抗CD3,CD28单抗对人T淋巴细胞共刺作用的影响因素

以抗ＣＤ３和抗ＣＤ２８作为Ｔ细胞激活的第一和第二信号，观察二者不同浓度，不同作用顺序和不同作用时间对人Ｔ淋巴细胞增殖反应的影响。结果显示单一的抗ＣＤ３和抗ＣＤ２８不能刺激Ｔ细胞增殖，只有同时域在一定时间内接受二者的共同刺激才能促使细胞增殖。     

CD4~+ CD28~- T淋巴细胞与自身免疫性疾病

CD4+CD28-T细胞是一个具有特殊生物学效应的细胞亚群,高频出现于某些自身免疫性疾病中,具有细胞毒样的侵蚀特性、T细胞活化的不平衡性及抗凋亡特征,与疾病的发生、发展及转归密切相关。     

抗 CD3 、 CD28 单抗对人 T 淋巴细胞共刺激作用的影响因素

以抗 Ｃ Ｄ３ 和抗 Ｃ Ｄ２８ 作为 Ｔ 细胞激活的第一和第二信号, 观察二者不同浓度, 不同作用顺序和不同作用时间对人 Ｔ淋巴细胞增殖反应的影响。结果显示单一的抗 Ｃ Ｄ３ 和抗 Ｃ Ｄ２８ 不能刺激 Ｔ 细胞增殖, 只有同时或在一定时间内接受二者的共同刺激才能促使 Ｔ 细胞增殖。单独接受抗 Ｃ Ｄ３ ２４ｈ 或抗 Ｃ Ｄ２８ １６ｈ 后, Ｔ 细胞对相应的另一信号刺激呈低反应性, 这一现象可能与 Ｔ细胞耐受及自身免疫病的发生有关。     

CD28／CTLA4：B7在T细胞激活和效应过程中的共刺激作用

抗原特异性Ｔ细胞的激活需要ＴＣＲ－ＣＤ３复合体接受抗原提呈细胞提呈的抗原信息，同时还需多种辅助分子提供的共刺激信号。ＣＤ２８／ＣＴＡＬ４：Ｂ７介导的共刺激信号在ＣＤ４Ｔ细胞激活、ＣＤ８Ｔ细胞杀伤活性的诱导和效应过程中起重要作用。本文综述了ＣＤ２８／ＣＴＬＡ：Ｂ７的分子特性，在Ｔ细胞激活、效应过程中的共刺激作用，ＣＤ２８介导的信号传导途径及在肿瘤免疫、移植免疫研究中的意义。     

CD28单抗对CD3AK细胞增殖及表型的影响

CD3AK细胞是用小剂量CD3单抗交联CD3分子而活化的T细胞 ,它具有较强的细胞增殖和细胞毒效能。CD2 8分子则是T细胞激活过程中所需的协同刺激分子 ,可提供T细胞活化所需的第二信号。本文利用CD2 8单抗作为CD2 8分子的配体 ,观察了CD2 8信号途径的激活对CD3AK细胞的影响。结果显示CD2 8单抗可增强CD3AK细胞的增殖活性和趋化团聚形成集落的能力 ,并优先引起CD4+T细胞的增殖。     

LIGHT 一个新的非CD28依赖的T细胞共刺激分子

ＬＩＧＨＴ(ｆｏｒｈｏｍｏｌｏｇｏｕｓｔｏｌｙｍｐｈｏｔｏｘｉｎｓ ,ｅｘｈｉｂｉｔｓｉｎ ｄｕｃｉｂｌｅｅｘｐｒｅｓｓｉｏｎ ,ａｎｄｃｏｍｐｅｔｅｓｗｉｔｈＨＳＶｇｌｙｃｏｐｒｏｔｅｉｎＤｆｏｒＨＶＥＭ ,ａｒｅｃｅｐｔｏｒｅｘｐｒｅｓｓｅｄｂｙＴｌｙｍｐｈｏｃｙｔｅｓ) 〔1〕是1998年发现的ＴＮＦ超家族成员 ,又称为ＨＶＥＭ Ｌ(ｈｅｒｐｅｓｖｉｒｕｓｅｎｔｒｙｍｅｄｉａｔｏｒ ｌｉｇａｎｄ) 〔2〕 是肿瘤坏死因子超家族的第 14个成员 (ＴＮＦＳＦ14)。由于ＬＩＧＨＴ同时具有诱导肿瘤细胞凋亡和共刺激Ｔ细胞活化的…     

抗CD3单抗对T细胞的作用

抗ＣＤ３单抗可作为一种免疫调节剂对Ｔ细胞的多种功能产生调节作用，它与ＩＬ－２具协同作用，诱导Ｔ细胞扩增，增强胞毒活性，体内转输ＣＤ３－ＡＫ细胞能降低肿瘤的转移和生长，高剂量的抗ＣＤ３单抗具有免疫抑制作用。该抗体对Ｔ细胞的作用机制目前尚不十分清晰，可能与磷酸肌醇，细胞内Ｋ＾＋、Ｃａ＾＋浓度的变化以及ＩＬ－１，ＩＬ－６和ＩＬ－２的级联相关作用有关。     

CD28/B7信号在再生障碍性贫血T淋巴细胞异常活化中的作用

目的 通过淋巴细胞输注诱导自身免疫性再生障碍性贫血动物模型,探讨CD28/B7信号在淋巴细胞异常活化中的作用及可能机制.方法 将来自父本的淋巴细胞悬液(40×106个几左右)通过尾静脉注入CBYB6 F1代受鼠体内,采用CFDA-SE标记法跟踪淋巴细胞在体内的分布,尾静脉注射CD80和CD86阻断性单克隆抗体(单抗),不同时段检测受体小鼠外周血象的变化,病理切片观察骨髓及主要脏器的变化.将骨髓造血细胞与淋巴结淋巴细胞进行共培养,通过计数造血细胞的集落形成数来观察不同数量淋巴结淋巴细胞对骨髓造血细胞的影响.体外测试不同浓度环孢菌素A(cyclosporine A,CsA)对骨髓造血细胞的影响.结果 输注淋巴细胞后可诱导受体小鼠在第5天出现骨髓衰竭的表现,主要是白细胞、血红蛋白、血小板下降,21 d左右受体鼠出现死亡.不同时间段受体小鼠主要脏器冰冻切片显示荧光标记的淋巴细胞主要分布在骨髓组织中;病理切片显示有骨髓组织的破坏.同时注射CD80及CD86阻断性单抗的受体鼠同样出现上述表现;体外集落形成试验证实B6淋巴结淋巴细胞数量和F1造血细胞为5:1时,红系集落形成单位(CFU-E)和粒细胞集落形成单位(CFU-G)集落形成数目与空白组比较差异无统计学意义(P>0.05);将比例提高至10:1,CFU-E集落形成数目明显减少(P<0.05);至50:1时,则可完全抑制CFU-E集落的形成,CFU-E和CFU-G集落形成数日的减少呈现淋巴细胞剂量依赖性,加入CsA可显著提高CFU-E和CFU-G形成率.结论 通过模型证实T细胞在再生障碍性贫血的发生过程中起重要作用,仅通过阻断CD28/B7信号并不能阻断T淋巴细胞的异常活化.     

抗CD28─超抗原活化T细胞的TCRVβ特异性

对ＡＰＣ辅助超抗原活化Ｔ细胞的确切机制迄今仍不十分清楚。近年来有实验报道，在体外缺乏ＡＰＣ的情况下，仅靠ＣＤ２８分子的共刺激超抗原仍可活化Ｔ细胞。本实验对该情况下超抗原ＴＳＳＴ－１活化Ｔ细胞的ＴＣＲＶβ特异性进行鉴定，旨在观察单靠ＣＤ２８分子的共刺激ＴＳＳＴ－１活化Ｔ细胞是否仍保留超抗原所特有的方式。结果显示，ＴＳＳＴ－１在ＣＤ２８分子的共刺激下活化人的Ｔ细胞确是与其在ＡＰＣ辅助下活化人Ｔ细胞的方式一致，即均以ＴＣＲＶβ２特异性的方式。提示ＡＰＣ可能主要通过提供ＣＤ２８分子的共刺激来辅助超抗原活化Ｔ细胞     

A fundamental difference in the capacity to induce proliferation of naive T cells between CD28 and other co-stimulatory molecules

T cell activation requires two signals: a signal from the TCR and a co-stimulatory signal provided by antigen-presenting cells (APC). In addition to CD28, multiple molecules on the T cell have been described to deliver co-stimulatory signals. Here, we investigated whether there exist quantitative or qualitative differences in the co-stimulatory capacity between CD28 and other molecules. Anti-CD28 monoclonal antibody (mAb) and mAb against CD5, CD9, CD2, CD44 or CD11a all induced activation of naive T cells in the absence of APC when co-immobilized with a submitogenic dose of anti-CD3 mAb. [ ³ H]Thymidine incorporation determined 2 days after co-stimulation was all comparable. In contrast to progressive T cell proliferation induced by CD28 co-stimulation, co-stimulation by other T cell molecules led to a decrease in viable cell recovery along with the induction of apoptosis of once activated T cells. This was associated with a striking difference in IL-2 production; CD28 co-stimulation induced progressively increasing IL-2 production, whereas co-stimulation by other molecules produced limited amounts of IL-2. Addition of recombinant IL-2 to the latter cultures corrected the induction of apoptosis, resulting in levels of cellular proliferation comparable to those observed for CD28 co-stimulation. These results indicate that a fundamental difference exists in the nature of co-stimulation between CD28 and other molecules, which can be evaluated by the levels of IL-2 production, but not simply by [ ³ H]thymidine incorporation.     

CD28 activation promotes Th2 subset differentiation by human CD4+ cells

Ligation of CD28 provides a costimulatory signal to T cells necessary for their activation resulting in increased interleukin (IL)-2 production in vitro, but its role in IL-4 and other cytokine production and functional differentiation of T helper (Th) cells remains uncertain. We studied the pattern of cytokine production by highly purified human adult and neonatal CD4⁺ T cells activated with anti-CD3, phorbol 12-myristate 13-acetate (PMA) and ionomycin, or phytohemagglutinin (PHA) in the presence or absence of anti-CD28 in repetitive stimulation-rest cycles. Initial stimulation of CD4⁺ cells with anti-CD3 (or the mitogens PHA or PMA+ionomycin) and anti-CD28 monoclonal antibodies induced IL-4, IL-5 and interferon-γ (IFN-γ) production and augmented IL-2 production (6- to 11-fold) compared to cells stimulated with anti-CD3 or mitogen alone. The anti-CD28-induced cytokine production corresponded with augmented IL-4 and IL-5 mRNA levels suggesting increased gene expression and/or mRNA stabilization. Most striking, however, was the progressively enhanced IL-4 and IL-5 production and diminished IL-2 and IFN-γ production with repetitive consecutive cycles of CD28 stimulation. The enhanced Th2-like response correlated with an increased frequency of IL-4-secreting cells; up to 70% of the cells produced IL-4 on the third round of stimulation compared to only 5% after the first stimulation as determined by ELISPOT. CD28 activation also promoted a Th2 response in naive neonatal CD4⁺ cells, indicating that Th cells are induced to express a Th2 response rather than preferential expansion of already established Th2-type cells. This CD28-mediated response was IL-4 independent, since enhanced IL-5 production with repetitive stimulation cycles was not affected in the presence of neutralizing anti-IL-4 antibodies. These results indicate that CD28 activation may play an important role in the differentiation of the Th2 subset in humans.     

High-frequency activation of single CD4+ and CD8+ T cells to proliferate and secrete cytokines using anti-receptor antibodies and IL-2(1).

A high cloning efficiency single-cell culture system was developed to define the activation requirements of isolated CD4+ and CD8+ T cells to proliferate and secrete cytokines. T cells were triggered using solid-phase anti-CD3 and anti-CD4 or anti-CD8 antibodies plus rIL-2. Activation was measured by microscopic scoring of proliferation and by measurement of cytokine production using the cytokine-responsive cell lines FDC-P1, which responds to GM-CSF, IL-3, IFN-gamma and IL-4, and 32D clone 3 which responds to IL-3 only. Whilst anti-CD3 plus rIL-2 triggered only 4% of peripheral T cells to proliferate, anti-CD3 plus anti-CD8 mAb triggered about 40% of CD8+ T cells; 80% of the resultant clones secreted cytokine and 90% of these were IL-3+. Anti-CD3 plus anti-CD4 mAb triggered proliferation in about 20% of CD4+ T cells, of which 34% formed cytokine-producing clones with 47% of these secreting IL-3. In addition to responding at higher frequency, CD8+ T cells formed larger clones which produced higher levels of cytokines than CD4+ cells. Cell separation on the basis of Pgp-1 expression suggested that this culture system did not select for previously activated cells. Whereas Pgp-1+ T cells from keyhole limpet haemocyanin (KLH)-primed mice were enriched in KLH-specific cells, no significant differences were observed in the clonogenicity or cytokine-secreting capacity of Pgp-1+ and Pgp-1- T cells from normal mice.     

CD28-dependent killing by human YT cells requires phosphatidylinositol 3-kinase activation

CD28/B7 interactions have been demonstrated to provide a co-stimulatory signal for the generation of CD8⁺ cytotoxic T lymphocytes in the absence of CD4⁺ T helper cells. The CD28 signals required for induction of cytotoxicity have yet to be described. To investigate further the biochemical signaling pathways associated with CD28-dependent cytotoxicity, we have studied the human thymic leukemia cell line, YT. YT cells kill B7⁺ targets in a non-major histocompatibility complex (MHC)-restricted, CD28-dependent manner. CD28 ligation on the surface of YT cells caused a rapid increase in the tyrosine phosphorylation of four major cellular substrates with masses estimated to be 110, 95, 85, and 44 kDa. The 110 and 85 kDa substrates were identified as the catalytic and regulatory subunits, respectively, of phosphatidylinositol 3-kinase (PI3-K). Engagement of CD28 caused the rapid receptor association and activation of PI3-K but did not activate phospholipase C_γ. CD28-induced tyrosine phosphorylation and PI3-K activation was independent of p56^lck protein tyrosine kinase (PTK) activity (previously reported to be associated with CD28) and was insensitive to inhibition by the PTK inhibitor herbimycin A. Two structurally and mechanistically dissimilar inhibitors of PI3-K, wortmannin and 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002) also failed to block CD28-dependent tyrosine phosphorylation events or the association of PI3-K with the CD28 receptor. However, both drugs inhibited CD28-dependent cytotoxicity and CD28 receptor associated PI3-K activity with IC₅₀ values similar to the reported IC₅₀ values for PI3-K inhibition. Although herbimycin A did not significantly block the observed CD28-dependent tyrosine phosphorylation or PI3-K activation, herbimycin did block CD28-dependent cytotoxicity in a dose-dependent manner. These data support a role for PI3-K activation in the CD28-dependent initiation of cytotoxic effector function and suggest that a herbimycin sensitive step(s) is either CD28-independent, resides within a PI3-K-independent CD28 signaling pathway, or is downstream of CD28-dependent PI3-K activation.     

Co-stimulation of T cells via CD28 inhibits human IgE production; reversal by pertussis toxin.

In lymphocyte cultures, IgE production was achieved by stimulating T cells with anti-CD2 and IL-2. Here we show that anti-CD28, in the presence or absence of IL-2, reduces this IgE production approximately 10-fold. This inhibition of IgE production was almost completely reversed by Pertussis toxin (PT). PT had no effect on IgE production when the cells were stimulated in the absence of anti-CD28. No major effects of PT were found on IgM production. PT had no effect on purified B cells, stimulated with IL-4 and anti-CD40. In the presence of saturating amounts of rIL-4 similar results were obtained, albeit the absolute amounts of IgE produced were higher in all situations. Furthermore, PT-induced IgE production was still dependent on IL-4, as was evident from experiments in which anti-IL-4 was added to the culture. The IgE enhancing effect was dependent on the adenosine diphosphate (ADP)-ribosyltransferase activity of PT, because a mutant molecule lacking this activity was not able to restore anti-CD28-induced inhibition of IgE synthesis. Thus, we show that co-stimulation with anti-CD28 causes an inhibition of T cell-dependent IgE production by B cells, which inhibition can be specifically overcome by PT. An analysis of the molecular pathways underlying this phenomenon may contribute to our understanding of the regulation of IgE synthesis in (patho)physiological conditions.     

CD3／CD28协同刺激诱导抵抗和清除HIV-1感染的检验研究与细胞亚群分析

目的通过CD3／CD28抗体协同刺激活化原代CD4^＋ T细胞,以复制具有抵抗和清除HIV-1能力的“Levine现象”,建立相关机理研究的实验模式,分析效应细胞的亚群特征。方法从外周血单个核细胞中分选高纯度的CD4’T细胞,以PHA／IL-2为对照,经CD3／CD28抗体刺激培养后,以CD45RO、CD62L和CCR7进行单细胞流式分析,鉴定细胞亚群及CCR5、CXCR4表达水平,以实时荧光定量法测定培养上清中的病毒载量。结果CD3／CD28抗体刺激下CD4^＋ T细胞明显增殖活化,原态细胞减少,明显转为记忆细胞表型,特别是M2亚群和TCM亚群细胞增多,未发现典型的TEMRA亚群。与PHA／IL-2相反,CD3／CD28抗体明显下调CCR5,并使早期感染者的病毒载量始终维持低于检出线水平（〈50IU／m1）。结论本研究以“Levine现象”为线索,验证和复制了诱导靶细胞抵抗和清除HIV-1感染的研究体系,为进一步探索新的防治HIV／AIDS的细胞分子机理奠定了基础。     

Low T cell reactivity to combined CD3 plus CD28 stimulation is predictive for progression to AIDS: correlation with decreased CD28 expression

In 219 HIV-1-infected men of the Amsterdam cohort we measured CD4⁺ T cell numbers and in vitro T cell responses to CD3 MoAbs with or without CD28 costimulation and phytohaemagglutinin (PHA). The value of these markers was estimated for disease progression within 4 years. CD28 expression on T cells has been related to T cell responses. CD28 costimulation considerably enhanced T cell reactivity (≈8–10-fold) with lower coefficients of variation compared with reactivity to CD3 MoAb alone (median 5 versus 20). T cell reactivity to CD3 plus CD28 MoAb was decreased during HIV-1 infection and was besides CD4⁺ T cell numbers the only independent predictor for progression to AIDS. Compared with the group with high CD4⁺ T cell numbers the relative risk (RR) for the group with intermediate levels was 2.28, with low levels 5.20. In the groups with intermediate and low CD3 plus CD28 responses the RR was 2.04 and 4.16, respectively. The combined RR for both was 4.65 and 21.63. The independence of this marker was confirmed when the group with low CD4⁺ T cell numbers was subdivided into groups with high, intermediate and low T cell responses. The expansion of CD8⁺CD28⁻ T cells was already apparent in HIV⁻ homosexual men, but CD8⁺CD28⁺ T cells specifically decreased in patients with AIDS. CD28 expression on T cells correlated moderately with T cell responses to CD3 plus CD28 MoAb. T cell reactivity to CD3 MoAb in the presence of CD28 MoAb is a stronger prognostic marker than T cell reactivity to CD3 MoAb alone.     

DNA甲基化在急性冠脉综合征患者CD4+CD28-T细胞CD28表达缺失中的作用

目的 通过研究急性冠脉综合征(acute coronary syndrome,ACS)患者外周血CD4+T细胞CD28 mRNA水平和CD28基因启动子调节序列的甲基化状态,旨在探讨DNA甲基化在ACS患者CD4+CD28-T细胞CD28表达缺失中的作用.方法 免疫磁珠分离CD4+T细胞经逆转录后,实时定量PCR(real time-PCR)技术检测CD4+T细胞CD28mRNA的表达水平,亚硫酸氢钠测序检测CD28基因启动子调节序列的甲基化状态.结果 与正常对照组相比,ACS患者CD4+T细胞CD28mRNA表达水平显著减低,差异具有统计学意义[正常对照组比ACS组:(1.066±0.162)比(0.401±0.069),P<0.05].CD28基因启动子区域的甲基化水平显著增高,差异有统计学意义[正常对照组比ACS组:(24.47±3.17)%比(43.33±1.52)%,P<0.05].CD28基因启动子区域DNA甲基化水平与CD28mRNA表达水平呈显著负相关(P=0.01,r=-0.579).结论 ACS患者CD4+T细胞CD28基因启动子区域高甲基化调控了CD28基因转录抑制.DNA甲基化参与了CD4+CD28-T细胞的形成.     

CD28 Superagonist D665-mediated activation of mouse regulatory T cells maintains their phenotype without loss of suppressive quality

Regulatory T cells (Tregs) maintain immune homeostasis by regulating the activation of other immune cells. Preclinical studies show that the infusion of Tregs can promote immunological tolerance to allografts and prevent or cure multiple autoimmune diseases. However, Treg therapy is limited by high numbers of cells required to induce tolerance. In this study, we aimed at improving the in vitro expansion of sort purified mouse Tregs using the CD28 Superagonist (CD28-SA) D665 and comparing it to the conventional expansion using anti-CD3/anti-CD28 Dynabeads®. CD28-SA—stimulated Tregs expanded more than Dynabead®-stimulated Tregs while maintaining their phenotype by expressing the same level of CD4, CD25 and Foxp3. CD28-SA—expanded Tregs produced comparable amounts of IL-10 and TGFβ while showing a slightly superior suppressive capacity compared to Dynabead®-stimulated Tregs. Thus, stimulating murine Tregs with the CD28-SA is a promising alternative since it maintains their suppressive capacity without altering their phenotype and yields a higher fold expansion within 14 days.