流式细胞术检测CFSE标记人T细胞亚群增殖反应

目的探讨应用流式细胞术和活细胞荧光染料CFSE检测T淋巴细胞各亚群增殖反应的方法学。方法人外周血单个核细胞（PBMC）经CFSE染色后,分别用植物凝血素（PHA）、CD3 mAb和结核杆菌抗原（Mtb-Ag）刺激,加IL-2扩增后,用流式细胞术检测活化增殖后T细胞各亚群的比例,并用ModFit软件分析各亚群的增殖动力模型。结果PHA和CD3 mAb主要活化总T细胞,CD8^＋T细胞的增殖优于CD4^＋T细胞,但CD4^＋T细胞前4代细胞明显多于CD8^＋T细胞。Mtb-Ag主要刺激γδT细胞增殖。结论以CFSE标记淋巴细胞,结合流式细胞术可有效检测出不同T细胞亚群对不同刺激剂的增殖反应以及增殖动力学变化。     

Delineation of chicken thymocytes by CD3-TCR complex, CD4 and CD8 antigen expression reveals phylogenically conserved and novel thymocyte subsets.

To further define the relationship between thymocyte subsets and their developmental sequence, multi-parameter flow cytometry was used to determine the distribution of the CD3-TCR complex and the accessory molecules CD4 and CD8 on chicken thymocytes. As in mammals, adult thymocytes could be subdivided into CD3-, CD3lo, and CD3hi staining populations. CD4 and CD8 distribution on such populations revealed the presence of CD3-CD4+CD8- and CD3-CD4-CD8+ thymocytes, putative precursors to CD4+CD8+ cells, detectable in the adult and at high frequency during ontogeny. Of particular interest was the existence of CD3lo expression on CD4+CD8- and CD4-CD8+, and in some instances, on CD4-CD8- thymocytes. Such phenotypes are not easily detectable in the mammalian thymus but were readily observed in both adult and embryonic chicken thymus from 16 days of embryogenesis. Further analysis of the TCR lineage of these CD3lo cells revealed that they were essentially all of the alpha beta TCR type. Mature CD3hi thymocytes were found within the CD4+CD8+ and CD4+CD8- and CD4-CD8+ subsets. Both alpha beta and gamma delta TCR lineage thymocytes were detected within all CD4- and CD8-defined subsets, thus identifying novel thymocyte subsets in the chicken thymus, namely alpha beta TCR+CD4-CD8- and gamma delta TCR+ CD4+CD8- cells. Hence, this analysis of chicken thymocytes, while confirming the phylogenically conserved nature of the thymus, has revealed novel T cell subsets, providing further insight into the complexity of mainstream thymocyte maturation pathways.     

In‐utero coxsackievirus B4 infection of the mouse thymus

Type B coxsackievirus (CV‐B) infections are involved frequently in the triggering of several autoimmune diseases such as myocarditis, dilated cardiomyopathy, pericarditis, pancreatitis, type 1 diabetes, encephalitis, thyroiditis or Sjögren's syndrome. Serological and virological evidence suggests that maternal infections during pregnancy can play a role in the appearance of these diseases in offspring. The current study aims to explore the effect of an in‐utero CV‐B infection on the fetal thymus, the central site for programming immunological self‐tolerance. In this perspective, female Swiss albino mice were inoculated intraperitoneally or orally with the diabetogenic CV‐B4 E2 strain at gestational days 10 or 17. Offspring were killed at different post‐inoculation times, and their thymuses were analysed for evidence of infection and alterations in thymic T cell subsets. In‐utero CV‐B infection of the thymus was demonstrated during the course of vertical transmission, as attested by viral RNA and infectious virus detection in most analysed samples. No histopathological changes were evident. Thymic T cells were not depleted, despite being positive for viral RNA. As evidenced by flow cytometry analysis, CV‐B infection of the fetal thymus induced significant changes of thymic T cell populations, particularly with maternal inoculation at gestational day 10. Altogether, these findings suggest that CV‐B infection of the fetal thymus may play an important role in the genesis of autoimmune diseases.     

Onset of promiscuous gene expression in murine fetal thymus organ culture

T-cell differentiation and induction of tolerance to self-antigens occurs mainly in the thymus. Thymic stromal cells, specifically medullary thymic epithelial cells, express a diverse set of genes encoding parenchymal organ-specific proteins. This phenomenon has been termed promiscuous gene expression (PGE) and has been implicated in preventing organ-specific autoimmunity by inducing T-cell tolerance to self antigens. Early thymopoiesis and the critical factors involved in T-cell differentiation can be reproduced in vitro by murine fetal thymus organ culture (FTOC), which mimics the natural thymic microenvironment. To evaluate the occurrence of PGE in FTOC, gene expression profiling during in vitro thymic development in BALB/c mice was performed using a set of nylon cDNA microarrays containing 9216 sequences. The statistical analysis of the microarray data (sam program) revealed the temporal repression and induction of 57 parenchymal and seven lymphoid organ-specific genes. Most of the genes analysed are repressed during early thymic development (15-17 days post-coitum). The expression of the autoimmune regulator (AIRE) gene at 16 days post-coitum marks the onset of PGE. This precedes the induction of parenchymal organ genes during the late developmental phase at 20 days post-coitum. The mechanism of T-cell tolerance induction begins during fetal development and continues into adulthood. Our findings are significant because they show a fine demarcation of PGE onset, which plays a central role in induction of T-cell tolerance.     

T淋巴细胞亚群及其细胞因子在子痫前期患者的表达及意义

目的通过检测T淋巴细胞亚群及其所分泌的细胞因子IL-10、TNF-α在子痫前期患者外周血及胎盘中的变化规律及其相关性,探讨其与子痫前期发病的关系。方法取60例孕妇(正常晚孕组20例;子痫前期组40例,其中轻度20例,重度20例)外周血,分别检测T淋巴细胞亚群比例及其细胞因子IL-10、TNF-α的水平;分娩后检测胎盘组织中的IL-10、TNF-α的表达。结果①轻度子痫前期组胎盘IL-10、TNF-α的表达强度与对照组相比均无显著差异(P>0.05),而重度子痫前期组IL-10表达强度显著降低(P<0.05),且与子痫前期病情呈负相关(rs=-0.342P=0.009);TNF-α表达强度显著升高(P<0.05),且表达强度与子痫前期病情呈正相关(rs=0.349P=0.007)。②子痫前期组IL-10外周血中含量明显低于对照组(P<0.05),其中重度子痫前期组IL-10外周血中的含量比轻度子痫前期者降低(P<0.05),差异有显著性;而TNF-α的含量明显升高(P<0.05)。③子痫前期组血清CD4 、CD8 的细胞百分比与对照组相比无显著差异,但CD4 /CD8 比例上升明显,两者比较有显著性差异(P<0.05)。子痫前期组中重度子痫前期者血清CD4 /CD8 比例比轻度子痫前期者血清CD4 /CD8 比例上升,且差异有显著性(P<0.05)。结论T淋巴细胞亚群及其所分泌的细胞因子的变化可能与子痫前期的发病中起着重要作用,且与病情密切相关。     

CD95 expression and function on lymphocyte subpopulations in common variable immunodeficiency (CVID); related to increased apoptosis.

Apoptosis is now recognized as a central process of development and disease, and it has been proposed as one of the mechanisms that may account for the lymphopenia seen in some diseases. In this study we measured spontaneous apoptosis and CD95 expression on different cell subpopulations from CVID patients, using flow cytometric techniques. We divided our patients into two groups according to their CD4+ and CD4+CD45RA+ cell counts. Our results clearly show increased spontaneous apoptosis and CD95 expression on the CD4+ and CD4+CD45RA+ subsets from lymphopenic CVID patients compared with normal subjects and disease controls. Interestingly, our lymphopenic CVID patients presented a profound reduction in absolute counts, mainly affecting the CD4+CD45RA+ subpopulation. We also found a statistically significant direct correlation between absolute numbers of CD4+CD45RA+ T cells and spontaneous apoptosis on the same subset in CVID patients, but attempts to induce CD95-mediated apoptosis were unsuccessful despite increased CD95 expression on CD4+ T cells. These findings suggest that apoptosis could be one of the mechanisms implicated in the significant lymphopenia present in these patients.     

Mechanisms of immune tolerance induction through the thymic expression of a peripheral tissue-specific protein

A major process through which the immune system becomes tolerantto self proteins involves the deletion of self reactive cellsin the thymus. However, T cells reactive to peripheral tissue-specificproteins can escape this deletion and become tolerized in theperiphery by a variety of mechanisms. We report here, contraryto expectation, that the pancreas-specific protein, elastaseI, is also expressed at a low level in the thymus, and thatthis thymic expression contributes to tolerance induction. Tostudy the mechanism of this tolerance induction, we utilizeda double transgenic mouse model. In these mice the expressionof a model protein, SV40 T antigen, is directed by the elastaseI promoter and hence parallels elastase I expression in thepancreas and thymus. These mice were crossed with mice transgenicfor a TCR specific for T antigen, so the majority of thymocytesand T cells in these mice express the transgene. In double transgenicmice we find that thymic expression of T antigen results inanergic thymocytes which also show a reduction of T_h1 activitywith no decrease in T_h2 activity. These functional characteristicspersist in peripheral T cells, but there is also a depletionin the number of T antigen reactive T cells In lymph nodes.Chimeras were constructed which directly demonstrated that thethymus is the site of tolerance induction and that the tolerizingelement is thymic epithelium. We propose that the loss of T_h1activity as a consequence of the thymic epithelium being encounteredby tissue-specific proteins results in the functional tolerizationof CTL in vivo, despite the fact that CTL are fully functionalin vitro. In this way autoimmune destruction is contained. Thymicexpression of peripheral proteins may therefore be an additionalway in which tolerance to peripheral proteins can be achieved.     

Coxsackievirus B4 infection of murine foetal thymus organ cultures

The infection of foetal thymus with coxsackievirus B4 (CV-B4) E2 has been studied ex vivo by using CD-1 mice on foetal day 14, as a ready source of organs for experimentation to investigate the hypothesis of the role of thymic viral infections in the pathogenesis of type 1 diabetes. The replication of CV-B4 E2 in murine foetal thymus organ cultures has been demonstrated by evaluating the levels of positive- and negative-stranded viral RNA in cells by using a real-time quantitative RT-PCR method and by determining titres of infectious viral particles in culture supernatants for 7 days post-infection (p.i.). Staining of tissue sections with an anti-cytokeratin antibody and haematoxylin-eosin showed that CV-B4 infection had no visible effect on cell survival and organ integrity. Cell counts in mock- and virus-infected foetal thymus organ cultures increased from day 1 through day 7, and live cell numbers were comparable in both conditions as shown by Trypan blue exclusion test and 7-amino-actinomycin D staining of thymocytes. Compared with controls on day 7 p.i., cytofluorometric analyses on cells from CV-B4 E2-infected foetal thymus organ cultures displayed a marked increase in the percentage of the most immature CD3(-)CD4(-)CD8(-) thymocytes, and a decrease in the percentage of immature CD3(-)CD4(+)CD8(+) cells, together with an increase in the percentage of mature CD3(+)CD4(+) and CD3(+)CD8(+) cells. These data show that CV-B4 E2 disturbs T-cell maturation and differentiation processes in infected murine foetal thymus organ cultures and provide evidence of a suitable system to investigate the effect of viruses in T-cell differentiation.     

The effects of interleukin 2 on early and late thymocyte differentiation in foetal thymus organ culture

The effects of interleukin 2 (IL-2) on in vitro T cell development in organ cultures of day 14 foetal mouse thymus were investigated. Over a 12 day culture period IL-2 was found to inhibit the development of each of the major thymocyte subpopulations, defined by CD4 and CD8 expression. Since each subpopulation was reduced in number, a common precursor to these subsets was thought to be inhibited by IL-2. Indeed, subsequent analyses of subsets of CD4- CD8- cells, characterized by expression of HSA, Pgp-1, and IL-2R, demonstrated that CD4- CD8- cells expressing IL-2R and their postulated progeny were reduced in IL-2-treated cultures. The number of cells reputed to be the immediate precursor of CD4- CD8- IL-2R+ cells, i.e. CD4- CD8- Pgp-1+IL-3R- cells, was not change by treatment with IL-2. Interestingly, however, numbers of the most immature subset of CD4- CD8- cells, identified as having the HSA1oPgp-1+IL-2R- and CD3- phenotype, increased in IL-2-treated cultures and was the only population of cells to do so. We also document the failure to detect any LAK cell activity against syngeneic thymocytes in IL-2-treated cultures and therefore hypothesize that the inhibition of T cell differentiation in these cultures is due to an arrest in differentiation of CD4- CD8- cells bearing the IL-2R.     

Alterations in the thymocyte phenotype of EphB-deficient mice largely affect the double negative cell compartment

In the present study, we have analysed the phenotype of EphB2 and/or EphB3 deficient thymocytes confirming and extending previous studies on the role of this family of molecules in T-cell differentiation. In all mutant thymuses statistically significant reduced cell contents were observed. This reduction of thymic cellularity correlated with increased proportions of apoptotic cells, largely both double negative (DN; CD4- CD8-) and double positive (CD4+ CD8+) cells, and decreased proportions of DN cycling cells. Adult deficient thymuses also showed increased proportions of DN cells but not significant variations in the percentages of other thymocyte subsets. In absolute terms, the thymocyte number decreased significantly in all thymocyte compartments from the DN3 (CD44- CD25+) cell stage onward, without variations in the numbers of both DN1 (CD44+ CD25-) and DN2 (CD44+ CD25+) cells. Remarkably, all these changes also occurred from the 15-day fetal EphB2 and/or EphB3 deficient mice, suggesting that adult phenotype results from the gradual accumulations of defects appearing early in the thymus ontogeny. As a reflection of thymus condition, a reduction in the number of T lymphocytes occurred in the peripheral blood and mesenteric lymph nodes, but not in spleen, maintaining the proportions of T-cell subsets defined by CD4/CD8 marker expression, in all cases.     

Expression of genes encoding the pre-TCR and CD3 complex during thymus development

The mature TCR is composed of a clonotypic heterodimer (ßor) associated with the invariant CD3 components (, , and ).There is now considerable evidence that more immature formsof the TCR-CD3 complex (consisting of either CD3 alone or CD3associated with a heterodimer of TCR ß and pre-T)can be expressed at the cell surface on early thymocytes. Thesepre-TCR complexes are believed to be necessary for the orderedprogression of early T cell development. We have analyzed indetail the expression of both the pre-TCR and CD3 complex atvarious stages of adult thymus development. Our data indicatethat all CD3 components are already expressed at the mRNA levelby the earliest identifiable (CD4¹⁰) thymic precursor. In contrast,genes encoding the pre-TCR complex (pre-T and fully rearrangedTCR ß) are first expressed at the CD44¹⁰CD25⁺CD4^–CD8^–stage. Detectable surface expression of both CD3 and TCR ßare delayed relative to expression of the corresponding genes,suggesting the existence of other (as yet unidentified) componentsof the pre-TCR complex.     

Interleukin-4 induces expression of the CD45RA antigen on human thymocyte subpopulations

Interleukin-4 (IL-4) is a multifunctional lymphokine which promotes the growth and/or maturation of multiple cell types. We have examined the ability of IL-4 to promote the phenotypic maturation of subsets of human thymocytes. When cultured in serum-free medium supplemented with recombinant IL-4, a subset of immature CD3-CD45RA- human thymocytes ceased to express the CD1 common thymocyte antigen and acquired phenotypic features characteristic of relatively mature thymocytes, such as high-density expression of the CD3 antigen and de novo expression of the CD45RA isoform of the common leukocyte antigen family. These changes, which were not seen in cells cultured in medium alone, occurred over an 8-9 day period and were accompanied by a significant increase in cell size. The CD45RA+ cells that derived from these immature CD3-CD45RA- precursors were mainly CD4-CD8- or CD8+ cells, and a significant proportion of these cells expressed the T cell receptor delta chain. IL-4 also increased expression of the CD45RA antigen on the more mature CD3+ thymocyte population. However, the CD45RA+ cells derived from IL-4 stimulated CD3+ thymocyte precursors expressed either the CD4 or the CD8 antigen, and virtually all expressed alpha/beta TCR chains. Studies of cell viability and cell growth indicated that these findings were due to direct changes in the phenotype of responsive cells rather than the growth or selective survival of a small number of mature thymocytes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Structural control of poly(2-hydroxyethyl methacrylate)-graft-polyamine copolymers for differential retention of rat lymphocyte subpopulations

Poly(2-hydroxyethyl methacrylate)-graft-polyamine copolymers (HA copolymers) of varying composition and chain length of the polyamine graft were prepared by radical copolymerization of 2-hydroxyethyl methacrylate with a given quantity of polyamine macromonomer having a controlled molecular weight, and their interaction with lymphocyte subpopulations (B and T cells) was estimated using a column method. From these results, it was revealed that the most suitable molecular structure of HA copolymers for separating lymphocyte subpopulations is that of an HA copolymer with 13 wt% of polyamine graft with a chain length 3000-6600 in molecular weight. It is concluded that the retention process of lymphocytes on the HA graft copolymers is driven primarily by ionic interactions between the protonated amino groups and the cells. However, the mode of the polyamine microdomain structure, that is the distribution of protonated amino groups, and the conformation of the polyamine chains, which varies with the chain length of the HA copolymer, are also important factors in determining differential lymphocyte retention.     

Separation and isolation of lymphocyte subpopulations of different affinity for the antigen

In order to separate, isolate, and determine the number and distribution of the subpopulations of lymphocytes of diverse affinities that are present in an immune response toward a single hapten, anti-trinitrophenyl (TNP) lymphocytes from immunized animals were purified by cell chromatography. Non-adherent spleen cells were passed through a column consisting of TNP-substituted polyacrylamide beads. The retained cells were eluted by applying a linear concentration gradient of TNP-lysine. Elution profiles having a limited number of peaks were obtained in all cases. The avidity of the cells in each fraction was measured by inhibition of formation of immune rosettes by free hapten. Results showed that each peak was located along the gradient according to its affinity since there was a direct correlation between the affinity and the concentration of hapten needed for the elution. The cells in each peak appeared to belong to a homogeneous subpopulation as shown by the slope of the curves obtained in the determination of avidity, suggesting that each peak corresponded to one expanded clone.     

The role of thymus in the aging of Th cell subpopulations and age-associated alteration of cytokine production by these cells

Mouse CD4⁺ T cells were subdivided into two subpopulations,naive (CD44^low CD45RB^high) and memory (CD44^highCD45RB^low) Tcells, by flow cytometric analysis. Examination of spleen andperipheral blood of C57BL/6 mice of various ages revealed thatthere was a reciprocal ageassociated change in these two subpopulations,i.e. naive T cells predominant in young mice decreased withage, while memory T cells increased. In order to investigatethe role of the thymus in the age change of naive and memoryT cells, we employed two experimental systems: radiation bonemarrow chimeras constructed between young and old mice, andgrafting of young or old thymus into nude mice. Data from thesetwo experiments suggested that the young thymus has a greaterability to provide naive T cells than the old thymus, whilethe old thymus favors the maintenance of memory T cells ratherthan naive T cells. In reference to cytokine production by enrichednaive and memory T cells, young naive T cells produced mainlyIL-2 and young memory T cells mainly IL-4. On the other hand,in old mice, memory T cells produced twice as much IL-2 thannaive T cells, although the level was significantly lower thanthat of young mice. In addition, old naive T cells producedtwice as much IL-4 than old memory T cells. These results suggesteda distinct age change in the profile of cytokine productionand functional heterogeneity of two T_h cell subpopulations.     

Monocyte chemoattractant protein 1 (MCP‐1/CCL2) contributes to thymus atrophy in acute myeloid leukemia

Recent studies on acute myelogenous leukemia (AML) patients have revealed the existence of T‐cell immunodeficiencies, characterized by peripheral T lymphocytes that are unable to interact with blasts, reduced thymic emigrants and oligoclonal restricted repertoires. These observations suggest that there is a profound thymic dysregulation, which is difficult to study in AML patients. Using the C1498 AML mouse model, we demonstrated that leukemia development was associated with thymus atrophy, which was defined by abnormal organ weight and reduced cellularity. In addition, we observed a dramatic loss of peripheral CD4⁺ and CD8⁺ T‐cell numbers with increased frequencies of CD4⁺FoxP3⁺ regulatory and activated/memory T cells. Investigating the mechanisms leading to this atrophy, we observed a significant accumulation of the monocyte chemoattractant protein 1 (MCP‐1/CCL2) in thymi of leukemic mice. Treatment of AML‐bearing animals with a blocking anti‐CCL2 antibody revealed a lower tumor burden, augmented antileukemic T‐cell responses, and improved survival rate compared to nontreated mice. These results were not observed when neutralization of CCL2 was performed in thymectomized mice. Altogether, we show that the CCL2 protein participates in thymic atrophy in AML mice, and this could have important implications for future immunotherapeutic strategies.     

Limited development capacity of the earliest embryonic murine thymus

Previous studies have demonstrated that murine thymus separates from the pharynx during 11.5–12 days of gestation, and that the proliferation of thymic cells starts at this age. We characterized embryonic day 12 thymus in terms of the surface phenotype of the thymus cells, the function of the lobe in supporting T cell development in organ culture, and the precursor activity of the thymus cells in a mixed culture with deoxyguanosine-treated lobes. The phenotype of the major population of embryonic day 12 thymus cells was HSA⁺, CD44⁺, c-kit⁺, Thy-1^?, CD25^?, CD4^?, CD8^?, TcR^?, and Sca-1^?. In organ culture of embryonic day 12 thymus lobes, most of the lobes did not develop well and failed to generate CD4⁺CD8⁺, CD4⁺CD8^?, or CD4^?CD8⁺ cells, even when embryonic day 14 thymus cells were added. However, thymus cells on embryonic day 12 contained T cell precursors that developed into mature T cells in co-culture with deoxyguanosine-treated fetal thymic lobes. The majority of the stromal cells in deoxyguanosine-treated embryonic day 14 thymus lobes expressed the surface molecules I-A and H-2D, whereas these cells in embryonic day 12 thymus lobes were negative for these surface molecules. Thus, our findings suggest that the embryonic day 12 thymus lobe contains T cell precursors, but that the undeveloped thymic stromal cells are insufficient to support full T cell development.     

Loss of Ly-6A.2 expression on immature developing T cells in the thymus is necessary for their normal growth and generation of the Vbeta T-cell repertoire

Stage-specific expression of a number of cell-surface and signaling proteins is critical for normal development of T cells in the thymus. Equally important may be the loss of expression/signaling of developmentally regulated proteins for proper transitioning of developing T cells into thymic subsets. Ly-6A.2 exhibits a regulated pattern of expression on T cells maturing in the thymus, and dysregulating its expression results in arrest of developing T cells within the CD3-CD4-CD8- triple negative (TN) stage where the normal expression of Ly-6A.2 is extinguished. To further characterize the mechanisms underlying this block, we examined whether cell signaling and/or cell adhesion properties of the Ly-6A.2 molecule influenced the block in T-cell development. Analysis of bone marrow chimeras generated by injecting CFSE-labeled Ly-6A.2 transgenic bone marrow cells into irradiated syngeneic non-transgenic mice revealed normal trafficking of developing T cells from the cortex into the medulla. Production of LAT but not p56lck was diminished in CD4-CD8- DN cells from Ly-6A.2 dysregulated mice when compared with control littermates. Dysregulated expression of Ly-6A.2 did not suppress endogenous TCR-Vbeta expression. Finally, dysregulated expression of Ly-6A.2 enhanced apoptosis of an immature CD4+CD8+ (DP) subset of developing cells and altered the selected TCR-Vbeta repertoire. Taken together, these observations indicate that the termination of Ly-6A.2 expression and signaling within the CD4-CD8-CD3- subset of developing T cells is an important checkpoint during normal thymic development.