IL—6诱导人骨髓瘤细胞表达CD45

目的：研究髓瘤细胞系Sko-007中IL－6信号途径活化与CD45诱导表达之间的关系。方法：首先采用凝胶阻滞电泳（electrophoretic mobility shift assay,EMSA)方法检测参与IL－6信号转导功能的转录因子STAT3和NF－IL－6在Sko-007细胞中的诱导活化情况并确定该细胞中IL－6信号转导途径;进而采用RT－PCR和FACS方法检测CD45mRNA和蛋白在IL－6刺激作用下的诱导表达情况;最后采用以上两种方法观察CD45诱导表达与I－6信号途径活化之间的关系。结果：①两种主要的IL－6信号转导途径JAK／STAT和Ras/NF-IL-6都能够在Sko-007细胞中诱导激活;②CD45mRNA和蛋白的表达量在IL－6刺激作用下明显增加;③STAT3反义表达质粒导入Sko-007细胞后JAK／STAT途径活化信号减弱,同时CD45mRNA诱导表达量下降。结论：Sko－007细胞中JAK／STAT途径的诱导激活介导了CD45的诱导表达。     

浆细胞CD45和CD31的表达与多发性骨髓瘤细胞分化程度的关系

目的: 了解反映多发性骨髓瘤(MM)细胞生物学行为的免疫标记在骨髓不同阶段浆细胞中的表达情况,为临床调整治疗策略和判断疾病病程及预后提供依据。方法: 用流式细胞术检测MM患者及对照组浆细胞表面相关分化抗原的表达情况,分析其在良、恶性浆细胞表达的差异,及其与原始浆细胞比例的相关性。结果: MM患者浆细胞CD45和CD31表达率低于对照组浆细胞; MM细胞 CD45和CD31的表达率与原始浆细胞比例呈负相关;CD45表达与CD31表达呈现正相关。结论: 浆细胞CD45和CD31的表达率与MM细胞的分化程度呈正相关,其表达可能与MM的疾病进展有一定关系。     

A model retinal interface based on directed neuronal growth for single cell stimulation

In this work, we use cell micropatterning technologies to direct neuronal growth to individual electrodes, and demonstrate that such an approach can achieve selective stimulation and lower stimulation thresholds than current field-effect based retinal prostheses. Rat retinal ganglion cells (RGCs) were purified through immunopanning techniques, and microcontact printing (μCP) was applied to align and pattern laminin on a microelectrode array, on which the RGCs were seeded and extended neurites along the pattern to individual electrodes. The stimulation threshold currents of RGCs micropatterned to electrodes were found to be significantly less than those of non-patterned RGCs over a wide range of electrode-soma distances, as determined with calcium imaging techniques. Moreover, the stimulation threshold for micropatterned cells was found to be independent of electrode-soma distance, and there was no significant effect of μCP on cell excitability. The effects of additional stimulation parameters, such as electrode size and pulse duration, on threshold currents were determined. The stimulation results quantitatively demonstrate the potential benefits of a retinal prosthetic interface based on directed neuronal growth.     

Inhibition of thymopoiesis of CD34+ cell maturation by HIV-1 in an in vitro CD34+ cell and thymic epithelial organ culture model

The mechanisms by which HIV-1 affects thymopoiesis were determined by preincubating CD34+ cells or cultured thymic epithelial (CTE) cells with lymphotropic (T-) and monotropic (M-) strains of HIV-1 in an in vitro CTE organ and CD34+ cell coculture model that allows for analysis of development of thymocytes and mature T cells. When purified CD34+ cells were precultured with either T- or M-tropic strains of HIV-1, thymopoiesis was impaired in a two-week coculture manifested by decreased cell number of thymocytes generated. However, the percentages of thymocyte subpopulations were comparable to control uninfected cocultures. Furthermore, HIV infection of thymocytes was predominantly observed in the CD44+CD3- population. However, in a four-week coculture experiment, HIV infection and depletion of more mature thymocytes were also observed. When CTE cells were preincubated with T- and M-tropic strains of HIV before addition of CD34+ cells, the number of thymocytes and subpopulations of thymocytes at early and later stages of maturation were markedly decreased. Furthermore, CD34+ and CD44+CD3- cells become HIV-infected. In summary, HIV-1 infection inhibited thymocyte maturation at early stages of thymocyte maturation CD44+CD25-CD3-. In addition, HIV also depleted later stages of CD4+ thymocyte subpopulations.     

Differential effects of CD45 CD45R and CD45R0 monoclonal antibodies in modulating human B cell activation.

We have examined the effect of monoclonal antibodies (MoAbs) to different epitopes of the leucocyte common antigen (LCA), CD45, on anti-human immunoglobulin-primed B cell activation. Binding of MoAbs to restricted epitopes present on CD45 glycoproteins of 180 kD and 220 kD (designated CD45R0 and CD45R, respectively) was found to promote B cell proliferation in the presence of T cells. CD45 MoAbs reactive with 'public' determinants on all four constituent members of the LCA family (180, 190, 205, and 220 kD) had either little effect or inhibited the basal B cell response to anti-immunoglobulin priming. Simultaneous immunofluorescent analysis of 5-bromodeoxyuridine incorporation and the expression of CD19 (B cell specific) or CD2 (T cell specific) identified the majority of responder cells as B lymphocytes. CD45R MoAbs significantly enhanced the B cell response to sub-optimal concentrations of interleukin-2. CD45 and CD45R0 MoAbs failed to elicit a similar response. Antibody to the interleukin-2 receptor (anti-Tac) partially blocked the CD45R-driven, T cell-dependent B cell proliferation.     

An agonist anti-human CD40 monoclonal antibody that induces dendritic cell formation and maturation and inhibits proliferation of a myeloma cell line

CD40, a 48-50 KD cell membrane molecule, member of the nerve growth factor receptor and tumor necrosis factor receptor superfamily, is an important costimulatory molecule during the immune response. Anti-CD40 monoclonal antibody (MAb) has been shown earlier to costimulate with IgM or phorbol esters resting B cells to proliferate, differentiate, secrete immunoglobulins, and switch isotype. Here we report on an agonistic mouse anti-human CD40 MAb 5C11. The specificity of this MAb was verified by flow cytometry, Western blotting, and competition with anti-CD40 MAb 89. We studied the effects of MAb 5C11 on a multimyeloma cell line, XG2, that expresses the CD40 antigen strongly and found that this MAb caused the homotypic aggregation of XG2, strongly suppressed XG2 proliferation, and led to its apoptosis after 24 hr of treatment. Interestingly, MAb 5C11 also triggered the generation, proliferation, and maturation of dendritic cells from peripheral blood monocytes, either by itself or in combination with GM-CSF and IL-4.     

CD45RO and CD45RA positive cell populations in idiopathic membranous and IgA glomerulopathy.

AIMS: To immunophenotype and quantitate glomerular and interstitial inflammatory cells in cases of idiopathic membranous and IgA glomerulopathy; to correlate cell numbers with aspects of clinical data and renal function. METHODS: Routine indirect immunoperoxidase staining was performed on frozen section renal biopsy specimens for T and B lymphocyte related antigens, macrophages and MHC class II antigens. Double immunohistochemical staining was performed to identify CD45RO+ and CD45RA+ cells. RESULTS: In IgA glomerulopathy correlations were found relating interstitial cell numbers to creatinine concentration at biopsy (CD45RO+ and CD45RA+ cells) and follow up creatinine concentration (CD3+, CD4+, CD8+, CD45RO+, and CD45RA+ cells). Also in IgA glomerulopathy mean arterial pressure at biopsy correlated with interstitial cell numbers and most recent follow up creatinine concentration. There were no correlations between glomerular inflammatory cells and renal function in either disease. Double staining showed that although most glomerular CD45RO+ and CD45RA+ cells were macrophages, positive cells in the interstitium were lymphocytes. The interstitial CD45RO+:RA+ ratio in normal renal biopsy specimens was approximately 5:1; for IgA glomerulopathy it was 1.5 and was 1.0 in idiopathic membranous glomerulopathy. CONCLUSIONS: This study demonstrates that interstitial, and not glomerular, inflammatory cell numbers correlate with renal function in primary glomerular disease and that double staining is necessary to interpret positive immunostaining for antigens located on more than one type of inflammatory cell. Detailed investigation of the interstitial CD45RO+ and CD45RA+ cells may give an insight into the pathogenesis of glomerular disease.     

A study of CD45RO, CD45RA and CD29 antigen expression on human decidual T cells in an early stage of pregnancy

The decidua is the place where the fertilized egg is implanted and where the immunocompetent cells of the mother come into direct contact with genetically disparate cells of the conceptus. Although the T cells in the decidua are exposed to fetal antigens, the fetus is not rejected by maternal immunocompetent cells. In the present study, we examined surface markers to determine whether the T cells in the human decidua are naive T cells without or memory T cells with a history of antigen stimulation. Although few T cells were present in the decidua, as compared to the peripheral blood, CD45RO⁺, CD29⁺ and CD45RA⁻ CD4⁺ T cells as well as CD45RO⁻, CD29⁺ and CD45RA⁻ CD8⁺ T cells, which are considered to be memory T cells, were in the majority, with only small numbers of CD45RO⁻, CD29⁻ and CD45RA⁺ CD4⁺ and CD8⁺ cells, which are naive T cells, present. Also, the decidual mononuclear cells secreted IL-2 and IL-4. Since IL-4 is secreted only by memory T cells, it is suggested that in the decidua memory T cells increase in number and secrete cytokines, thereby in some way influencing the phenomenon of fertility.     

CD45: new jobs for an old acquaintance

Identified as the first and prototypic transmembrane protein tyrosine phosphatase (PTPase), CD45 has been extensively studied for over two decades and is thought to be important for positively regulating antigen-receptor signaling via the dephosphorylation of Src kinases. However, new evidence indicates that CD45 can function as a Janus kinase PTPase that negatively controls cytokine-receptor signaling. A point mutation in CD45, which appears to affect CD45 dimerization, and a genetic polymorphism that affects alternative CD45 splicing are implicated in autoimmunity in mice and multiple sclerosis in humans. CD45 is expressed in multiple isoforms and the modulation of specific CD45 splice variants with antibodies can prevent transplant rejections. In addition, loss of CD45 can affect microglia activation in a mouse model for Alzheimer's disease. Thus, CD45 is moving rapidly back into the spotlight as a drug target and central regulator involved in differentiation of multiple hematopoietic cell lineages, autoimmunity and antiviral immunity.     

Expression in vivo of CD45RA,CD45RB and CD44 on T cell receptor-transgenic CD8+ T cells following immunization

We used mice transgenic for a major histocompatibility complex class I-restricted T cell receptor to study the changes of phenotype in vivo which follow priming by antigen of CD8 T cells. We show that following priming with peptide, CD44 on CD8 T cells is up-regulated. The change of phenotype was relatively stable, as primed CD8 cells isolated from thymectomized mice 6 weeks after priming still expressed increased levels of CD44. CD8 T cells in these mice are still responsive to peptide and could represent long-lived primed cells. No downregulation in vivo of the CD45RA or CD45RB isoforms was found, indicating that there is a differential regulation of the expression of CD44 and CD45RB by activated CD8 transgenic T cells. These results contradict earlier studies in vitro which showed that CD8 T cells which have been primed earlier belong to the CD45RA^? or CD45RB^? subset.     

A cell death pathway induced by antibody-mediated cross-linking of CD45 on lymphocytes

The protein tyrosine phosphatase CD45 is a highly expressed glycoprotein present on all nucleated cells of hematopoietic origin. To date, all the functions attributed to CD45 are inherently coupled to its phosphatase activity. For instance, the regulation of lymphocyte antigen receptor signaling is mediated through the dephosphorylation, and hence activation, of Src-family kinases by CD45. Moreover, signaling via cytokine receptors is negatively modulated by CD45 by dephosphorylation of Janus kinase family members. Recently, another function for CD45, unrelated to regulation of surface receptor signaling, has been unraveled. Specific engagement of CD45 by monoclonal antibodies at the surface of lymphocytes induced their death, through an alternative caspase-independent pathway. In striking contrast to all other previously reported functions for CD45, its phosphatase activity is completely dispensable for the induction of cell death. This article reviews the current knowledge on the death pathway triggered by CD45 ligation on lymphocytes. In an attempt to better elucidate the mechanism of cell death induction through CD45, we also provide original data regarding the susceptibility of various subsets of immature and mature T and B cells to death induced by CD45 engagement. The physiological significance and therapeutic potential of CD45-induced death are also discussed.     

A model research on AIDS diffusion based on cellular automaton

Acquired Immune Deficiency Syndrome (AIDS) has been one of the main public heath problems that the Chinese public is facing. In order to estimate and predict the development of the epidemic situation, we studied on cellular automaton with the mechanism and characteristics of AIDS, and sets up an AIDS model on the base of the principle of cellular automaton. By studying the model, we analyzed the segregation power and AIDS-immune persons' influence on the transmission of the diseases. Some estimations and predictions can be drawn by studying model parameters. The structure of the model is flexible, and so it can change control tactics during evolution. Traditional differential equation cannot come up to it under the circumstances. It serves as tool with a great significance to the control as well as the prevention of AIDS.     

CD45 isoforms in T cell signalling and development

The CD45 phosphotyrosine phosphatase is expressed on T cells as multiple isoforms due to alternative splicing. The panoply of isoforms expressed is tightly regulated during T cell development and on mature peripheral T cell subsets following activation. We describe the analysis of comparative CD45 isoform expression levels on thymic and T cell subsets from the C57BL/6 mouse. Only four isoforms were expressed at significant protein levels: CD45R0, CD45RB, CD45RBC and CD45RABC, although trace amounts of others may be present. The expression of CD45RBC was about nine-fold higher on CD8(+) than on CD4(+) peripheral T cells, whereas CD45R0 expression was higher on CD4(+) T cells. We provide a general overview of the current models that have been proposed to explain the molecular actions of the different CD45 isoforms. Achieving a thorough understanding of the biological reasons for the existence and tight regulation of CD45 isoform expression in immune cells remains one of the outstanding challenges in the CD45 research field.     

Effects of mu-specific antibodies on B cell growth and maturation

Over a wide range of concentrations affinity-purified rabbit anti-mouse mu chain antibodies, or their F(ab')2 fragments, inhibit the appearance of immunoglobulin-secreting cells (plaque-forming cells; PFC) in lipopolysaccharide-stimulated murine spleen cell cultures without affecting proliferation. Both IgM and IgG PFC are inhibited although the number of blasts bearing surface IgG remains unaltered. The IgM and IgG PFC response could be reconstituted to normal levels in cell cultures suppressed by mu-specific antibodies by the addition of supernatants from in vitro propagated helper T cell clones, or from EL4 lymphoma cells induced with phorbol ester. Interleukin 1-containing P388 supernatant, or recombinant DNA-derived murine interferon-gamma, did not reconstitute the PFC response in cell cultures suppressed by mu-specific antibodies, indicating that other factors are responsible for these effects. When spleen cell cultures, pre-activated with either lipopolysaccharide or monoclonal mouse mu-specific antibodies coupled to Sepharose, were exposed to EL4 supernatants in the presence of soluble mu-specific antibodies, maturation to secretion was inhibited while proliferation was not. The implications of these findings on assay systems for B cell growth and maturation factors are discussed.     

An agonist antibody specific for CD40 induces dendritic cell maturation and promotes autologous anti-tumour T-cell responses in an in vitro mixed autologous tumour cell/lymph node cell model

CD40-mediated interactions play an important role in the response to a variety of diseases, including cancer. Engagement of CD40 on antigen-presenting cells, namely dendritic cells (DC), by CD40L leads to maturation and up-regulation of co-stimulatory molecules B7.1 and B7.2 (CD80 and CD86). These molecules are requisite to subsequent antigen-specific activation of T cells. T-cell activation is a critical aspect of specific anti-tumour immune responses that have become the focus of a variety of cancer immunotherapy approaches. Clinical trials involving immunologic interventions have shown clinical responses confirming that the immune system can be harnessed for the treatment of cancer. However, the clinical response rate has been low, signifying the need for new immunotherapeutic strategies. To this end, an agonist antibody specific for CD40, CP-870,893, has been developed. A fully autologous mixed tumour cell/lymph node cell model was utilized to demonstrate that CP-870,893 promotes the responsiveness of lymph node-derived T cells to autologous tumour. Specifically, T cells from the tumour-draining lymph nodes are not responsive to autologous tumour cells; however, in the presence of CP-870,893, this unresponsiveness is reversed, as indicated by lymph node cell proliferation and cytokine secretion. Monocyte-derived DC treated with CP-870,893 consistently display a mature phenotype: up-regulation of CD80, CD83, CD86 and HLA-DR expression, increased Mip1alpha and IL-12 secretion, and the loss of exogenous antigen-presenting capability subsequent to treatment with the antibody. These data indicate that CP-870,893 binds to and activates DC, ultimately driving a specific anti-tumour T-cell response.     

A model for an Ascaris muscle cell

Muscle cells in the nematode Ascaris suum undergo bouts of oscillation in the behaving worm, these being correlated with progressing waves of contraction along the body of the worm. The bouts have three time scales: a rough period of 7-20 s, 10-20 short bursts of spikes within a bout, and three to eight spikes per burst. This paper has two aims: showing that there is consistency between measurements of individual currents and measurements on whole muscle cells, and creating a building block to eventually explain the locomotion in this 'simple' system. A realistic model for a single Ascaris suum muscle cell is developed using existing data from experiments which have established the types of ionic currents in the muscle cell and many of their kinetic properties. Numerical simulations are carried out. The model cell reproduces the two shorter time scales present. It has some robustness with regard to parameter changes, but also allows for the different numbers of spikes per burst seen in recordings from muscle cells. The third time scale, the length of a bout, may originate from some system effect, a combination of neural and stretch effects and possibly a secondary effect of the calcium-activated chloride channel.     

CD83 regulates splenic B cell maturation and peripheral B cell homeostasis

The central function of murine CD83 that is expressed on thymic epithelial cells is to induce the progression of double-positive thymocytes to single CD4-positive T cells. Several lines of evidence suggest an additional role for CD83 in the regulation of peripheral T and B cell responses. Here we show that CD83 is expressed by immature B cells and regulates their further maturation and survival in the periphery. Employing mixed bone marrow chimeras, we compare wild-type, CD83 over-expressing and CD83-deficient B cells within the same host. CD83 over-expression on the immature B cells themselves led to an accumulation of transitional B cells and a reciprocally reduced maturation of follicular B cells that was strictly correlated to the intensity of CD83 over-expression. The absence of CD83 on B cells resulted in a decreased maturation of marginal zone B cells and conferred a mild selection advantage for B cell survival in the periphery. Consenting with these findings, the over-expression of CD83 specifically and dose dependently interfered with homeostasis of B cells while T cell survival was not affected by CD83 over-expression over a period of 30 weeks. Taken together, our data suggest that CD83 negatively regulates B cell maturation and survival.     

Lymphocytic CD43 and CD45 bear sulfate residues potentially implicated in cell to cell interactions

CD43 is a major heavily glycosylated lymphocyte surface molecule. It has been shown to play an important role in lymphocyte activation and cell-cell interactions. Here we demonstrate that in human activated lymphocytes and CEM T cells, CD43 is a sulfated molecule. We also observed that CD45, another lymphocyte surface glycoprotein, is a sulfated molecule. ³⁵SO incorporation would thus appear to be an appropriate labeling method for CD43 and CD45 visualization. Moreover, we show that the level of cell surface protein sulfation can modulate CD43-mediated homotypic aggregation induced by CD43 monoclonal antibodies. It is well known that glycoprotein sulfation is required for various recognition phenomena. Since there are numerous potential sulfation sites on CD43 and CD45, these residues could play an important role in regulating cell-cell interactions.     

Biochemical association of CD45 with the T cell receptor complex: regulation by CD45 isoform and during T cell activation.

CD45 is the predominant transmembrane tyrosine phosphatase in lymphocytes and is required for the efficient induction of T cell receptor signaling and activation. However, the regulation of CD45 activity and substrate specificity are poorly understood. In the present study, we demonstrate a basal biochemical association of CD45 with the T cell receptor complex that is regulated in part by CD45 isoform expression. Further, maintenance of CD45/TCR association is differentially regulated following TCR ligation with peptide: a partial agonist peptide induces CD45/TCR dissociation while an agonist peptide promotes sustained association in a CD4-dependent manner. These data suggest that T cell receptor signaling pathways may be modulated by altering access of CD45 to TCR-associated substrates involved in T cell activation.     

Atopy, asthma, and experimental approaches based on the linear model of T cell maturation

The linear model of maturation of IFN-gamma-producing cells from a proliferative pool of type 2 cytokine-producing T cells represents a fundamental shift in interpreting how changes in cytokine production by T cell populations are regulated. A major tenet of this model is antigen-independent, bystander proliferation of type 2 T cells and their maturation to IFN-gamma+ cells. Both clinical observations and prevailing theories of immune system development in asthma are consistent with this highly interpretative in vitro model, which allows unambiguous characterization of the modulation of the intrinsic features of T cell proliferation and differentiation by environmental and genetic factors. Hypotheses based on the linear model of T cell maturation are readily testable and should lead to a greater understanding of not only allergen-specific responses, but also the non-specific, bystander effects associated with specific responses to allergens or pathogens. Topics to be discussed in the context of the linear model of T cell maturation in this review include: (1) allergic responses to an inciting allergen that may enhance sensitivity to subsequent yet different allergens; (2) dampening the preferential accumulation of type 2 T cells during a typical immune response against viral and bacterial pathogens; (3) allergen-independent sensitization in asthmatics: (4) the 'hygiene hypothesis' for the reported increased allergy development in industrialized countries; (5) elevated IFN-gamma levels in asthmatics, in addition to the expected high levels of type 2 cytokines; (6) testing the effects of inflammatory mediators, as well as various anti-inflammation therapies on T cell maturation; and (7) testing the influence of gene variation on T cell maturation.