞氢化考的松损伤的保护作用并非通过抑制凋亡而实现。     

半导体激光血管内照射对人体外周血T淋巴细胞亚群及NK细胞…

本文报道了半导体激光血管内照射对人体外周血Ｔ淋巴细胞亚群及ＮＫ细胞的免疫调节作用。实验结果提示：在２３例经６５０ｎｍ．５ｍＷ的半导体激光血管内照射治疗一次,五次和十次的患者中,ＣＤ＾＋３细胞亚群的百分比与照射前（６３．６６％）比较,分别提到６５．８６％,６９．９４％,７５．０４％。ＣＤ＾＋４Ｔ辅助细胞在第十次治疗后也有所增加。除此之外,半导体激光血管内照射对ＮＫ细胞比例及ＣＤ＾＋４／ＣＤ＾＋８比值     

半导体激光血管内照射对人体外周血T淋巴细胞亚群及NK细胞的调节作用

本文报道了半导体激光血管内照射对人体外周血Ｔ淋巴细胞亚群及ＮＫ细胞的免疫调节作用。实验结果提示：在２３例经６５０ｎｍ．５ｍＷ的半导体激光血管内照射治疗一次,五次和十次的患者中,ＣＤ＋３细胞亚群的百分比与照射前（６３．６６％）比较,分别提高到６５．８６％,６９．９４％,７５．０４％。ＣＤ＋４Ｔ辅助细胞在第十次治疗后也有所增加。除此之外,半导体激光血管内照射对ＮＫ细胞比例及ＣＤ＋４／ＣＤ＋８比值具有双向调控作用,即偏离（即高于或低于）正常值的患者经照射后恢复到正常水平。这种双向调控作用将对临床治疗更有指导意义。     

轮状病毒肠炎患儿T细胞和红细胞免疫功能动态观察

报道４０例轮状病毒肠炎患儿急性期和恢复期外周血Ｔ细胞亚群和红细胞免疫功能的变化,并与同龄正常儿童进行了比较。结果表明急性期患儿ＣＤ３、ＣＤ４细胞及ＣＤ４／ＣＤ８比值均明显降低,ＣＤ８不变,至恢复期随着临床症状的改善,ＣＤ３、ＣＤ４及ＣＤ４／ＣＤ８逐渐正常。轮状病毒肠炎患儿急性期红细胞Ｃ３ｂ受体花环率显著下降,恢复期接近正常。结果提示细胞免疫参与了轮状病毒肠炎的感染过程,ＣＤ４／ＣＤ８与该病的预后有关。轮状病毒肠炎急性期可有继发性红细胞免疫功能下降,治疗时,有必要维持患儿的红细胞免疫功能,以提高其抗感染能力     

Cytokine production by mature and immature CD4-CD8- T cells. Alpha beta-T cell receptor+ CD4-CD8- T cells produce IL-4.

This study follows our previous investigation describing the production of four cytokines (IL-2, IL-4, IFN-gamma, and TNF-alpha) by subsets of thymocytes defined by the expression of CD3, 4, 8, and 25. Here we investigate in greater detail subpopulations of CD4-CD8- double negative (DN) thymocytes. First we divided immature CD25-CD4-CD8-CD3- (CD25- triple negative) (TN) thymocytes into CD44+ and CD44- subsets. The CD44+ population includes very immature precursor T cells and produced high titers of IL-2, TNF-alpha, and IFN-gamma upon activation with calcium ionophore and phorbol ester. In contrast, the CD44- subset of CD25- TN thymocytes did not produce any of the cytokines studied under similar activation conditions. This observation indicates that the latter subset, which differentiates spontaneously in vitro into CD4+CD8+, already resembles CD4+CD8+ thymocytes (which do not produce any of the tested cytokines). We also subdivided the more mature CD3+ DN thymocytes into TCR-alpha beta- and TCR-gamma delta-bearing subsets. These cells produced cytokines upon activation with solid phase anti-CD3 mAb. gamma delta TCR+ DN thymocytes produced IL-2, IFN-gamma and TNF-alpha, whereas alpha beta TCR+ DN thymocytes produced IL-4, IFN-gamma, and TNF-alpha but not IL-2. We then studied alpha beta TCR+ DN T cells isolated from the spleen and found a similar cytokine production profile. Furthermore, splenic alpha beta TCR+ DN cells showed a TCR V beta gene expression profile reminiscent of alpha beta TCR+ DN thymocytes (predominant use of V beta 8.2). These observations suggest that at least some alpha beta TCR+ DN splenocytes are derived from alpha beta TCR+ DN thymocytes and also raises the possibility that these cells may play a role in the development of Th2 responses through their production of IL-4.     

IL-7 maintains the T cell precursor potential of CD3-CD4-CD8- thymocytes.

We and other investigators have reported that IL-4 (in the presence of PMA) or IL-7 (used alone) induce proliferation of both adult and fetal (gestation day 15) CD4-CD8- thymocytes. These results suggested that these cytokines may be growth factors for pre-T cells. However, we recently observed that among adult CD4-CD8- thymocytes, only the CD3+ subset proliferates in response to IL-7, whereas IL-4 + PMA induces proliferative responses in both CD3- and CD3+ subsets. Thus, we concluded that IL-7 used alone is not a potent growth stimulus for adult thymic CD3-CD4-CD8- triple negative (TN) T cell precursors. Interestingly, the viability of adult TN thymocytes in culture was improved by IL-7 for up to 1 wk, in spite of the inability of IL-7 to induce significant [3H]TdR incorporation in these cells. After culture in IL-7 for 4 days, the viable cells remained CD4-CD8-, but 25 to 35% expressed CD3 whereas the rest remained CD3-. In contrast, most of the cells cultured with IL-4 + PMA for 4 days remained TN. To investigate whether adult TN thymocytes that survive in vitro in the presence of IL-4 + PMA or IL-7 retain T cell progenitor potential, we tested whether they could reconstitute lymphoid cell-depleted (2-deoxyguanosine-treated) fetal thymus organ cultures. Our results demonstrate that TN cells cultured in IL-7 retain T cell progenitor potential.     

Selective support of a mouse thymus epithelial cell line （MTEC1） to the viability and proliferation of CD4＋CD8—,CD4^—CD8^—,and CD4^＋CD8^＋thymocytes in vitro

The MTEC1 cell line,established in our laboratory,is a normal epithelial cell line derived from thymus medulla of Balb/c mice and these cells constituteively produce multiple cytokines.The selection of thymic microenvironment on developing T cells was investigated in an in vitro system.Unseparated fresh thymocytes from Balb/c mice were cocultured with MTEC1 cells or/and MTEC1-SN,then,the viability,proliferation and phenotypes of cultured thymocytes were assessed.Without any exogenous stimulus,both MTEC1 cells and MTEC1-SN were able to maintain the viability of thymocytes,while only the MTEC1 cells,not the MTEC1-SN,could directly activate thymocytes to exhibit moderate proliferation,indicating that the proliferative signal is delivered through cell surface interatcions of MTEC1 cells and thymocytes.Phenotype analysis on FACS of viable thymocytes after coculture revealed that MTEC1 cells preferentially activate the subsets of CD4^ CD8^-,CD4^ CD^8 and CD^4- CD^8- thymocytes;whereas MTEC1-SN preferentially maintained the viability of CD4^ CD^8- and CD4^-CD8^ thymocyte subsets.For the Con A-activated thymocytes.both MTEC1 cells and MTEC1-SN provided accessory signal(s) to significantly increase the number of viable cells and to markedly enhance the proliferation of thymocytes with virtually equal potency,phenotyped as CD4^ CD8^-,CD4^-CD8^ ,and CD^4-CD8^-subests,In summary,MTEC1 cells displayed Selection of thymic epithelial cells on thymocyte subsets. selective support to the different thymocyte subsets,and the selectivity is dependent on the status of thymocytes.     

Thymic shared antigen-2: a novel cell surface marker associated with T cell differentiation and activation

Thymic shared Ag-2 (TSA-2) is a 28-kDa, glycophosphatidylinitosol-linked cell surface molecule expressed on various T cell and thymic stromal cell subsets. It is expressed on most CD3-CD4-CD8-, CD4+CD8+, and CD3highCD4-CD8+ thymocytes but is down-regulated on approximately 40% of CD3highCD4+CD8- thymocytes. Expression on peripheral TCR-alphabeta+ T cells is similar to that of CD3+ thymocytes, although a transient down-regulation occurs with cell activation. Consistent with the recent hypothesis that emigration from the thymus is an active process, recent thymic emigrants are primarily TSA-2-/low. TSA-2 expression reveals heterogeneity among subpopulations of CD3highCD4+CD8- thymocytes and TCR-gamma delta+ T cell previously regarded as homogenous. The functional importance of TSA-2 was illustrated by the severe block in T cell differentiation caused by adding purified anti-TSA-2 mAb to reconstituted fetal thymic organ culture. While each CD25/CD44-defined triple-negative subset was present, differentiation beyond the TN stage was essentially absent, and cell numbers of all subsets were significantly below those of control cultures. Cross-linking TSA-2 on thymocytes caused a significant Ca2+ influx but no increase in apoptosis, unless anti-TSA-2 was used in conjunction with suboptimal anti-CD3 mAb. Similar treatment of mature TSA-2+ T cells had no effect on cell survival or proliferation. This study reveals TSA-2 to be a functionally important molecule in T cell development and a novel indicator of heterogeneity among a variety of developing and mature T cell populations.     

8B4/20, a private CD43 epitope on developing human thymocytes, is involved in thymocyte maturation

The 8B4/20 Ag is a 120-kDa molecule whose expression on human thymocytes varies according to the differentiation stage: high density on immature CD3-/low thymocytes, reduced density on CD3medium and double-positive thymocytes, and absent on CD3high and single-positive thymocytes and on circulating T cells. In this paper we present immunological and biochemical evidence demonstrating that 8B4/20 Ag is a variant of CD43. We show that 8B4/20-expressing molecules, which are a subset of the CD43 molecules on thymocytes, are heterogeneous in charge, suggesting varying sialylation levels. The 8B4/20 epitope was mapped to the peripherally exposed N-terminal region of CD43, and the 8B4/20 antigenic determinant was characterized by requirement for the sialic acid exocyclic polyhydroxyl side chain, a feature shared with ligands of CD22. Altogether, 8B4/20-CD43 expression pattern and biochemical characteristics suggest its participation in carbohydrate-based interactions in the thymus. We therefore used specific Ab to mimic putative 8B4/20 interactions with natural ligand and examined the effect on isolated thymocytes. Treatment with 8B4/20 had no effect on in vitro apoptosis of isolated thymocytes. In contrast, 8B4/20 ligation enhanced the conversion of isolated thymocytes to differentiated phenotypes. Increased numbers were found in 8B4/20-treated cultures of CD3high and single-positive thymocytes and decreased numbers of CD3-/low and double-positive thymocytes, strongly suggesting that engagement of 8B4/20 delivers a positive signal that favors completion of the thymocyte maturation program. The ability of 8B4/20 mAb to drive thymocyte maturation in vitro suggests that CD43 molecules bearing the 8B4/20 epitope participate in early events of thymic selection.     

The stem cell antigens Sca-1 and Sca-2 subdivide thymic and peripheral T lymphocytes into unique subsets

Stem cell Ag 1 and 2 (Sca-1 and Sca-2), so named due to their expression by mouse bone marrow stem cells, were evaluated for expression by populations of cells within the thymus. Immunohistochemical analysis demonstrated that Sca-1 was expressed by cells in the thymic medulla and by some subcapsular blast cells, as well as by the thymic blood vessels and capsule. Sca-2 expression, which was limited to the thymic cortex, could be associated with large cycling thymic blast cells. Both Sca-1 and Sca-2 were expressed on a sub-population of CD4-CD8- thymocytes, and this subpopulation was entirely contained within the Ly-1lo progenitor fraction of cells. Sca-1 expression by a phenotypically mature subset of CD4+CD8- thymocytes was also noted. Conversely, Sca-2 expression was observed on a phenotypically immature or nonmature subpopulation of CD4-CD8- thymocytes. MEL-14, an antibody that defines functional expression of a lymphocyte homing molecule, identified a small population of thymocytes that contained all four major thymic subsets. Sca-2 split the MEL-14hi thymocyte subset into two Sca-2+ non-mature/immature phenotype fractions and two Sca-2- mature phenotype fractions. In peripheral lymphoid organs, Sca-1 identified a sub-population of mature T lymphocytes that is predominantly CD4+CD8-, in agreement with the thymic distribution of Sca-1. Peripheral T cells of the CD4-CD8+ phenotype were predominantly Sca-1-. In contrast, Sca-2 did not appear to stain peripheral T lymphocytes, but recognized only a subset of B lymphocytes which could be localized by immunohistochemistry to germinal centers. Thus, expression of Sca-1 is observed throughout T cell ontogeny, whereas Sca-2 is expressed by some subsets of thymocytes, including at least one half of thymic blasts, but not by mature peripheral T lymphocytes.     

T cell antigen receptor expression by subsets of Ly-2-L3T4- (CD8-CD4-) thymocytes

The V beta 8-specific mAb F23.1 and KJ16 were used as fluorescent stains to test for TCR expression on the surface of subpopulations of early, CD4-CD8- (L3T4-Ly-2-) thymocytes from adult CBA mice. A surprisingly high proportion (27%) of Ly-2-L3T4- thymocytes were strongly F23.1 and KJ16 positive. No positive cells were detected among Ly-2-L3T4- thymocytes from V beta 8-negative SJL mice. In contrast to the adult thymus, Ly-2-L3T4- cells from embryonic CBA thymus lacked F23.1-positive cells. Subsets of adult CBA Ly-2-L3T4- thymocytes were separated to determine which expressed V beta 8. The major subset, Ly-1 low B2A2-M1/69+Thy-1+Pgp-1-, representing a phenotype similar to embryonic Ly-2-L3T4- thymocytes and the phenotype commonly isolated from adult thymocytes as Ly-1 "dull," lacked cells strongly positive for F23.1. In contrast, a series of subsets of adult CBA Ly-2-L3T4- thymocytes which were B2A2-M1/69- and Pgp-1+ all included strongly F23.1-positive cells. A minor subset, negative for most markers except Pgp-1 and presumed on the basis of this phenotype and some reconstitution studies to include the earliest intrathymic precursors, contained 28% F23.1-positive cells. However, no F.23.1-positive cells were detected in equivalent "prethymic" populations from bone marrow or from athymic mouse spleen. The subsets of Ly-2-L3T4- thymocytes which were Ly-1 high, B2A2-M1/69-, and Pgp-1+ all contained about 70% F23.1-positive cells, indicating a V beta 8 usage much higher than the mature T cell average. These results indicate that a series of distinct developmental events have occurred within these CD4-CD8- thymocytes previously considered as a single group of early precursor cells, and that some aspects of repertoire selection may be occurring amongst thymocytes which lack CD4 or CD8.     

In vitro induction of CD8 expression on thymic pre-T cells. I. Transforming growth factor-beta and tumor necrosis factor-alpha induce CD8 expression on CD8- thymic subsets including the CD25+CD3-CD4-CD8- pre-T cell subset.

We previously reported that IL-7 maintains the viability and differentiation potential of CD25 (IL-2R p55) positive CD3-CD4-CD8- thymic pre-T cells in vitro. This culture system is suitable for studying signals that regulate differentiation of T cell precursors in the thymus. In this study, we screened cytokines for their capacity to induce CD4 or CD8 in murine thymic pre-T cells cultured with IL-7. Of 15 cytokines tested, only transforming growth factor (TGF-beta) and TNF-alpha induced CD8 (Lyt-2), while no cytokine was able to induce CD4 on CD25+CD3-CD4-CD8- thymocytes. The combination of TGF-beta and TNF-alpha was synergistic, and the majority of cells recovered after 2 to 3 days in culture expressed CD8 (but not CD3 or CD4). A similar effect of TGF-beta and TNF-alpha was observed using day-15 fetal thymocytes, CD3+CD4-CD8- or CD3+CD4+CD8- adult thymocytes, although the combination of these cytokines resulted in an additive rather than a synergistic effect in these subsets. In contrast, neither TGF-beta nor TNF-alpha induced CD8 expression on splenic CD4+CD8- T cells. These observations suggest a role for these cytokines in the induction of CD8 expression in CD8- thymocyte subsets including CD3-CD4-CD8- thymic pre-T cells.     

Clonal analysis of human CD4-CD8-CD3- thymocytes highly purified from postnatal thymus.

Human triple-negative (CD4-CD8-CD3-) thymocytes purified from postnatal thymus by the use of magnetic bead columns and cell sorting were cultured in bulk or cloned with a feeder cell mixture of irradiated PBL, irradiated JY cells, and PHA. Triple-negative thymocytes proliferated well under these culture conditions, and after 12 days in bulk culture they remained triple negative. Limiting dilution experiments revealed that the frequency of clonogenic cells in fresh triple-negative thymocytes was less than 1%. Of 40 clones obtained in a representative experiment, 37 were triple negative and 3 were CD4+ TCR-alpha beta+. No TCR-gamma delta+ clones were isolated. Some of the triple-negative clones expressed CD16 and were apparently NK cells. Seven representative CD16-triple-negative clones were expanded and characterized in detail. These clones shared the common cell surface phenotype of CD1-CD2+CD3-CD4--CD8-CD5-CD7+CD16-CD56+. One of them expressed cytoplasmic CD3 delta and CD3 epsilon Ag, but these Ag were not detected in any peripheral blood-derived CD16- NK clones examined for comparison. The seven CD16- thymus-derived clones exhibited significant cytolytic activity against K562. The clone that expressed cytoplasmic CD3 Ag was shown to have the germ-line configuration of the TCR-beta and TCR-gamma genes. Thus, it is suggested that in vitro culture of triple-negative thymocytes can give rise to NK-like cells, including those that express cytoplasmic CD3 Ag. In contrast to previous reports, our results gave no evidence of differentiation of triple-negative thymocytes into TCR-alpha beta+ or TCR-gamma delta+ T cells.