Are the Mast Cells Antigen Presenting Cells?

Mast cells have an important role in allergic reactions secreting histamine and other mediators of immediate hypersensitivity. In the present study we evaluated major histocompatibility complex (MHC) class II antigen expression in mast cells and their possible role in antigen presentation. In rats, 10% of mast cells isolated from the pleural cavity expressed MHC class II antigen; after incubation with gamma interferon (INF) 80% of the cells were positive. These findings suggest that mast ceils, in addition to their secretory function in allergic reactions, may also function as antigen presenting cells.     

Mannose Receptor-Mediated Gene Delivery into Antigen Presenting Dendritic Cells

Dendritic cells are professional antigen presenting cells and are unique in their ability to prime naíve T cells. Gene modification of dendritic cells is of particular interest for immunotherapy of diseases where the immune system has failed or is aberrantly regulated, such as in cancer or autoimmune disease, respectively. Dendritic cells abundantly express mannose receptor and mannose receptor-related receptors, and receptor-mediated gene transfer via mannose receptor offers a versatile tool for targeted gene delivery into these cells. Accordingly, mannose polyethylenimine DNA transfer complexes were generated and used for gene delivery into dendritic cells. Mannose receptor belongs to the group of scavenger receptors that allow dendritic cells to take up pathogenic material, which is directed for degradation and MHC class II presentation. Therefore, a limiting step of transgene expression by mannose receptor-mediated gene delivery is endosomal degradation of DNA. Several strategies have been explored to overcome this limitation including the addition of endosomolytic components to DNA transfer complexes like adenovirus particles and influenza peptides. Here, we review the current understanding of mannose receptor-mediated gene delivery into dendritic cells and discuss strategies to identify appropriate endosomolytic agents to improve DNA transfer efficacy.     

Analysis of Neonatal T Cell and Antigen Presenting Cell Functions

ABSTRACT: Neonates are more susceptible to infection than adults and exhibit more intense or prolonged clinical symptoms. The extent to which deficiencies in T cell or antigen presenting cell (APC) function underlie hyporesponsiveness is incompletely understood. Here, immune function of cord blood mononuclear cells (CBMC) from healthy, full-term neonates was compared with adult PBMC. As widely reported, polyclonally-stimulated T cell proliferation was found to be equivalent, while IFNγ responses were markedly lower amongst neonates. Reasoning that such stimuli may elicit responses qualitatively different from those that would be obtained following MHC-dependent, cognate T cell activation, alloantigen-specific responses were evaluated. Strikingly, neonates exhibited IFNγ, IL-4 and IL-10 production equal to adults in short term primary culture. Both the frequency (Fisher’s p < 0.0004) and intensity (<7.5 vs 36.5 pg/ml; Wilcoxon P = 0.005) of alloantigen stimulated IL-5 responses were elevated among neonates, a finding equally evident using irradiated adult or neonatal cells as stimulators. Finally, the relative capacity of neonatal APC as stimulators of cytokine synthesis was assessed by a novel approach using CBMC as both responders and stimulators in MLR. Irradiated neonatal cells consistently stimulated similar proliferative but substantially lower IFNγ responses than did adult APC, independent of responder origin. The data argue; (i) T cells are largely immunocompetent at birth, (ii) accessory cell function is not fully mature, and (iii) the widely observed hyporesponsiveness to pathogens may be primarily due to immaturity of APC function or costimulator molecule expression.     

Astrocytic Factors Deactivate Antigen Presenting Cells that Invade the Central Nervous System

We hypothesized that CNS tissue has the potential to deactivate invading monocytes/macrophages in order to maintain the immune privilege of the brain, and furthermore, that astrocytes are the cells that initiate monocyte/macrophage deactivation. To test this hypothesis, fluorescent prelabeled rat spleen macrophages with typical amoeboid morphology were transferred into organotypic hip-pocampal slice cultures (OHSCs), where they gradually developed a ramified morphology similar to the appearance of resting microglial cells. This morphological transformation also occurred if macrophages or monocytes were co-cultured with mixed glial cultures or with astrocytoma cells, and ramification was accompanied by reduced expression of adhesion molecules leukocyte function antigen (LFA)-1, intercellular adhesion molecule (ICAM)-1, and major histocompatibility complex (MHC)-class-II molecules. Moreover, treatment of macrophages with astrocyte culture supernatant effectively down-regulated the LPS-induced expression of adhesion- and MHC-class-II-molecules. Astrocyte supernatant-induced inhibition of adhesion and MHC-class-II-molecule expression was mimicked by transforming growth factor (TGF)-β1, furthermore, this inhibitory effect was diminished by simultaneous treatment with neutralizing anti-TGF-β-antibodies. In conclusion, our results suggest that astrocyte-derived, soluble factors that are present in the CNS microenvironment deactivate invading macrophages, thus contributing to the maintenance of CNS immune-privilege following impairment of blood-brain-barrier (BBB) integrity.     

Rare Brain Tumor in a Neonate

Neonatal brain tumor is rare and its outcome is generally poor. We reported a 17-day-old neonate presented as enlarged head girth. The pathological finding showed an embryonal tumor with multilayered rosettes.     

Human Intestinal M Cells Display the Sialyl Lewis A Antigen

The biochemical features that distinguish human M cells from other intestinal epithelial cell types are important for understanding microbial pathogenesis and for targeting vaccines to the mucosal immune system. We applied a large panel of carbohydrate-specific monoclonal antibodies and lectins to Peyer’s patch and cecum biopsy specimens from three normal individuals and a patient with inflammatory bowel disease. The results show that human M-cell glycosylation patterns are distinct from those of other species examined and that human M cells preferentially display the sialyl Lewis A antigen. This carbohydrate epitope is also present in a small subpopulation of enterocytes in the follicle-associated epithelium and in goblet cell mucins.     

细胞内抗原免疫金银染色技术的改进

为解决细胞内抗原应用免疫金银法染色时背景过重的问题,建立了甘氨酸二次阻断的处理方法,效果较好。     

Antigen Presenting Cells in Human Decidual Tissue: III. Role of Accessory Cells in the Activation of Suppressor Cells

ABSTRACT: Human decidual antigen presenting cells (DAPCs) exposed to fetal cells in vitro induce generation of suppressor T cells among a population of peripheral blood lymphocytes. Human lymphocyte antigen (HLA)-class II positive antigen presenting cells were isolated from early normal human decidual tissue and from peripheral blood (PAPCs) by adhering Ficoll-Pa-que separated cell suspensions to fibronectin. In contrast to PAPCs, DAPCs pulsed with fetal antigens induced a radio-sensitive, Leu 1,2-positive T suppressor cell population. A nylon wool adherent B cell population is required during the in vitro induction of the suppressor cells. These suppressor cells impair primary mitogen and mixed lymphocyte culture (MLC) responses, generation of anti-trinitrophe-nyl (TNP) cytotoxic T lymphocytes, and antibody response of autologous and allogeneic lymphocytes. Only intact viable embryonic cells can effectively confer upon DAPCs the ability to induce T suppressor cells. The T suppressor cell induction by DAPCs primed with fetal antigens is restricted by the major histocompatibility complex. Our results show that the HLA-DR molecules are the most prominent restriction elements.     

Effect of UVB on Alloactivating and Antigen Presenting Capacity of Human Epidermal Langerhans Cells

Human epidermal cell suspensions (EC) were obtained by the suction blister technique and enzyme digestion. EC were irradiated in microtitre plates with doses up to 510 mJ/cm2 (2.6 minimal erythemal dose (MED] by means of fluorescent light bulbs emitting a 280-320 nm continuous spectrum with a peak at 310 nm. Purified allogeneic T cells were added to the EC immediately or 24 h after radiation. Irradiated EC were pulsed with purified protein derivative (PPD) for 90 min immediately or 24 h after radiation and then cocultured with purified autologous T cells. PPD-pulsed EC were also irradiated before being cocultured with autologous T cells. Pretreatment of EC suspensions with anti-DR antiserum plus complement abolished both the alloactivating and the antigen-presenting capacity, indicating that the DR-positive Langerhans cells are mainly responsible for these functions. There were no differences in the number of DR-positive cells in EC before or immediately after radiation. A statistically significant and UV-dose-dependent reduction of the alloactivating ability of EC was found both when allogeneic T cells were added immediately and when they were added 24 h after radiation. Likewise, a significant and dose-dependent reduction of the PPD-specific T-cell response was obtained in cultures when using irradiated EC that were PPD-pulsed immediately or 24 h after radiation. EC that were first PPD-pulsed and then irradiated induced a significantly increased T-cell response after low UV doses (1 or 2 MED), whereas higher doses induced a significant reduction of the T-cell responses.     

B Cells Carrying Surrogate Receptors in their Membranes Process and Present Antigen to Specific Murine T Cells

A palmitate-conjugate derivative of ovalbumin which can be inserted into the membrane of B cells has been prepared. The ability of these cells to act as antigen-presenting cells for specific T lymphocytes obtained from immunized mice was tested. It was found that the conjugates were more efficiently processed and presented than the naive form of the antigen. Palmitate-conjugated antibodies specific to ovalbumin were also inserted into the cell membrane of normal B lymphocytes. These cells were pulsed with the antigen and tested as antigen-presenting cells for T cells obtained from immunized mice. The antibody-decorated B cells presented ovalbumin more efficiently than non-decorated controls. Whether antibody-decorated, antigen-pulsed B cells could prime T cells in viro was investigated. Some priming activity was found.     

树突状细胞在人皮肤黑色素瘤组织中抗原提呈效应的形态学观察

目的探讨人皮肤黑色素瘤组织中肿瘤浸润树突状细胞（TIDC）的抗肿瘤效应。方法采用光镜、透射电镜和免疫组化方法观察19例手术切除的人皮肤黑色素瘤中TIDC和肿瘤浸润淋巴细胞（TIL）抗肿瘤效应的形态学表现。结果早期人皮肤黑色素瘤组织中的类高内皮微静脉和淋巴管内、外均可见大量淋巴细胞和树突状细胞集聚和迁移;病变早期TIDC和TIL浸润比晚期明显（P〈0．01）。透射电镜下,TIDC大致有两种形态。一种TIDC体积大,表面有许多树枝状突起,核不规则,胞浆内有丰富的细胞器;另一种TIDC突起较少,细胞器也较少。TIDC与肿瘤细胞、TIDC与TIL、TIL与TIL、TIL与肿瘤细胞之间存在多种形式的膜接触。与TIL接触的肿瘤细胞呈凋亡状态。晚期病变组织中TIDC与TIL数量明显减少,于癌巢内常见凋亡的TIDC与TIL。结论人皮肤黑色素瘤组织中存在不同形态的TIDC与TIL,并通过类高内皮微静脉和淋巴管迁移;TIDC、TIL、癌细胞彼此密切作用,在肿瘤局部即可发生抗肿瘤免疫应答反应,反应程度与肿瘤进展呈负相关。     

Identity of HML-1 Antigen on Intestinal Intraepithelial T Cells and of B-ly7 Antigen on Hairy Cell Leukaemia

Immunoprecipitation of radioiodinated hairy cell leukaemia (HCL) cell lysates with monoclonal antibody (MoAb) HML-1, originally reported to recognize intraepithelial T cells, and with MoAb B-ly7, originally reported to react with HCL, led to identical biochemical characteristics. In SDS-PAGE under reducing conditions, a major band of 143 kDa, a broad band ranging from 112 to 122 kDa, and two additional faint bands of 175 and 100 kDa could be determined. Deglycosylation of N-linked sugar moieties by treatment of immunoprecipitates with endoglycosidases indicated that the two main protein cores of the antigen are predominantly if not exclusively glycosylated by complex and hybrid types of oligosaccharide chains. Competitive binding inhibition demonstrated that both MoAb are directed against different epitopes. Immunohistochemically, the staining patterns obtained with both MoAb in normal tissues, in T- and B-cell lymphomas, and in HCL were identical except for a single case of HCL which was HML-1-/B-ly-7+. We conclude that MoAb HML-1 and B-ly7 recognize the same antigen.     

新生儿心肺功能监护仪的设计与新生儿生理参数的确定

本文介绍了新生儿心肺功能监护仪的软硬件设计,该仪器具有体积小,功能全面,适用性广,操作简单等特点,能可靠地实现对新生儿的监护,用该仪器对新生儿的血氧饱各度和心率这两个最重要的生理参数的测定获取了中国新生儿呼吸系统的数据,对数据的统计分析表明,血氧饱和度和心率这两个最重要热处理到达数的测定获取了中国新生儿呼吸系统的数据,对数据的统计分析表明,血氧饱和度和心率都属于正态分布,并依此给出了中国新生婴儿的这两个参数的分布范围。     

新生儿消化道穿孔X线表现及病因与预后研究

目的　深入了解新生儿消化道穿孔X线表现 ,并对发病部位与发病原因及预后评估进行探讨 .方法　对照分析了 2 4例临床手术资料与X线征象 .结果　各种位置X线检查发现气腹 2 3例 ,大量气腹 7例 ,中量气腹 11例 ,少量气腹 5例 .气腹的X线征象除膈下游离气体外 ,在卧位或水平侧位片还可见足球征 13例 ,镰状韧带征 12例 ,铅笔征或Rigler氏征 10例 ,“黑三角征”3例 .气腹以外的其它征象是 :胃泡影消失 6例 ,肠管少气 11例 ,肠管充气增多12例 ,肠管无气 1例 ,肠间隙增宽 12例 ,肠壁积气 5例 ,腹腔液体增多 15例 ,外围肠管可见气粪混合征 3例 .肠穿孔原因 :胃壁先天性肌层缺损 5例 ,各种先天性小肠畸形 6例 ,结肠和直肠畸形 4例 ,坏死性小肠结肠炎 7例 ,胎粪性腹膜炎 1例 .结论　X线检查仍然是发现新生儿消化道穿孔的重要首选方法 ,对穿孔的原因和预后评估有一定帮助     

Administration of Silica Sensitizes Lipopolysaccharide Responsiveness of Murine Macrophages but Inhibits T and B Cell Priming by Inhibition of Antigen Presenting Function

Macrophages play a key role in natural host defense against infection by a variety of pathogens. In addition, macrophages initiate the development of acquired immunity via antigen processing and presentation. The role of macrophages in resistance to pathogens, the development of autoimmune diseases and the induction of acquired immunity has been studied by treatment of rodents with reagents which are cytotoxic. We have studied the effects of one such reagent, silica, on the function of spleen macrophages and peritoneal exudate cells (PEC). Intraperitoneal administration of silica caused the accumulation of spleen macrophages and neutrophils, reduction in the number of B cells and had a modest effect on T cell abundance. The percentage of CD11b⁺ PEC was not affected by silica treatment but total PEC recovery was diminished 5-8 fold. Silica treatment did not cause release of TNF-alpha or IL-1-beta but, when stimulated with lipopolysaccharide (LPS) in vitro after silica treatment, PEC or spleen macrophages produced elevated levels of both cytokines compared to controls. In contrast, release of IL-12 from non-LPS treated PEC was stimulated 4-5 fold by silica treatment. In addition, sensitivity to LPS toxicity in vivo was significantly enhanced by silica. The ability of macrophages to present antigen to a T cell clone in vitro was found to be dramatically inhibited by silica treatment, as was the ability to prime antigen-specific T cells and B cells by antigen injection. Collectively these data demonstrate that silica treatment enhances macrophage sensitivity to LPS exposure but inhibits antigen processing and presentation.     

Second Messenger-Induced Modulation of Thy-1 Antigen Expression: An Elisa Study Using Murine Thymic and Neuroblastoma Cells

Freshly isolated cells of murine thymuses and in vitro cultured murine neuroblastoma cells were seeded into microplates, treated with either phorbol myristate acetate (PMA) or dibutyryl-cyclic adenosine monophosphate (DBcAMP), and then processed for enzyme imunoassay to analyze with G4 monoclonal antibody the expression of Thy-1.2 antigen epitope. Pretreatment of thymic cells with PMA resulted in little, if any, decrease of Thy-1 expression, while treatment of these cells with DBcAMP caused a significant down-modulation of the epitope. DBcAMP did not affect binding of another murine IgG antibody to the thymic cells. Modulation of the epitope on thymic cells caused by DBcAMP was dose-dependent with maximal effect seeen at the drug concentration of 10^-4M. However, at various doses of DBcAMP (10^-6 to 10^-4 M) we were unable to detect any significant shift of Thy-1 expression on neuroblastoma cells. Though mechanisms of the above phenomena need further elucidation, we conclude that cellular ELISA may provide a useful alternative to more commonly used cytofluorimetric studies for the analysis of immune cell-surface antigen expression and its pharmacological and physiological modulation.     

Priming to Mycobacterial Antigen In Vivo Using Antigen-Pulsed Antigen Presenting Cells Generated In Vitro is Influenced by the Dose and Presence of IL-4 in APC Cultures

Antigen presenting cells (APC) similar to immature dendritic cells can be generated in vitro from bone marrow precursors. The authors have compared the yield, the phenotype and the function of murine bone marrow cells cultured for 7 or 11 days in either granulocyte macrophage colony stimulating factor alone (GM BMAPC) or in combination with interleukin-4 (GM/IL-4 BMAPC). The results showed that GM/IL-4 BMAPC expressed the highest levels of MHC Class 2 molecules, CD86 /B7-2 and CD80/B7-1 co-stimulatory molecules and the lowest levels of F4/80 macrophage marker. However, when these APC were pulsed with BCG culture filtrate antigen or PPD they were not correspondingly more effective at stimulating activated T lymphocytes in vitro or priming naive T lymphocytes in vivo . Also, in contrast to GM BMAPC, high backgrounds recorded following injections of GM/IL-4 BMAPC without antigen were not consistently reduced by lowering the dose and irradiating the cells prior to administration. The authors conclude that the degree of maturity of BMAPC varies with culture conditions and that this may be an important consideration where BMAPC are to be used in vivo in immunotherapeutic regimens.     

A Trypanosoma cruzi Alkaline Antigen Induces Polyclonal B-Cell Activation of Normal Murine Spleen Cells by T-Cell-Independent, BCR-Directed Stimulation

We have previously reported that a cytosolic alkaline fraction (FI) obtained from epimastigotes of Trypanosoma cruzi promotes the activation, proliferation and differentiation of normal murine B cells into antibody-secreting plasmocytes. Neither the mechanism nor the cells involved in the FI-induced polyclonal B-cell activation were established. In this work we report that accessory cells are required for FI-induced polyclonal B-cell activation as no proliferative responses were obtained following treatment of normal spleen mononuclear cells (NSMC) with L-leucine methyl ester. Furthermore, FI did not induce the expression of CD25 on T cells and it promoted the proliferation of a T-cell-depleted population, indicating that it acts in a T-independent manner. We observed that NSMC were stimulated in vitro by FI-released cytokines, such as interleukin (IL)-4, IL-6 and IL-10, which are involved in B-cell proliferation and differentiation. Interestingly, while significant amounts of interferon-gamma (IFN-gamma) were found in culture supernatants we did not observe detectable levels of IL-2. Additionally, we found that B-cell receptor (BCR) and major histocompatibility complex (MHC) class II antigens were involved in the proliferative response induced by FI because antibodies directed against cell-surface immunoglobulin M (IgM), CD45 and MHC class II molecules inhibited the FI-induced B-cell proliferation. CD40 ligand (CD40L) did not participate in such a phenomenon.