Intestinal antigen-presenting cells in mucosal immune homeostasis:Crosstalk between dendritic cells,macrophages and B-cells

The intestinal immune system maintains a delicate balance between immunogenicity against invading pathogens and tolerance of the commensal microbiota.Inflammatory bowel disease(IBD)involves a breakdown in tolerance towards the microbiota.Dendritic cells(DC),macrophages(MΦ)and B-cells are known as professional antigen-presenting cells(APC)due to their specialization in presenting processed antigen to T-cells,and in turn shaping types of T-cell responses generated.Intestinal DC are migratory cells,unique in their ability to generate primary T-cell responses in mesenteric lymph nodes or Peyer’s patches,whilst MΦand B-cells contribute to polarization and differentiation of secondary T-cell responses in the gut lamina propria.The antigen-sampling function of gut DC and MΦenables them to sample bacterial antigens from the gut lumen to determine types of T-cell responses generated.The primary function of intestinal B-cells involves their secretion of large amounts of immunoglobulin A,which in turn contributes to epithelial barrier function and limits immune responses towards to microbiota.Here,we review the role of all three types of APC in intestinal immunity,both in the steady state and in inflammation,and how these cells interact with one another,as well as with the intestinal microenvironment,to shape mucosal immune responses.We describe mechanisms of maintaining intestinal immune tolerance in the steady state but also inappropriate responses of APC to components of the gut microbiota that contribute to pathology in IBD.

Impact of PRRSV on activation and viability of antigen presenting cells

Porcine reproductive and respiratory syndrome(PRRS) is one of the most important diseases of swine industry. The causal agent, PRRS-virus(PRRSV), is able to evade the host immune response and survive in the organism causing transient infections. Despite all scientific efforts, there are still some gaps in the knowledge of the pathogenesis of this disease. Antigen presenting cells(APCs), as initiators of the immune response, are located in the first line of defense against microorganisms, and are responsible for antigen recognition, processing and presentation. Dendritic cells(DCs) are the main type of APC involved in antigen presentation and they are susceptible to PRRSV infection. Thus, PRRSV replication in DCs may trigger off different mechanisms to impair the onset of a host effective immune response against the virus. On the one side, PRRSV may impair the basic functions of DCs by regulating the expression of major histocompatibility complex class Ⅱ and CD80/86. Other strategy followed by the virus is the induction of cell death of APCs by apoptosis, necrosis or both of them. The impairment and/or cell death ofAPCs could lead to a failure in the onset of an efficient immune response, as long as cells could not properly activate T cells. Future aspects to take into account are also discussed in this review.

Probiotic metabolites from Bacillus coagulans GanedenBC30^(TM) support maturation of antigen-presenting cells in vitro

AIM:To study the effects of probiotic metabolites on maturation stage of antigen-presenting immune cells.METHODS:Ganeden Bacillus coagulans 30(GBC30) bacterial cultures in log phase were used to isolate the secreted metabolite(MET) fraction.A second fraction was made to generate a crude cell-wall-enriched fraction,by centrifugation and lysis,followed by washing.A preparation of MET was subjected to size exclusion centrifugation,generating three fractions:< 3 kDa,3-30 kDa,and 30-200 kDa and activities were tested in comparison to crude MET and cell wall in primary cultures of human peripheral blood mononuclear cell(PBMC) as a source of antigen-presenting mononuclear phagocytes.The maturation status of mononuclear phagocytes was evaluated by staining with monoclonal antibodies towards CD14,CD16,CD80 and CD86 and analyzed by flow cytometry.RESULTS:Treatment of PBMC with MET supported maturation of mononuclear phagocytes toward both macrophage and dendritic cell phenotypes.The biological activity unique to the metabolites included a reduction of CD14+ CD16+ pro-inflammatory cells,and this property was associated with the high molecular weight metabolite fraction.Changes were also seen for the dendritic cell maturation markers CD80 and CD86.On CD14dim cells,an increase in both CD80 and CD86 expression was seen,in contrast to a selective increase in CD86 expression on CD14bright cells.The co-expression of CD80 and CD86 indicates effective antigen presentation to T cells and support of T helper cell differentiation.The selective expression of CD86 in the absence of CD80 points to a role in generating T regulatory cells.CONCLUSION:The data show that a primary mechanism of action of GBC30 metabolites involves support of more mature phenotypes of antigen-presenting cells,important for immunological decision-making.

Cinnamon extract suppresses experimental colitis through modulation of antigen-presenting cells

AIM:To investigate the anti-inflammatory effects of cinnamon extract and elucidate its mechanisms for targeting the function of antigen presenting cells.METHODS:Cinnamon extract was used to treat murine macrophage cell line(Raw 264.7),mouse primary antigen-presenting cells(APCs,MHCII+) and CD11c+dendritic cells to analyze the effects of cinnamon extract on APC function.The mechanisms of action of cinnamon extract on APCs were investigated by analyzing cytokine production,and expression of MHC antigens and co-stimulatory molecules by quantitative real-time PCR and flow cytometry.In addition,the effect of cinnamon extract on antigen presentation capacity and APC-dependent T-cell differentiation were analyzed by [H3]-thymidine incorporation and cytokine analysis,respectively.To confirm the anti-inflammatory effects of cinnamon extract in vivo,cinnamon or PBS was orally administered to mice for 20 d followed by induction of experimental colitis with 2,4,6 trinitrobenzenesulfonic acid.The protective effects of cinnamon extract against experimental colitis were measured by checking clinical symptoms,histological analysis and cytokine expression prof iles in inflamed tissue.RESULTS:Treatment with cinnamon extract inhibited maturation of MHCII+ APCs or CD11c+ dendritic cells(DCs) by suppressing expression of co-stimulatory molecules(B7.1,B7.2,ICOS-L),MHCII and cyclooxygenase(COX)-2.Cinnamon extract induced regulatory DCs(rDCs) that produce low levels of pro-inflammatory cytokines [interleukin(IL)-1β,IL-6,IL-12,interferon(IFN)-γ and tumor necrosis factor(TNF)-α] while expressing high levels of immunoregulatory cytokines(IL-10 and transforming growth factor-β).In addition,rDCs generated by cinnamon extract inhibited APC-dependent T-cell proliferation,and converted CD4+ T cells into IL-10high CD4+ T cells.Furthermore,oral administration of cinnamon extract inhibited development and progression of intestinal colitis by inhibiting expression of COX-2 and pro-inflammatory cytokines(IL-1β,IFN-γ and TNF-α),while enhancing IL-10 levels.CONCLUSION:Our study suggests the potential of cinnamon extract as an anti-inflammatory agent by targeting the generation of regulatory APCs and IL-10+ regulatory T cells.

Interaction between antigen presenting cells and autoreactive T cells derived from BXSB mice with murine lupus

全身的豺狼座 erythematosus (SLE ) 是包含多重系统和机关的典型自体免疫病。宽大的证据建议反应 T 房间玩的那辆汽车在这自体免疫的混乱的发展的一个枢轴的角色。这研究被承担调查在介绍房间(APC ) 和反应 T 房间(ATL1 ) 克隆从豺狼座容易的 BXSB 老鼠获得了的一辆汽车的抗原之间的相互作用的机制。ATL1 房间，在 gamma 光线照耀前后的任何一个，能激活天真的 B 房间，由 B 细胞增殖试金决定了。巨噬细胞 fromBXSB 老鼠能刺激在一个应答者 / 激发器(R/S ) 放松 ATL1 房间的增长 1/2.5 的比率。树枝状的房间(DC ) 是为 aper 房间基础上的 ATL1 房间的更强大的激发器。刺激巨噬细胞的能力的 T 房间和 B 房间，然而并非 DC，对 gamma 光线敏感照耀。对老鼠 MHC-II 和 CD4 的 Monoclonal 能堵住 ATL1 增长的调停 DC 的刺激，显示在 ATL1 andAPCs 之间的血缘的识别。我们的数据建议包含巨噬细胞， B 房间和 autoreactiveT 房间的积极反馈环可以在保留导致自体免疫病的自体免疫的回答的动量起一个枢轴的作用。

Cilostazol inhibits plasmacytoid dendritic cell activation and antigen presentation

BackgroundCilostazol，为治疗冠的心疾病的反血小板药，被报导了调制有免疫力的房间功能。Plasmacytoid 树枝状的房间(pDCs ) 被发现了主要通过干扰素 &#x003b1 参予动脉粥样硬化的前进；(IFN-&#x003b1；) 生产。cilostazol 是否影响 pDCs 激活，仍然不是清楚的。在这研究，我们试图在房间由流动 cytometry 排序的 Ficoll centrifugation 和 pDCs 孤立的这 study.MethodsPeripheral 血 mononuclear 在 vitro 在房间激活和 pDCs 的抗原表示上调查 cilostazol 的效果在这研究被使用。在有为 2 h 的 cilostazol 的 pretreated 以后，房间与 CpG 被刺激 -- 为 6 h 或 20 h 的 A， R848 或病毒，或为 48 h 与 CpG-B 刺激了然后与 na&#x000ef co 有教养；为五天的 ve T 房间。在上层清液和细胞内部的 cytokines 的 Cytokines 被 ELISA 分析或流动 cytometry respectively.ResultsOur 数据显示 cilostazol 能禁止 IFN-&#x003b1；并且肿瘤坏死因素 &#x003b1；(TNF-&#x003b1；) 从以一种剂量依赖者方式的 pDCs 的生产。另外， priming na&#x000ef 的能力； pDCs 的 ve T 房间被 cilostazol 也损害。自从 pDCs 的生存能力没在 cilostazol treatment.ConclusionCilostazol 之上变化，禁止的效果不由于房间杀死在 vitro 禁止 pDCs 房间激活和抗原表示，它可以解释 cilostazol 怎么免于动脉粥样硬化。

HBsAg loading on dendritic cells in patients with chronic hepatitis B: expressions of phenotypic molecules

BACKGROUND: The antigen reducing ability of dentritic cells (DCs), a kind of antigen presenting cells (APCs) initiating immune response, is associated with the specific immune tolerance of chronic hepatitis B(CHB) patients. However, the dysfunction of DCs can be possibly reversed by the stimulation of antigen peptides. In this study, DCs were cultured from peripheral blood monocytes (PBMCs) in patients with CHB in vitro, and the expression of phenotypic molecules on DCs loaded by different concentrations of HBsAg was observed. METHODS: Forty patients with CHB were divided randomly into 4 groups(10 patients in each group). PBMCs were isolated, and DCs were cultured after addition of granulocyte/macrophage colony-stimulating factor (GMCSF) and interleukin 4(IL-4). On the 9th day, DCs of the experimental groups were loaded at HBsAg concentrations of 2.5mg/L, 5mg/L and 10mg/L for 24 hours, whereas those of the control group were not loaded. An electron microscope was used to analyze the morphological changes of the DCs. The expression of phenotypic molecules on DCs in different groups was detected with flow cytometry. RESULTS: A combination of GM-CSF and IL-4 produced DCs from PBMCs in patients with CHB after being cultured for 9 days, whose morphological changes were tested by an electron microscope. The expression of phenotypic molecules on DCs in the control group was as low as CD83 (8.02±3.99)%, CD80(8.77±2.06)%, and MHC-DR (14.05±2.66)%. Loaded by different concentrations of HBsAg, the up-regulation of phenotypic molecules on DCs was found, with CD83(18.35±2.93)%, CD80(42.63±7.15)% and MHC-DR(47.49±6.59)% in 2.5mg/L HBsAg loading group, CD83(17.88±3.12)%, CD80(45.24± 10.93)% and MHC-DR(47.07±8.52)% in 5mg/L HBsAg loading group and CD83(16.74±2.86)%, CD80(44.59±6.99)% and MHC-DR(48.59±7.42)% in 10mg/L HBsAg loading group, respectively. Compared with the control group, the phenotypic molecules in the experimental groups were all different significantly (P<0.01), but among them, there were no differences (P>0.05). CONCLUSIONS: DCs cultured from PBMCs in the patients with CHB under the conditions of GM-CSF and IL-4 present on the typical dendritic morphology but are immature for expressing low phenotypic molecules. Loaded by different concentrations of HBsAg, the immature DCs can differentiate to mature DCs for expressing increasing phenotypic molecules.

Targeting epidermal Langerhans cells by epidermal powder immunization

Immune reactions to foreign or self-antigens lead to protective immunity and, sometimes, immune disorders such as allergies and autoimmune diseases. Antigen presenting cells (APC) including epidermal Langerhans cells (LCs) play an important role in the course and outcome of the immune reactions. Epidermal powder immunization (EPI) is a technology that offers a tool to manipulate the LCs and the potential to harness the immune reactions towards prevention and treatment of infectious diseases and immune disorders.

Inducible expression of endomorphins in murine dendritic cells

Bone marrow precursor cells were extracted from C57BL/6J mice aged 7-8 weeks, and dendritic cells were purified using anti-CD1 lc （a specific marker for dendritic cells） antibody-coated magnetic beads. Immunofluorescence staining revealed that the expression levels of endomorphin-1 and endomorphin-2 were upregulated in dendritic cells activated by lipopolysaccharide. An enzyme Jmmunoassay showed that lipopolysaccharide and other Toll-like receptor ligands promoted the secretion of endomorphin-1 and endomorphin-2 from activated dendritic cells. [3H]-thymidine incorporation demonstrated that endomorphin-1 and endomorphin-2 both inhibited the proliferation of T lymphocyte induced by activated dendritic cells. Furthermore, this immunosuppressive effect was blocked by CTOP, a specific antagonist of IJ-opioid receptors. Our experimental findings indicate that activated dendritic cells can induce the expression and secretion of endomorphins, and that endomorphins suppress T lymphocyte proliferation through activation of iJ-opioid receptors.

Role of Dendritic Cells in Myocarditis Induced by Coxsackie B_3 Virus in Mouse

Background and Objectives Autoimmune reaction may play an important role in the pathogenesis and progress in virus myocarditis. Dendritic cells are the initiators of immune reaction to foreign antigens and are considered to be key players in the induction and maintenance of autoimmune reactions. This study was undertaken to investigate the role of DC in mice with virus myocarditis. Methods and Results Fifty Balb/c mice were injected Coxsackie B3 virus to induce myocarditis and ten mice were injected culture liquid as control group. The hearts of virus - infected mice were harvested on day 3, 7, 14, 28 after the injection. All the hearts were sliced to do HE staining, MHC Ⅱ antigen and S - 100 protein immunohistochemical staining. The inflammation response and expression of MHC Ⅱ antigen and S - 100 protein positive stained cells were observed. The MHC Ⅱ antigen positive score were 1.42±0.95, 2.24 ±1. 00, 3. 23± 1. 16, 2. 58 ± 1. 05 respectively in group 3d, 7 d, 14 d, 28 d, which were significant different from control group(0. 50 ±0.75, P <0. 05). The S-100 positive staining cells in control group was 3. 2±1. 0. And the numbers were 6. 7 ± 1. 4 , 16. 4 ± 2. 5 , 21. 2±3. 3 , 13. 4 ± 2. 3 respectively in group 3 d, 7 d, 14 d, 28 d, and there were significant differences compared with the control group ( P < 0. 01) . Conclusions Immune reaction was involved in the pathogenesis in Coxsackie B3 virus - induced myocarditis in mouse, and dendritic cell might play an important role in the immune reaction.

Co-Inhibitors of Second Signal of Lymphocyte Response in Human Renal Transplants: PD-L2, GITR, and ILT-2/3/5 Positive Cells from Aspiration Biopsies Associate with Acute Rejection-Freedom

Following organ transplantation, the outcome of the encounter between an APC and a T lymphocyte is strongly dependent on the presence of costimulatory and co-inhibitory molecules, the former associated with allograft rejection and the latter with allograft acceptance. We evaluated the expression of PD-L2, GITR, ILT-2/3/5, and ILT-4 on graft-infiltrating cells procured by Fnab from human KTx under different immunosuppressive regimens. Methods: Fnab biopsies were performed on days 7 or 14 - 30 in stable KTx and on the day of acute rejection diagnosis. Cytopreparations were studied by the enzymatic avidin biotin complex staining. Results: Acute rejection group showed a significant down-regulated expression of PD-L2, GITR, and ILT-2/3/5 as compared to stable group, while for ILT-4 we did not find significant difference. Anti-IL2αR and rapamicyn treatment trend to down-regulate ILT-4 expression, although meaningless. A significantly positive correlation was observed between PD-L2 and GITR expression in Fnab. The PPV for acute rejection diagnosis for both PD-L2 and GITR was clearly above 0.8. Conclusions: Our findings point to an early entrance of cells expressing PD-L2, GITR and ILT-2/3/5 inside human KTx who are going to remain rejection-free. Both PD-L2 and GITR shared a high ability to rule-in and rule-out acute rejection.

Antigen-presenting effects of effector memory Vγ9Vδ2 T cells in rheumatoid arthritis

Rheumatoid arthritis is an autoimmune disease that primarily affects the limbs, but the pathogenic mechanism remains unclear. 78 T cells, a T-cell subpopulation, are characterized by multiple biological functions and associated with a variety of diseases. This study investigated the antigen-presenting effects of γδ2 cells and their relationship with rheumatoid arthritis development. We found that Vγ9Vδ2 T cells （the predominant subtype of γδ T cells in peripheral blood） were activated by isopentenyl pyrophosphate to continuously proliferate and differentiate into effector memory cells. The effector memory Vγ9Vδ2 T cells exhibited phenotypic characteristics of specific antigen-presenting cells, including high HLA-DR and CD80/86 expression. These Vγ9Vδ2 T cells could present soluble antigens and synthetic peptides to CD4＋ T cells. Vγ9Vδ2 T cells with different phenotypes showed different cytokine secretion patterns. Effector memoryVγ9Vδ2 T cells simultaneously secreted not only interferon （IFN）-γbut also IL-17. The peripheral blood and joint synovial fluid from RA patients contained numerous heterogeneous γδ T cells that were predominantly effector memory Vγ9Vδ2 T cells with the ability to secrete inflammatory factors. We also found that γδ T cells had a similar antigen-presenting capability to B cells. These results suggest that during the development of rheumatoid arthritis, 78 T cells can aggravate immune dysfunction and produce abnormal immune damage by secreting cytokines and inducing inflammatory cells to participate in synergistic inflammatory responses. Furthermore, γδ T cells can behave similarly to B cells to present viral peptides and autoantigen peptides to CD4＋ T cells, thus sustaining CD4＋ T-cell activation.

Establishment and Characterization of a Cell Based Artificial Antigen-Presenting Cell for Expansion and Activation of CD8^+ T Cells Ex Vivo

Artificial antigen-presenting cells are expected to stimulate the expansion and acquisition of optimal therapeutic features of T cells before infusion. Here CD32 that binds to a crystallizable fragment of IgG monoclonal antibody was genetically expressed on human K562 leukemia cells to provide a ligand for T-cell receptor. CD86 and 4-1BBL, which are ligands of co-stimulating receptors of CD28 and 4-1BB, respectively, were also expressed on K562 cells. Then we accomplished the artificial antigen-presenting cells by coupling K32/CD86/4-1BBL cell with OKT3 monoclonal antibody against CD3, named K32/CD86/4-1BBL/OKT3 cells. These artificial modified cells had the abilities of inducing CD8^＋ T cell activation, promoting CD8^＋ T cell proliferation, division, and long-term growth, inhibiting CD8^＋ T cell apoptosis, and enhancing CD8^＋ T cell secretion of IFN-T and perforin. Furthermore, antigen-specific cytotoxic T lymphocytes could be retained in the culture stimulated with K32/CD86/4-1BBL/OKT3 cells at least within 28 days. This approach was robust, simple, reproducible and economical for expansion and activation of CD8^＋ T cells and may have important therapeutic implications for adoptive immunotherapy. Cellular ＆ Molecular Immunology.

T细胞免疫反应载体疫苗在人类疾病预防和治疗中的应用

人类疾病,特别是传染病和癌症,对公共卫生安全和全球经济构成前所未有的挑战。预防和治疗性疫苗的开发是应对人类疾病的优先对策。本文综述了疫苗载体的免疫学原理、T细胞载体疫苗设计策略及疫苗研究进展,为新型疫苗的设计提供新的思路。T细胞可以在机体发生感染后分化成不同的效应T细胞群,它们可以起到清除病原体的作用,关于效应T细胞功能和机制的研究对于设计能够引发基于T细胞免疫的疫苗至关重要。目前很多病毒(例如HIV、HCMV感染)和肿瘤疫苗的研发都侧重于T细胞类疫苗,在所有疫苗种类中,激活T细胞免疫反应的载体疫苗具有显著优势。许多来源的载体,包括病毒载体、细菌载体和核酸载体,它们在抗原提呈能力、免疫原性和保护效力方面都有良好的表现。此外,还总结了T细胞载体疫苗设计的策略,包括确定适当的抗原提呈途径和载体递送途径、确保生物安全性、如何选择合适的疫苗的载体、各种载体疫苗的优缺点等,尤其是mRNA疫苗在应对新冠疫情中发挥了重要的作用。疫苗载体的技术进步将会加速新型疫苗的研发,并且能促进人们对突发公共卫生事件的应对。

APC在结核杆菌低分子多肽抗原体外激活人外周血γ^(δ+)T细胞中的作用

目的探讨抗原递呈细胞APC在结核杆菌Mtb低分子多肽抗原体外激活人外周血γδ+T细胞中的作用。方法用平皿粘附和尼龙毛柱纯化法,从PBMC中分离单核细胞、B淋巴细胞然后分别与纯化的T细胞共育在Mtb抗原的刺激下,观察γδ+T细胞的增殖效应。结果Mtb低分子多肽抗原在激活γδ+T细胞时,需要单核细胞、B细胞等APC的存在但APC并不起摄取、加工、递呈抗原的作用。结论γδ+T细胞具有与γδ+T细胞不同的独特抗原识别方式。

B细胞在非感染性葡萄膜炎中的研究进展

非感染性葡萄膜炎是一种严重威胁视力,治疗棘手的自身免疫性眼病。目前主流观点认为非感染性葡萄膜炎的发病机制是主要由CD4+T细胞介导的免疫失衡。但近年来许多证据表明B细胞也发挥关键作用,通过产生抗体、抗原提呈、分泌细胞因子、形成异位淋巴结构等多种方式参与到实验性自身免疫性葡萄膜炎模型及人类葡萄膜炎中。针对B细胞的治疗已广泛应用于多种自身免疫性疾病。利妥昔单抗,一种B细胞抑制剂,在对传统皮质类固醇和免疫抑制剂治疗无效的难治性非感染性葡萄膜炎中发挥不错疗效。本文总结了B细胞在非感染性葡萄膜炎中的作用及细胞疗法,旨在为更深入的机制研究提供理论基础,并为开发精准有效的防治策略开辟新视角。

抗原提呈细胞亚群预测肝癌患者的免疫治疗疗效研究

背景原发性肝细胞癌(hepatocellular carcinoma,HCC)患者中免疫治疗应用广泛,但需寻找有效的疗效预测标志物,以此提供个体化和精准化的治疗。目的探讨抗原提呈细胞(antigen presenting cell,APC)亚群与HCC患者免疫治疗的疗效关系。方法前瞻性纳入2022年5月—2023年9月在解放军总医院第五医学中心初次接受免疫治疗的中晚期HCC患者,通过流式细胞仪检测免疫治疗前的B细胞/淋巴细胞(B/LYM)、巨噬细胞/所有核细胞(MA/TNC)和树突细胞/所有核细胞(DC/TNC)的比值。根据均值将患者分为高水平组和低水平组,并比较两组间无进展生存期(progression free survival,PFS),并通过Cox分析影响PFS的因素。最后利用ROC曲线预测疾病控制的效能。结果共纳入84例患者,中位年龄为57岁;男性58例,女性26例。APC亚群基线数据:B/LYM均值为16.54%±6.27%,MA/TNC均值为9.14%±2.87%,DC/TNC均值为0.051%±0.021%。Kaplan-Meier生存分析和Cox回归分析显示B/LYM高值组的mPFS显著高于低值组(5.90个月vs 5.50个月,P=0.019;HR=0.588,95%CI:0.358~0.966),MA/TNC低值组的mPFS显著高于高值组(7.20个月vs 5.40个月,P=0.034;HR=0.617,95%CI:0.374~1.019),DC/TNC高值组的mPFS显著高于低值组(6.30个月vs 5.50个月,P=0.026;HR=0.615,95%CI:0.378~0.955)。且高水平的MA/TNC是疾病进展的独立危险因素,高水平的DC/TNC、B/LYM是疾病进展的保护因素。基线B/LYM、MA/TNC、DC/TNC对HCC患者接受2周期治疗后的疾病控制情况而言,具有较好的预测效能,且联合应用时效能进一步提高,AUC分别为0.685、0.723、0.745、0.865。结论高DC/TNC、B/LYM水平和低MA/TNC水平的HCC患者,可能更容易从免疫治疗中获益。

真菌毒素对树突状细胞免疫应答的影响

真菌毒素是病原真菌产生的次级代谢产物,常污染多种农作物,通过食物链对人畜健康造成严重危害。真菌毒素具有多种毒性作用,包括神经毒性、肝毒性、免疫毒性、致畸性和致癌性等,但其免疫毒性机制尚不完全清楚。树突状细胞(DCs)作为功能最强大的抗原提呈细胞,在启动先天免疫和获得性免疫应答中发挥重要作用。现有研究发现真菌毒素能够影响DCs的内吞作用、刺激T细胞活化的能力以及细胞因子和趋化因子的分泌,本文旨在综述真菌毒素对DCs免疫应答的影响,为后续研究阐明真菌毒素的免疫毒性机制提供参考。

粘附细胞作为APC提高MS淋巴细胞对髓鞘抗原增殖反应的探索

目的 比较粘附细胞作为APC能否较一般方法提高T细胞对神经髓鞘类抗原的增殖反应性和显示出MS对神经髓鞘类抗原的特异自身免疫反应特征。方法 选HLA DR15亚型MS和正常人外周血单个核细胞 ,体外培养。分别用一般T淋巴细胞增殖试验和富集粘附细胞法检测对人神经髓鞘、蛋白脂蛋白 (PLP)和碱性髓鞘蛋白(MBP)淋巴细胞增殖反应性。结果 富集粘附细胞法使MS组和对照组T淋巴细胞对神经髓鞘、PLP和MBP的增殖较标准法提高 (P <0 .0 5 ) ;使MS组以MBP和PLP的增殖反应较对照组的差别具有显著性的意义 ;而对TT无明显提高作用。结论 富集粘附细胞法可提高T淋巴细胞对神经髓鞘、PLP和MBP的增殖反应性 (MS和NC) ,多数情况使MS组和NC组的差别具有显著性的意义 ,对非髓鞘类抗原 (如TT)无这种作用。

CD4^+ T cell-mediated presentation of non-infectious HIV-1 virion antigens to HIV-specific CD8^+ T cells

Background The mechanism of chronic immune activation and impairment of HIV-specific immune responses during chronic infection is not fully understood. However, it is known that high immune activation leads to more rapid progression to AIDS. We hypothesize that CD4^＋ T cell-mediated viral antigen presentation contributes to this pathologic immune activation in HIV-infected individuals. Methods HIV-specific T cells, responding to noninfectious HIV-1 virions as antigen, were measured by flow cytometric assays. These experimental conditions reflect the in vivo condition where noninfectious HIV-1 represents more than 99% of the antigens. Results CD4^＋ T cells purified from HIV-infected individuals were capable of cross presenting exogenous noninfectious HIV-1 virions to HIV-1-specific CD8^＋ T cells. Cross presentation required the entry of HIV-1 to CD4^＋ T cells and antigen translocation from endoplasmic reticulum to the Golgi complex. Blocking CD4^＋ mediated activation of HIV-specific CD8^＋ T cells and redirecting the viral antigens to antigen presenting cells improved HIV-specific T cell responses. Contusions One possible cause of chronic immune activation and impairment of HIV-1 specific T cell responses is represented by HIV-1 harboring CD4^＋ T cells cross presenting HIV-1 antigen to activate CD8^＋ T cells. This new mechanism provides the first evidence that cross presentation of noninfectious HIV-1 virions play a role in the immunopathogenesis of HIV-1 infection.