CD4单克隆抗体改变新生小鼠胸腺亚群的分布和功能

新生期小鼠腹腔注入ＣＤ４，ＭｃＡｂ、可引起胸腺细胞表型和功能变化。胸腺细胞表型分析显示；胸腺细胞总数，ＤＰ和ＣＤ４ＳＰ细胞明显减少；ＣＤ８ＳＰ细胞数增加ＤＮ细胞数目变化不大。上述变化与ＣＤ４ＭｃＡｂ和胸腺细胞表面的ＣＤ４分子的结合有关。功能试验表明：实验组小鼠胸腺细胞对有丝分裂素ＣｏｎＡ，ＰＷＭ的反应性降低，混合淋巴细胞反应也明显低于对照组。     

CD4单克隆抗体在体内诱导小鼠胸腺细胞凋亡

为研究抗ＣＤ４ ＭｃＡｂ引起胸腺细胞减少的机理，本课题探讨了ＣＤ４ ＭｃＡｂ诱导胸腺细胞发生凋亡的可能性。小鼠注射抗ＣＤ４ ＭｃＡｂ后，皮质胸腺细胞体积缩小，染色质凝聚；ＰＩ染色后经流式细胞计测定，显示大量的亚二倍体细胞（凋亡细胞，Ａｐｏｐｔｏｔｉｃ ｃｅｌｌｓ），与正常小鼠相比Ｐ〈０．００１；片断化ＤＮＡ的百分比也明显高于正常小鼠，Ｐ〈０．０１。片断化ＤＮＡ在凝胶电泳上呈现典型的阶梯现象。细胞内     

抗D型葡萄球菌肠毒素单克隆抗体的研制及其初步应用

应用小鼠杂交瘤技术获得了５株分泌抗Ｄ型葡萄球菌肠毒素（ＳＥＤ）ＭｃＡｂ的杂交瘤细胞（ＤＣ３、ＤＣ４、ＤＢ１１、４Ｄ３和４Ｄ５）。其中４Ｄ３为ＩｇＭ（λ），其余为ＩｇＧ１（ｋ）。这组ＭｃＡｂ除ＤＣ３外，其它４株ＭｃＡｂ识别的抗原构象表位相同，其相亲和力依次为４Ｄ５〉ＤＣ３〉ＤＣ４〉４Ｄ３〉ＤＢ１１。利用抗ＳＥＤ多克隆抗体ＨＲＰ标记的ＤＣ３和４Ｄ３（针对不同表位）混合ＭｃＡｂ建立了夹心ＥＬＩＳＡ法，并     

PMA和PHA对活化早期人胎儿胸腺细胞表型分化的研究

本文利用妊娠中期水囊引产的人胎儿胸腺细胞，采用双色免疫荧光染色技术用流式细胞计分析了佛波酯（ＰＭＡ，一种ＰＫＣ激酶活化剂）和ＰＨＡ作用于胸腺细胞０．５，３，６，１２和１８小时等不同时间对胸腺细胞ＣＤ４＋ＣＤ８＋亚群（ＤＰ）表型变化的影响。结果表明ＰＭＡ作用３０分钟就可以明显下调ＤＰ亚群ＣＤ４分子表达，而其对ＣＤ８分子的下调作用明显晚于对ＣＤ４分子的作用。ＰＨＡ则不表现对ＣＤ４分子的下调作用。我们发现ＰＭＡ和ＰＨＡ还可下调ＣＤ３的表达，但是ＰＭＡ和ＰＨＡ对ＩＬ－２受体和ＨＬＡ－Ⅰ类抗原的表达有促进作用。而对ＤＲ分子均无明显作用。这些结果证实胸腺ＤＰ细胞在外界活化因子作用下一些重要的细胞表面分子发生了改变，表明胸腺ＤＰ细胞具有继续分化的潜能。提示在ＰＭＡ和ＰＨＡ诱导的胸腺细胞活化和增植过程中细胞表面分子的表达可能受不同细胞活化机制的调控。因此，探讨ＰＭＡ和ＰＨＡ诱导细胞表型变化的机理及其与胸腺细胞活化的关系可能有助于对Ｔ细胞活化机理研究。     

MTEC 1分泌的趋化因子引起特定亚群胸腺细胞的定向迁移

分析胸腺髓质上皮样细胞系ＭＴＥＣ１分泌的化学趋化因子对胸腺细胞亚群的趋化作用。方法以抗体加补体杀伤结合免疫磁珠及ｐａｎｎｉｎｇ法，将小鼠胸腺细胞分离纯化，获得ＣＤ４＋ＣＤ８＋（ＤＰ），ＣＤ４－ＣＤ８－（ＤＮ），ＣＤ４＋ＣＤ８－（ＣＤ４ＳＰ）及ＣＤ４－ＣＤ８＋（ＣＤ８ＳＰ）四亚群细胞，用Ｂｏｙｄｅｎ小室分析ＭＴＥＣ１┐ＳＮ对四群胸腺细胞的趋化作用。结果ＭＴＥＣ１┐ＳＮ对ＤＰ及ＣＤ４ＳＰ胸腺细胞有趋化活性（ＣＩ＝６．６±１．０及６．１±１．８）；对ＣＤ８ＳＰ细胞有中度趋化活性（ＣＩ＝３．２±１．０）；对ＤＮ趋化活性微弱（ＣＩ＝１．３±０．６）。化学趋化因子ＭＣＰ┐１纯品对ＣＤ４ＳＰ胸腺细胞显示强趋化活性（ＣＩ＝５．６），对ＤＮ胸腺细胞则无可测出趋化活性。结论ＭＴＥＣ１分泌的化学趋化因子对ＤＰ，ＣＤ４ＳＰ及ＣＤ８ＳＰ胸腺细胞有显著趋化作用，对ＤＮ胸腺细胞几乎无趋化作用。提示此类化学趋化因子有趋使胸腺发育中后期阶段的细胞向胸腺髓质区迁移和定位的作用。     

SLE患者AMLR与T细胞Ia抗原的改变及意义

本文以氚标胸腺嘧啶（＾３Ｈ－ＴｄＲ）掺入的淋巴细胞转化试验测定非Ｔ细胞刺激自身Ｔ细胞的增殖反应（ＡＭＬＲ）；用单克隆抗体（ＭｃＡｂ）Ｗｕ３５和Ｗｕ２２通过ＰＡＰ免疫酶标组化技术测定ＣＤ３＾＋，ＣＤ４＾＋，Ｃｄ８＾＋Ｔ细胞表面ＤＲ及ＤＱ抗原的表达。结果表明，活动期ＳＬＥ患者ＡＭＬＲ有明显减弱，Ｗｕ＾３５＋（ＨＬＡ－ＤＲ＾＋）Ｔ细胞增加为主，ＣＤ８＾＋ＤＲ＾＋及ＣＤ８＾＋ＤＱ＾＋细胞则表现为减少。提示     

两种小鼠胸腺基质细胞对胸腺细胞凋亡的不同作用

采用两种体外建系的小鼠胸腺基质细胞（ＴＳＣ）系，即上皮样ＴＳＣ（ＭＴＥＣ１）和树突状ＴＳＣ（ＭＴＳＣ４），观察其对胸腺细胞凋亡的影响。小鼠胸腺细胞在体外培养过程中，可自发地出现细胞凋亡的特征，表现为ＤＮＡ呈梯度断裂片段，细胞经ＦＡＣＳ分析出现亚二倍体ＤＮＡ波峰，以及Ｆｅｕｌｇｅｎ′ｓ染色镜检所见的ＤＮＡ凝聚和断裂。胸腺细胞在与ＴＳＣ共育后，在ＭＴＥＣ１组可见其凋亡过程受到抑制和存活率的增加；在ＭＴＳＣ４组，仅在共育１２至１８小时时，见到胸腺细胞凋亡加强，而其存活率不受影响。结果提示在胸腺细胞发育过程中，其阴性选择作用的主要机制之一的ＰＣＤ过程受不同来源的胸腺基质细胞的调节。     

黄芪多糖、人参茎叶皂甙对创伤小鼠血浆及免疫细胞内cAMP、cGMP的影响

本实验利用小鼠闭合性创伤模型，观察创伤后第４天小鼠血浆、免疫细胞内ｃＡＭＰ、ｃＧＭＰ含量的变化及黄芪多糖（ＡＰＳ）、人参茎叶皂甙（ＧＳ）的调节作用。结果显示：创伤后小鼠血浆内ｃＡＭＰ水平增高，ｃＧＭＰ水平下降，ＣＡＭＰ／ｃＧＭＰ比值升高。腹腔巨噬细胞及脾细胞、胸腺细胞、肠系膜淋巴结细胞在静息状态和激活状态时的ｃＡＭＰ、ｃＧＭＰ含量也显示相似的改变。ＡＰＳ（２５０ｍｇ／ｋｇ）、ＧＳ（５０ｍｇ／ｋｇ）体内应用（每天一次，连续４天）可明显降低创伤小鼠血浆及免疫细胞内ｃＡＭＰ水平，升高其ｃＧＭＰ水平。一定浓度范围内的ＡＰＳ（５０～２５０μｇ／ｍｌ）、ＧＳ（１．０～１００μｇ／ｍｌ）在体外可明显拮抗创伤小鼠激活状态的巨噬细胞及脾细胞内ｃＡＭＰ／ｃＧＭＰ比值的增高。提示：ＡＰＳ，ＧＳ可纠正创伤小鼠血浆及免疫细胞内ｃＡＭＰ、ｃＧＭＰ的比例失衡。     

小鼠胸腺基质细胞株中细胞多核化现象探讨

在建立小鼠胸腺基质细胞株时发现小鼠胸腺基质细胞株ＭＴＳＣＢ和ＭＴＳＣＣ自发产生多核细胞及单核巨细胞，对上述细胞进行了非特异性酯酶（ＮＳＥ）、酸性磷酸酶（ＡｃＰ）和琥珀酸脱氢酶（ＳＤＨ）反应，多核细胞及单核巨细胞的ＮＳＥ、ＡｃＰ和ＳＤＨ活性均强于单核小细胞。在ＭＴＳＣＢ中多核细胞的百分数为１．１％；ＭＴＳＣＣ中多核细胞为０．６％，实验中对一核细胞和多核细胞出现的百分数与Ｐｏｉｓｓｏｎ分布的理论频率进     

抗D型葡萄球菌肠毒素单克隆抗体的研制及其初步应用

应用小鼠杂交瘤技术获得５株分泌抗Ｄ型葡萄球菌肠毒素（ＳＥＤ）ＭｃＡｂ的杂交瘤细胞（ＤＣ３、ＤＣ４、ＤＢ１１、４Ｄ３和４Ｄ５）。其中４Ｄ３为ＩｇＭ（λ），其余为ＩｇＧ１（ｋ）。这组ＭｃＡｂ除ＤＣ３外，其它４株ＭｃＡｂ识别的抗原构象表位相同，其相对亲和力依次为４Ｄ５＞ＤＣ３＞ＤＣ４＞４Ｄ３＞ＤＢｌｌ。利用抗ＳＥＤ多克隆抗体与ＨＲＰ标记的ＤＣ３和４Ｄ３（针对不同表位）混合ＭｃＡｂ建立了夹心ＥＬＩＳＡ法，并以该法检测了自临床标本中分离的８０林金葡萄菌所产生的ＳＥＤ，其产毒率为４１．３％。     

Sequential analysis of the thymocyte differentiation in fully allogeneic bone marrow chimera in mice. I. Relationship between functions and surface characteristics of thymocytes

Differentiation of thymocytes according to surface phenotype, functional status and cell size was investigated using fully allogeneic bone marrow chimeras. Most of the donor-derived thymocytes obtained from chimeras 9 days after hematopoietic reconstitution were CD4-8- and IL2R+. At day 14, CD4+8+ cells became prominent in the thymus. Eighty-six per cent of thymocytes were CD4+8+ and 9% were CD4-8- at this stage. After day 21, the proportion of CD4+8- or CD4-8+ single positive cells transiently increased and then declined to normal level at day 42. Further, the mean size of CD4+ or CD8+ single positive cells in chimeric thymuses at day 21 after reconstitution was markedly larger than that at day 35. When proliferative responses to various stimuli (PMA + rIL2, anti-CD3 mAb (2C11) and anti-V beta 8 mAb (F23.1] were evaluated, significant responses were generated by thymocytes for the first time at around day 28 and the responses reached their peaks at day 35. These findings demonstrated that the process of thymocyte differentiation in the fully allogeneic chimeras was similar to ontogenic development as observed in fetal mice. However, the tempo at which the differentiation of surface phenotypes and development of functions proceeded was quite different from that seen in normal mice. The relationship among surface phenotypes, cell size and functions of developing thymocytes of bone marrow chimeras is discussed.     

Functional and phenotypic delineation of two subsets of CD4 single positive cells in the thymus

CD4 single positive thymocytes are the fraction of mature thymocytes that contains precursors of MHC class II restricted T cells. In the experiments presented here, we demonstrate phenotypic and functional heterogeneity amongst CD4 single positive thymocytes from adult mice. Approximately 70% of these cells adhere to anti-CD8 antibody-coated dishes and therefore express low levels of CD8 molecules. They are referred to here as CD8loCD4hi. The remaining 30% are CD8-CD4hi. The CD8loCD4hi subset also expresses 3-fold higher surface levels of heat-stable antigen (HSA) than CD8-CD4hi thymocytes. Both CD4hi subsets express high levels of the alpha beta TCR/CD3 complex on the cell surface, and can proliferate in response to allogeneic cells expressing MHC class II differences but not to cells expressing only class I disparate molecules. However, CD8-CD4hi thymocytes are self-sufficient in such a proliferative response, whereas CD8loCD4hi thymocytes require exogenous IL-2 for optimal proliferation. The results suggest that CD8loCD4hi thymocytes are not completely mature. Their phenotype suggests that they might be descendants from CD8hiCD4hi double positive thymocytes, and that they have begun to down-regulate gradually CD8 and HSA molecules. The relationship between the two CD4hi single positive subsets is discussed.     

Induction of tolerance by mixed chimerism with nonmyeloblative host conditioning: the importance of overcoming intrathymic alloresistance.

A nonmyeloablative conditioning regimen, consisting of depleting doses of anti-CD4 and anti-CD8 monoclonal antibodies (MoAbs) given on days -6 and -1 and 3 Gy of whole body irradiation given on day 0, allows the engraftment of fully major histocompatibility complex (MHC)-mismatched allogeneic bone marrow and the induction of tolerance for the graft. If MoAbs are given on day -5 only, permanent chimerism and tolerance are not observed in most animals. The addition of thymic irradiation to the single MoAb treatment permits tolerance induction in these mice, suggesting that residual host thymocytes reject donor marrow in recipients of 1, but not 2, MoAb injections. In this study, both CD4+ and CD8+ thymocytes were found to be responsible for residual alloreactivity in mice receiving only 1 MoAb injection. Co-receptor coating and downmodulation on residual thymocytes occur to a greater extent in recipients of 2 MoAb injections than in recipients of a single MoAb injection. This downmodulation may play a role in the loss of alloreactivity. Our results suggest that a second MoAb injection inactivates mature, functional donor-alloreactive CD4+ and CD8+ host thymocytes.     

T cell receptor excision circle assessment of thymopoiesis in aging mice

Signal joint T cell receptor delta (TCRD) excision circles (TRECs) are episomal DNA circles generated by the DNA recombination process that is used by T lymphocytes to produce antigen-specific alpha/beta T cell receptors. Measurement of TRECs in thymocytes and peripheral blood T cells has been used to study thymus output in chickens and humans. We have developed a real-time quantitative-PCR assay for the specific detection and quantification of mouse TCRD episomal DNA circles excised from the TCRA locus during TCRA gene rearrangement (mTRECs). We found that the mouse TCRD TRECs detected with this assay were predominantly in na?ve phenotype CD4(+) and CD8(+) T cells. In a series of aged mice (range 6-90-week-old) we determined the absolute number of thymocytes and the number of molecules of mTRECs/100,000 thymocytes. We found that the absolute number of thymocytes dramatically decreased with age (P<0.05) and that molecules of mTREC/100,000 thymocytes also declined with mouse age (P<0.05). Splenocytes were isolated from aging mice and the frequency of na?ve phenotype CD4 and CD8 cells determined. There was a significant drop in both CD4 and CD8 na?ve peripheral T cells in the aged mice over time. mTREC analysis in purified CD4(+) and CD8(+) splenocytes demonstrated a constant level of mTRECs in the CD4 compartment until age 90 weeks, while the mTRECs in the CD8 compartment fell with age (P<0.05). By combining the mouse TREC assay with T cell phenotypic analysis, we demonstrated that IL-7 administration to young mice induced both increased thymopoiesis and peripheral T cell proliferation. In contrast, IL-7 treatment of aged mice did not augment thymopoiesis, nor induce expansion of splenic T cells. Thus, thymus output continues throughout murine adult life, and the thymic atrophy of aging in mice is not reversed by administration of IL-7.     

Lymphocyte changes associated with prolongation of cardiac allograft survival in adult mice using anti-CD4 monoclonal antibody.

This study investigated the effect of anti-CD4 MoAb treatment on lymphocyte phenotype and function and correlated these changes with the prolongation of cardiac allograft survival in adult mice. Indefinite survival of heterotopic cardiac allografts was obtained in several fully allogeneic strain combinations when two doses of the anti-CD4 MoAb, YTS 191.1, were given at the time of transplantation. A dose response analysis in the C57BL/10 to C3H/He strain combination showed that very low doses of YTS 191.1 (25 micrograms/dose) were able to induce prolonged allograft survival when administered perioperatively. At the time of transplantation the immunosuppression induced by administration of the anti-CD4 MoAb is not antigen-specific, as heart grafts from different donor strains, mismatched for both major and minor histocompatibility antigens, showed prolonged survival in treated recipients. Immunocompetence was restored by 6 weeks after MoAb treatment, as recipients regained the ability to reject a cardiac allograft transplanted at this time point. However, while recovery of immunocompetence could be demonstrated in vivo, leucocytes isolated from the peripheral lymphoid organs of treated mice continued to be hyporesponsive in mixed leucocyte culture (MLC). Phenotypic analysis of the peripheral lymphoid tissues showed that C3H/He recipients treated with 25 micrograms/dose of YTS 191.1 had a marked, but not complete, elimination of the CD4+ subset at the time of transplantation, which was gradually restored to 50% of normal by 6 weeks after treatment. Thus, complete elimination of the CD4+ subset was not required to achieve indefinite allograft survival, and immunocompetence, as assessed in vivo, returned even when the CD4+ subset was present at half the normal level. Low doses of anti-CD4 MoAb (25 micrograms) had no effect on the expression of the CD4 molecule by thymocytes, and yet thymocytes were hyporesponsive to alloantigen in vitro. At higher doses of YTS 191.1, immature CD4+8+ thymocytes were selectively depleted. These results suggest that anti-CD4 MoAb therapy may modulate the intrathymic T cell selection process. These studies provide further insight into the mechanism of action of low dose, depleting anti-CD4 MoAb therapy in allograft rejection, and form a basis from which rational modifications to therapeutic protocols in transplantation models can be made.     

Induction of IL-15 by TCR/CD3 aggregation depends on IFN-gamma and protects against apoptosis of immature thymocytes in vivo

TCR/CD3 aggregation by injection of anti-CD3 Ab produces T cell activation, release of cytokines such as IFN-gamma, and apoptosis in the cortical region of the thymus. We show that anti-CD3 Ab induces IL-15 mRNA in spleens of wild-type but not IFN-gamma receptor-knock-out (IFN-gammaR KO) mice. The loss of IL-15 mRNA induction in IFN-gammaR KO mice was associated with increased thymocyte apoptosis. Pretreatment of wild-type mice with neutralizing anti-IL-15 Ab increased the anti-CD3-triggered thymocyte apoptosis, thus mimicking the sensitive phenotype of IFN-gammaR KO mice. Inversely, anti-CD3-induced apoptosis in IFN-gammaR KO mice was suppressed by administration of recombinant IL-15. In IFN-gammaR KO mice and in wild-type mice that were treated with anti-IL-15, augmented apoptosis affected mainly CD4+CD8+ immature thymocytes. IL-15 as well as IL-15Ralpha mRNA expression in thymocytes was not increased by anti-CD3. These data demonstrate that systemic IL-15 exerts anti-apoptotic activity on immature T cells and establish a regulatory mechanism whereby TCR/CD3 engagement induces IL-15 expression via an IFN-gamma-dependent pathway. The self-amplifying nature of this IFN-gamma/IL-15 connection may constitute a regulatory pathway in central tolerance to self.     

Intrathymic changes in murine CD3, CD5 and CD8 expression after in vivo administration of anti-CD4.

Intrathymic development of murine cortical and medullary thymocyte subpopulations was examined after in vivo administration of anti-CD4 mAb. Four days after mice received 1 mg anti-CD4, expression of CD4 was reduced to about 25% the levels of controls. On cortical CD8+/PNAhigh thymocytes, CD5 and CD8 expression both decreased, but not in parallel, whereas CD3 expression increased almost 2-fold. Partial shifts in CD3 expression were seen 3 and 6 h after injection, but modulation of CD4 preceded the increase in CD3 expression. On medullary CD8-/PNAlow thymocytes, both CD3 and CD5 were down regulated. On nontargeted CD8+/PNAlow medullary thymocytes, expression of these molecules was decreased less than 20%, but the decrease in CD8 expression was primarily due to the appearance of a CD8low subpopulation. The results indicate that anti-CD4 mAb differentially affects the intrathymic development of T cell populations.     

CD4+ helper T cells are required for resistance to a highly metastatic murine tumor

A role of CD4+ T helper cells in induction of tumor transplant rejection leading to complete regression of a highly metastatic DBA/2 mouse lymphoma was analyzed. Using an anti-CD4 monoclonal antibody (GK1.5) which eliminates T helper cells in vivo and in vitro, we found that CD4+ cells are required for tumor resistance in syngeneic DBA/2 mice or allogeneic but major histocompatibility complex-identical B10.D2 mice. In contrast, in allogeneic C57BL/6 mice tumor rejection was independent of CD4+ cells. An analogous requirement for immune CD4+ cells for in vitro induction of CD8+ tumor-specific cytotoxic T cells was found in these respective strains. The requirement for immune CD4+ cells in vitro could be replaced by recombinant interleukin 2. These results demonstrate a role of CD4+ regulatory T cells and T-T cell cooperation in the induction of anti-tumor immunity and tumor rejection, and point to possible therapeutic interventions in the afferent phase of anti-tumor immune responses.     

The origin of thymic CD4+CD25+ regulatory T cells and their co-stimulatory requirements are determined after elimination of recirculating peripheral CD4+ cells

Studies on the thymic ontogeny of naturally arising CD4(+)CD25(+) regulatory T cells (TR cells) are complicated by the contamination of recirculating cells from the periphery (both activated CD4(+) T and TR cells). We investigated TR cells in anti-CD4 antibody transgenic (Tg) (GK) mice that continuously deplete peripheral CD4 T cells but not thymocytes so that the generation of thymic TR cells and their developmental requirement can be accurately assessed. We show that in the thymuses of mice that lack peripheral CD4(+) cells, TR cells were present but were fewer in number compared with wild-type (WT) mice. Therefore, we show that peripheral TR cells do re-enter the thymus, comprising 20% of TR cells in the normal thymus. TR cells from both WT and GK mice expressed Foxp3 and GITR, and suppressed the proliferation of CD25(-)CD4(+) T cells. Furthermore, the co-stimulation requirements for TR generation were evaluated in mice with or without peripheral CD4 cells. Splenic TR cells in CD40L(-/-) mice and CTLA4Ig Tg mice were fewer compared with WT mice. Mice deficient in both co-stimulatory pathways had further reduction in splenic TR cells. Unlike the periphery, the reduction in thymic TR cells was only seen for CD40L(-/-) but not for CTLA4Ig Tg mice. Therefore, we found that the co-stimulation requirements for the thymic development of TR cells differed from those for peripheral homeostasis.