T helper cell subsets require the expression of distinct costimulatory signals by antigen-presenting cells.

We examined the ability of macrophages and B cells to function as antigen-presenting cells (APCs) for murine TH1 and TH2 cloned T helper cell lines. Antigen presented by concanavalin A-elicited peritoneal macrophages or resting splenic B cells stimulated antigen-dependent proliferation of both T helper subsets. Paraformaldehyde fixation of the APCs following different conditions of activation indicated differential requirements for costimulatory signals by TH1 and TH2 cells. TH2 proliferative responses were strictly dependent on APC expression of IL-1. TH1 proliferation was dependent on APC expression of a non-IL-1 costimulatory signal present on freshly isolated macrophages and on splenic B cells activated with anti-immunoglobulin plus interferon gamma.     

Decay-accelerating factor regulates T-cell immunity in the context of inflammation by influencing costimulatory molecule expression on antigen-presenting cells

Recent studies have indicated a role of complement in regulating T-cell immunity but the mechanism of action of complement in this process remains to be clarified. Here we studied mice deficient in decay-accelerating factor (DAF), a key membrane complement regulator whose deficiency led to increased complement-dependent T-cell immune responses in vivo. By crossing OT-II and OT-I T-cell receptor transgenic mice with DAF-knockout mice, we found that lack of DAF on T cells did not affect their responses to antigen stimulation. Similarly, lack of DAF on antigen-presenting cells (APCs) of naive mice did not alter their T-cell stimulating activity. In contrast, APCs from DAF-knockout mice treated with inflammatory stimuli were found to be more potent T-cell stimulators than cells from similarly treated wild-type mice. Acquisition of higher T-cell stimulating activity by APCs in challenged DAF-knockout mice required C3 and C5aR and was correlated with decreased surface PD-L1 and/or increased CD40 expression. These findings implied that DAF suppressed T-cell immunity as a complement regulator in the context of inflammation but did not play an intrinsic role on T cells or APCs. Collectively, our data suggest a systemic and indirect role of complement in T-cell immunity.     

Adhesion molecule expression on B-cell chronic lymphocytic leukemia cells: malignant cell phenotypes define distinct disease subsets

Expression of surface adhesion molecules of the Ig superfamily (CD54 and CD58), of the integrin family (beta 1, beta 2, and beta 3 chains), of the selectin family (L-selectin), and of the lymphocyte homing receptor (CD44) was analyzed on B-cell chronic lymphocytic leukemia (B- CLL) cells from 74 patients. The aim of the study was the definition of phenotypically distinct disease subsets and the correlation of adhesion molecule phenotypes with clinical parameters. Expression of CD58 on B- CLL cells defined more advanced disease stages. In comparison with beta chain-positive cases, patients whose cells did not express beta 1, beta 2, and beta 3 integrin chains fell into the most favorable prognostic group, with lower lymphocytosis and the absence of splenomegaly, diffuse bone marrow infiltration, and therapy requirement. A novel finding was the expression of beta 3 chains on cells from a minority (12 of 74) of B-CLL cases. beta 3 chains were always coexpressed with beta 1 and beta 2 chains. Two-color immunofluorescence analyses of adhesion molecules such as alpha x beta 2 integrin (LeuM5) and L- selectin (Leu8) showed that these markers were detectable on variable proportions of leukemic cells, thus confirming the intraclonal phenotypic heterogeneity of B-CLL. Differences in the intensity of CD44 expression were also shown among the various B-CLL clones. Finally, no major variations were shown by comparison of adhesion molecule phenotypes of leukemic cells simultaneously obtained from blood and bone marrow, and of CD5+ versus CD5- clones.     

Expression and function of the murine B7 antigen, the major costimulatory molecule expressed by peritoneal exudate cells.

The murine B7 (mB7) protein is a potent costimulatory molecule for the T-cell receptor (TCR)-mediated activation of murine CD4+ T cells. We have previously shown that stable mB7-transfected Chinese hamster ovary (CHO) cells but not vector-transfected controls synergize with either anti-CD3 monoclonal antibody-induced or concanavalin A-induced T-cell activation, resulting ultimately in lymphokine production and proliferation. We now have generated a hamster anti-mB7 monoclonal antibody. This reagent recognizes a protein with an apparent molecular mass of 50-60 kDa. The mB7 antigen is expressed on activated B cells and on peritoneal exudate cells (PECs). Antibody blocking experiments demonstrate that mB7 is the major costimulatory molecule expressed by PECs for the activation of murine CD4+ T cells. This suggests an important role for mB7 during immune-cell interactions. We have also surveyed a panel of murine cell lines capable of providing costimulatory activity. Our results indicate that mB7 is the major costimulatory molecule on some but not all cell lines and that there may be additional molecules besides mB7 that can costimulate the activation of murine CD4+ T cells.     

The expression and function of costimulatory molecules B7H and B7-H1 on colonic epithelial cells

BACKGROUND & AIMS: Previous studies have suggested that intestinal epithelial cells (IECs) may function as antigen-presenting cells for CD4+ and CD8+ T cells. However, these cells fail to express conventional costimulatory molecules (CD80, CD86), leading to the possibility that antigen presented by normal IECs could result in anergy. Other members of the B7 family have recently been identified. B7h interacts with inducible costimulator (ICOS) on T cells and provides a positive signal, whereas B7-H1 and B7-DC interact with PD-1 and transmit an inhibitory signal. Our aim was to determine whether IECs express novel B7 family members and whether these molecules play a role in IEC:T-cell interactions. METHODS: B7h and B7-H1 expression was assessed in isolated IECs and IEC lines. The functional role of B7h and B7-H1 in the interaction between IECs and T cells was assessed in coculture experiments using purified anti-B7h or B7-H1 monoclonal antibodies (mAbs), B7h immunoglobulin (Ig), or B7-H1 fusion proteins. RESULTS: B7h and B7-H1 messenger RNA was detected in IEC lines and IECs from healthy controls and patients with inflammatory bowel disease (IBD). IECs from patients with IBD but not healthy controls expressed B7h and B7-H1 protein on their surface. Proliferation of IEC-stimulated T cells was inhibited only by B7h immunoglobulin treatment, whereas interferon gamma secretion in these cocultures was inhibited by both anti-B7h mAb and B7h Ig. No difference was seen between IBD or normal IEC populations. CONCLUSIONS: These data suggest that the B7h-ICOS costimulatory pathway may be important in IEC:T-cell interactions.     

Defective antigen-presenting cell function in patients with systemic lupus erythematosus: Role of the B7-1 (CD80) costimulatory molecule

Objective. Patients with systemic lupus erythematosus (SLE) who exhibit defective in vitro responses to recall antigens and normal responses to alloantigens have been shown to have an abnormality in antigenpresenting cell (APC) function. This study was undertaken to further characterize this defect in APC function in lupus patients. Methods. Mononuclear cells (MNC) from the peripheral blood of patients with SLE and from normal individuals were cultured in the presence of either recall antigen tetanus toxoid (TT), anti-CD3 (OKT3) monoclonal antibody, or alloantigens, and proliferative or interleukin-2 responses were assessed. Cell surface expression of B7-1 was assessed by flow cytometry. Results. MNC from all normal individuals and from 7 patients with SLE responded to both TT and alloantigen and were designated +/+. Twelve SLE patients did not respond to TT but did respond to alloantigen stimulation and were designated -/+. In both normal subjects and SLE patients, the ability to respond to OKT3 correlated strongly with the ability to respond to recall antigen. A defect in APC costimulatory function was suggested by data demonstrating that interferon-γ-induced expression of B7-1 was significantly reduced in SLE patients compared with controls. Neither controls nor SLE patients expressed detectable amounts of surface B7-1 molecule on resting APC. Defective recall and anti-CD3-stimulated responses could be enhanced in SLE patients in the presence of B7/BB1-transfected P815 murine mastocytoma cells underscoring an SLE-associated defect in costimulatory activity. However, nontransfected P815 cells were also able to enhance responses to OKT3 in -/+ patients; blocking experiments showed that this was mediated through an IgG Fc receptor-dependent mechanism. Conclusion. These data indicate that SLE-associated defects in APC function in vitro can be accounted for by abnormalities in APC surface membrane molecules such as B7, IgG Fc receptors, and possibly others.     

In situ expression and significance of B7 costimulatory molecules within tissues of human gastric carcinoma

AIM: To explore the role and significance of costimulatory molecules B7H1,B7H2 and ICOS within tissues of human gastric carcinoma and the possible mechanisms in tumor escape. METHODS: mRNA expressions of costimulatory molecules including B7H1,B7H2,ICOS and B7-1 in tissues of human gastric carcinoma were investigated by in situ hybridization using digoxigenin-labeled oligonucleotide-probes. The tissue of chronic gastric ulcer was used as a control. All data were analyzed by SPSS statistic software. RESULTS: At the site of gastric carcinoma, mRNA expression levels of B7H1, B7H2 and ICOS were much higher than that of B7-1. Their mRNA positive expression indexes were 0.512+/-0.333, 0.812+/-0.454, 0.702+/-0.359 and 0.293+/-0.253, respectively. The positively stained cells were mainly tumor infiltrating lymphocytes (TILs), and some tumor cells. The difference between them was greatly significant P<0.005. The mRNA expression levels of four molecules were not correlated to the pathological grade and matastasis of gastric carcinoma. CONCLUSION: ICOS-B7H costimulatory pathway may be predominant at the site of gastric carcinoma. B7-1mRNA might be the basis of ICOS-B7H interaction. ICOS-B7H interaction induces the production of IL-10 which inhibits the antitumor immune responses. Therefore, it is supposed that ICOS-B7H costimulatory pathway may be involved in the negative regulation of cell-mediated immune responses.     

Polarized expression and function of the costimulatory molecule CD58 on human intestinal epithelial cells

BACKGROUND & AIMS: Intestinal epithelial cells (IECs) can process foreign protein antigens and display antigenic peptides to CD4(+) T lymphocytes via HLA class II molecules. The purpose of this study was to determine the nature of the second, or costimulatory, signal provided by IECs. METHODS: We investigated surface expression of the costimulatory molecules CD58 (LFA-3), CD80 (B7-1), and CD86 (B7-2) by using flow cytometry, confocal microscopy, and vectorial biotinylation. Antibodies specific for CD58, CD80, and CD86 were used in blocking experiments to assess the role of these molecules in providing a costimulatory signal to CD4(+) T cells by IECs. RESULTS: CD58, but not CD80 or CD86, was observed to be expressed constitutively on both native IECs and in the IEC lines T84 and HT-29. The surface expression of CD58 was highly polarized and restricted to the basolateral surface of the cell. Antibodies against CD58, but not CD80 or CD86, inhibited the stimulation of CD4(+) T-cell proliferation mediated by IECs. CONCLUSIONS: CD58 is expressed by polarized IECs in a topologically restricted manner at the region of T-cell contact and can function as a costimulatory molecule in HLA class II-mediated antigen presentation.     

The B7-2 (B70) costimulatory molecule expressed by monocytes and activated B lymphocytes is the CD86 differentiation antigen

T-cell activation is initiated after T-cell receptor binding to antigen, but also requires interactions between costimulatory molecules expressed on antigen-presenting cells. An important costimulatory molecule expressed by monocytes and activated B lymphocytes has been recently identified and termed B7-2 or B70. Independently, a new Cluster of Differentiation was defined in the Fifth International Leukocyte Differentiation Antigen Workshop as CD86, a molecule predominantly expressed by monocytes and activated B lymphocytes. In this study, the two monoclonal antibodies that defined CD86, FUN-1 and BU-63, were shown to bind to cDNA transfected cells expressing B7- 2/B70. The FUN-1 monoclonal antibody also completely blocked the costimulatory activity of B7-2/B70 in functional assays. Therefore, the serologically defined CD86 differentiation antigen is the B7-2/B70 molecule.     

类风湿关节炎患者外周血B淋巴细胞共刺激分子的表达及其意义

目的 初步探讨类风湿关节炎(RA)患者免疫功能紊乱的机制。方法 采用流式细胞仪检测RA患者外周血B淋巴细胞共刺激分子CD80、CD86、CD40的表达并用ELISA检测RA患者血清和关节滑膜液中Th1细胞分泌的细胞因子白细胞介素(IL)-2、干扰素-γ和Th2细胞分泌的细胞因子IL-6、IL-10的水平。结果 RA患者外周血B淋巴细胞CD86表达比正常对照组明显下降(P＜0．01),B淋巴细胞CD40表达比正常对照组明显增多(P＜0．05),而B淋巴细胞CD80表达与正常对照组之间差异无显著性(P＞0．05),同时RA患者血清及滑膜液中IL-2、干扰素-γ的水平比正常对照组明显升高(P＜0．01或P＜0．05),而IL-6、IL-10的水平降低(P＜0．01或P＜0．05)。结论 B淋巴细胞共刺激分子CD86、CD40的异常表达可能与RA患者Th1／Th2细胞分泌的细胞因子失衡密切相关,这将为临床治疗RA提供新的思路。     

Clinical application value of soluble costimulatory molecule B7-H1 detection in colorectal cancer

正Objective To determine the level of soluble B7-H1(s B7-H1) in serum of patients with colorectal cancer(CRC),and to investigate its clinical application value in CRC. Methods 152 cases of CRC,57 cases of benign colorectal diseases and 59 healthy subjects were enrolled. ELISA was used to determine the s B7-H1 level in serum. The levels of carcinoembryonic antigen (CEA),     

The B7/BB1 antigen is expressed by Reed-Sternberg cells of Hodgkin's disease and contributes to the stimulating capacity of Hodgkin's disease-derived cell lines

The B7/BB1 molecule has recently been found to be expressed on professional antigen-presenting cells and to be the natural ligand for CD28 and CTLA-4 on T cells. On binding of B7/BB1, CD28 transduces a signal that synergizes with triggering of the T-cell antigen receptor, resulting in enhanced cytokine secretion. In view of the data supporting an antigen-presenting function of Reed-Sternberg cells, we evaluated the expression of B7/BB1 in lymph nodes affected by Hodgkin's disease. B7/BB1 was found to be strongly expressed by the Reed- Sternberg cells in all 47 cases of Hodgkin's disease studied. Moreover, Reed-Sternberg cells were frequently surrounded by CD28-expressing T cells. Evidence for a functional role of B7/BB1 on Reed-Sternberg cells was obtained by our findings that T-cell proliferation and interleukin- 2 (IL-2) production in the primary allogenic mixed lymphocyte reaction (MLR), using the B7/BB1-expressing Hodgkin's disease-derived cell lines L428 and KM-H2 as stimulators, could be partially blocked by adding anti-B7 monoclonal antibody. B7/BB1 expression was also evaluated in a group of non-Hodgkin's lymphomas (n = 46). Whereas B7/BB1 was not expressed by the neoplastic cells of most non-Hodgkin's lymphomas, including T-cell-rich B-cell lymphoma (n = 11), it was present on the neoplastic cells of anaplastic large-cell lymphoma (Ki-1 lymphoma) (n = 5) and follicular lymphoma (n = 4). Our data provide further evidence for an accessory cell function of Reed-Sternberg cells. The accessory cell function of Reed-Sternberg cells might lead to pronounced T-cell activation in vivo, which might contribute to the Hodgkin's syndrome. In addition, our study indicates that B7/BB1 may be a useful marker for differentiating Hodgkin's disease from morphologically similar conditions such as T-cell-rich B-cell lymphoma.     

B7-DC cross-linking restores antigen uptake and augments antigen-presenting cell function by matured dendritic cells

Dendritic cells (DCs) are classified in two states: immature DCs (iDCs), which perform sentinel functions, sampling for antigen and danger signals, and mature DCs (mDCs), which exhibit enhanced antigen-presenting functions but are no longer capable of acquiring antigen. We now describe DCs with a different activation phenotype: cells having the strong antigen-presenting functions of mDCs and the antigen-acquiring functions of iDCs. We have described an antibody that binds the costimulatory molecule B7-DC and activates DCs. The resulting phenotype is distinct from iDCs or mDCs matured by using Toll-like receptor (TLR) agonists. Ability to take up antigen increases, while expression of B71/2 costimulatory and MHC molecules remains unchanged. DCs matured with TLR agonists and then superactivated through B7-DC exhibit a previously unrecognized phenotype. These DCs recover the ability to take up antigen, which is normally lost after treatment with TLR-3 and TLR-9 agonists, yet retain the high expression of costimulatory and MHC molecules and strong antigen-presenting functions of mDCs. Immunization using TLR agonists and B7-DC XAb (cross-linking antibody) together as adjuvant resulted in substantially increased cytolytic T cell responses, particularly when minimal peptide antigens were used. By stimulating DCs with two distinct activation signals, a previously unrecognized phenotype exhibiting augmented antigen-presenting functions was obtained.     

Costimulation of T cells by B7-H2, a B7-like molecule that binds ICOS

This report describes a new human B7-like gene designated B7-H2. Cell surface expression of B7-H2 protein is detected in monocyte-derived immature dendritic cells. Soluble B7-H2 and immunoglobulin (Ig) fusion protein, B7-H2Ig, binds activated but not resting T cells and the binding is abrogated by inducible costimulator Ig (ICOSIg), but not CTLA4Ig. In addition, ICOSIg stains Chinese hamster ovary cells transfected with B7-H2 gene. By suboptimal cross-linking of CD3, costimulation of T-cell proliferation by B7-H2Ig is dose-dependent and correlates with secretion of interleukin (IL)-2, whereas optimal CD3 ligation preferentially stimulates IL-10 production. The results indicate that B7-H2 is a putative ligand for the ICOS T-cell molecule. (Blood. 2000;96:2808-2813)     

Human B cells that hyperexpress a triad of costimulatory molecules via avipox-vector infection: an alternative source of efficient antigen-presenting cells

Dendritic cells (DCs) are the most potent of the antigen-presenting cells (APCs). Preparation of sufficient numbers of mature DCs, however, is both costly and time-consuming. We have examined here the possibility of using an alternative source of APCs that would be easier to obtain, would not require extensive culture, and thus would be more applicable to human immunotherapy protocols. We show here that freshly isolated human B cells can be efficiently infected by a replication-defective fowlpox recombinant vector, designated rF-TRICOM (TRIad of COstimulatory Molecules), to markedly increase surface expression of the human costimulatory molecule B7-1 and moderately increase expression of intercellular adhesion molecule-1 (ICAM-1) and leukocyte function-associated antigen-3 (LFA-3). Peptide-pulsed rF-TRICOM-infected B cells were highly efficient in activating antigen-specific human T cells and shown to be superior to the use of CD40L in enhancing APC potency. Moreover, when infection of freshly isolated B cells with rF-TRICOM was combined with CD40L, a still further marked enhancement of the antigen-presenting potency was observed. Ex vivo-generated antigen-specific T cells activated in this manner might be applied to experimental protocols or used for adoptive transfer in immunotherapy protocols.     

小干扰RNA对淋巴细胞CD40表达的抑制作用

目的探讨体内转录法合成的小干扰RNA（siRNA）对淋巴细胞共刺激分子CD40基因表达的影响。方法设计并合成4条siRNA（si40-1、si40-2、si40-3、si40-4），在阳离子脂质体的介导下转染SD大鼠淋巴细胞。于转染48h收集细胞，半定量RT-PCR方法检测CD40mRNA，流式细胞仪检测CD40表达。结果流式细胞仪检测显示，si40-1、si40-2、si40-3、si40-4组的CD40表达抑制率分别为（21．10±1．54）％、（74．40±1．03）％、（41．80±0．86）％、（36．02±0．76）％，均明显高于空白对照组[（3．01±0．82）%]（P〈0．01），其中以si40-2的CD40抑制作用最强。半定量RT-PCR检测显示，与空白对照组比较．4组siRNA转染后淋巴细胞CD40mRNA均受到明显抑制伊〈0．01）．其中si40-2组的抑制作用最明显。结论sIRNA可特异性抑制淋巴细胞共刺激分子CD40基因的转录和表达，从而为进一步研究siRNA在移植免疫耐受及防治移植物抗宿主疾病（GVHD）方面的应用提供了理论和实验基础。     

Correlation of content of B cells and Leu7-positive cells with subtype and stage in lymphocyte predominance type Hodgkin's disease

Summary Cases of lymphocyte predominance type Hodgkin's disease were investigated using immunohistochemical methods and compared for morphological subtype and clinical stage. Cases of nodular paragranuloma showed a high, diffuse paragranuloma a moderate, and the mixed type a low, content of B cells. There was no significant correlation between B cell content and clinical stage. The number of Leu7+ cells was significantly increased in stage I of nodular paragranuloma. Hodgkin cells did not react with the CD15 antibody in most cases of paragranuloma but showed reactivity in the mixed type.