OBJECTIVE

To assess the safety and efficacy of a second course of treatment with a murine monoclonal antibody (MAb) to intercellular adhesion molecule 1 (ICAM-1; CD54) in active rheumatoid arthritis (RA).

METHODS

In an open-label study, 8 patients who had previously received a course of anti-ICAM-1 MAb received a second course.

RESULTS

The second course of therapy was associated with adverse effects suggestive of immune complex formation. Such adverse effects were not seen during the initial course of therapy. Clinical efficacy associated with the second course of therapy was less than that observed in the first course.

CONCLUSIONS

Repeated courses of therapy with a murine MAb to ICAM-1 would probably not be a useful therapeutic strategy in patients with RA, probably because of its immunogenicity.

We have shown previously that primary dendritic cells and monocytes express equal levels of CD14 but are distinguishable by the presence of CD2 on dendritic cells. CD2 is known to mediate the activation of T and natural killer (NK) cells through its interaction with CD58. CD2 epitopes recognized by anti-T111, -T112, and -T113 monoclonal antibodies (mAbs) are present on dendritic cells. Here we show that CD2 engagement significantly increases class II, costimulatory (CD40, CD80, CD86), adhesion (CD54, CD58), and CCR7 molecule expression on primary dendritic cells. Conversely, minimal or no change in the expression of the above antigens occurs on monocyte-derived dendritic cells, because these molecules are already maximally expressed. However, both kinds of dendritic cells release interleukin-1beta (IL-1beta) and IL-12 after CD2 engagement. Lastly, interference with dendritic cell CD2-T-cell CD58 engagement decreases naive CD4+CD45RA+ T-cell proliferation. Collectively, our results suggest another role of the CD2-CD58 pathway that allows nonimmune and immune cells to interact directly with dendritic cells and initiate innate and adaptive immune responses.

Previous studies have shown that human immunodeficiency virus type-1 (HIV-1) can incorporate several surface proteins of host origin. Recent findings indicate that host-encoded cell surface constituents retain their functionality when found embedded into the viral envelope. The primary objective of the current study was to define whether interaction between some specific virion-bound host proteins with their natural cognate ligands present on target cells could mediate intracellular signaling cascade(s). For this purpose, we have generated a whole series of isogenic virus stocks (NL4-3 backbone) bearing or not bearing on their surface foreign CD28, CD54 (ICAM-1), CD80 (B7-1) or CD86 (B7-2) proteins. Our results indicate that incubation of human T lymphoid cells with virions bearing host-derived B7-2 proteins and anti-CD3 antibody can potently activate HIV-1 long terminal repeat-driven gene expression. This up-regulating effect necessitates the involvement of nuclear factor-kappa B (NF-kappa B) and nuclear factor of activated T cells (NFAT) as revealed by the use of vectors coding for dominant negative versions of both transcription factors (i.e. I kappa B alpha S32A/36A and dnNFAT) and band shift assays. The increase of NF-kappa B activity was abolished when infection with B7-2-bearing HIV-1 particles was performed in the presence of the fusion protein CTLA-4 Ig suggesting that the interaction between virally embedded B7-2 and CD28 on the target cell is responsible for the observed NF-kappa B induction. The findings presented here provide the first demonstration that host-encoded proteins acquired by HIV-1 can mediate signal transduction events.

Endothelial cells are part of the normal bone marrow stroma. We have previously shown human umbilical cord blood (UCB) does not produce stroma in standard long-term cultures. Highly enriched (93-98%) UCB CD34+ cells were cultured for 6 weeks with interleukin-2 and conditioned medium from the 5637 carcinoma cell line (n = 4). The resulting 'fibroblast like' cells were shown to be endothelial by expression of von Willebrand factor (VWF), ICAM-1 (CD54), E-selectin (CD62E) and PECAM (CD31). Endothelial monolayers seeded with CD34+ UCB cells supported expansion of colony forming cells and CD34+ cells. We conclude that endothelial cell precursors circulate in UCB, and may be derived from the CD34+ cell fraction.

One group of sequence variants of Epstein-Barr virus is characterized by a 10-amino-acid deletion within the CTAR-2 functional domain of the latent membrane protein, LMP1. A role for this deletion in enhancing the tumorigenicity of the viral oncogene in rodent fibroblasts was recently demonstrated. We examined the effect of this deletion upon LMP1 function in four human lymphoid cell lines by using three natural variants of LMP1: the prototype B95.8 gene and the CAO and AG876 genes, both of which have codons 343 to 352 of the B95.8-LMP1 deleted. These experiments revealed that LMP1-mediated upregulation of CD40 and CD54 was markedly impaired (by 60 to 90%) with CAO-LMP1 compared with B95.8-LMP1. In contrast, the function of AG876-LMP1 was indistinguishable from that of B95.8-LMP1 in two lines and was only slightly impaired in the other two lines. Activation of NF-kappaB by CAO-LMP1 was not impaired in any of the lines; rather, activation of an NF-kappaB reporter by CAO-LMP1 was consistently about twofold greater than the activation with B95.8- or AG876-LMP1. Therefore, while the CAO-LMP1 is functionally distinct from the prototype B95.8-LMP1 in human lymphocytes, the 10-amino-acid deletion appears not to be directly responsible. This conclusion was confirmed by using a B95.8-LMP1 mutant with codons 343 to 352 deleted and chimerae of CAO- and B95.8-LMP1 in which the CTAR-2 domains of these genes were exchanged. Sequences outside the CTAR-2 domain were implicated in the distinct functional characteristics of CAO-LMP1 in human lymphoid cells.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is the prototypical aryl hydrocarbon receptor (AhR) ligand and a potent immunotoxicant. However, the mechanisms underlying TCDD-induced immunomodulation remain to be defined. Dendritic cells are professional antigen-presenting cells that constitutively express the AhR and are sensitive to TCDD-induced AhR activation. We hypothesized that AhR activation alters the differentiation and function of steady-state bone marrow-derived dendritic cells (BMDCs). To test this hypothesis, steady-state BMDCs from C57BL/6 mice were grown in the presence of TCDD or vehicle. TCDD-treated steady-state BMDCs (TCDD-BMDCs) displayed decreased expression of CD11c and CD11a, whereas increasing the frequency of major histocompatibility complex class II, CD86, CD80, and CD54. Similar phenotypic alterations were observed with the AhR ligands 6-formylindolo[3,2-b]carbazole and 2-(1H-indole-3'-carbonyl)-thiazole-4-carboxylic acid (ITE). TCDD-BMDCs from AhR(-/-) mice were refractory to TCDD-induced surface marker alterations, whereas TCDD-BMDCs from AhR(dbd/dbd) mice displayed similar phenotypic alterations as AhR(+/+) TCDD-BMDCs. Following lipopolysaccharide (LPS), cytosine-phosphate-guanine (CpG), or Imiquimod stimulation, TCDD-BMDCs secreted less interleukin (IL)-6, tumor necrosis factor-α (TNF-α), IL-10, and IL-12. TCDD also altered NF-κB family member-binding activity in unstimulated and LPS- or CpG-stimulated steady-state BMDCs. The internalization of the soluble antigens, ovalbumin, and acetylated low-density lipoprotein was decreased, whereas internalization of latex beads was increased in TCDD-BMDCs when compared with vehicle-BMDCs. TCDD-BMDCs displayed increased messenger RNA expression of the regulatory gene IDO2 and following LPS stimulation upregulated IDO1, IDO2, TGFβ1, and TGFβ3 gene expression. Additionally, TCDD-BMDCs increased the generation of CD4(+) CD25(+) FoxP3(+) Tregs in vitro in an IDO-dependent fashion. However, TCDD-treated BMDCs did not alter antigen-specific T-cell activation in vivo. Overall, TCDD-induced AhR activation alters the differentiation, activation, innate, and immunoregulatory function but not the T cell-activating capacity of steady-state BMDCs.

Endothelial cells express a wide spectrum of surface molecules involved in multiple vascular functions. We quantitatively determined an extensive immunologic phenotype of endothelial cells through a large panel of antibodies directed against i) well-known endothelial molecules CD31, CD34, CD49b, e, f, CD51, CD54, CD55, CD62E and P, CD105, CD106, HLA class I and HLA class II; ii) molecules defined by monoclonal antibodies newly clustered during the 6th workshop of Human Leukocyte Differentiation Antigen (HLDA) CD109, CD140b, CD141, CD142, CD143, CD144, CDw145, CD146 and CD147; iii) molecules defined by unclustered monoclonal antibodies. The expression of these molecules was quantified on human umbilical vein endothelial cells (HUVEC) cultured in resting conditions and after stimulation with IL-1beta (10 U/ml), TNF-alpha (10 ng/ml) and phorbol myristate acetate (60 ng/ml). Some molecules were constitutively expressed, and others were negative, which served to determine the basal phenotype. After cell stimulation, the molecules showed weak or strong expression modulation, leading to the definition of an activated phenotype. Changes in the kinetics and the amplitude of expression served to characterize poorly defined molecules and may be useful to determine their physiologic role. Also, we compared the phenotypes of endothelial cell lines EA.hy 926 and ECV 304 to that of HUVEC to assess their reliability as an endothelial cell model. Each cell line displayed a specific repertoire of molecules expressed at different levels, which could have significant implications for cell line behavior as endothelial cells.

IL-18 is secreted by a variety of cells such as epithelial cells, macrophages, and dendritic cells (DC), in particular, in areas of chronic inflammation. The effects of IL-18 are complex and not fully understood thus far. We sought to explore human DC as a new target for IL-18, since IL-18R expression has been described on myeloid cells such as macrophages and DC are likely to get in contact with IL-18 at sites of inflammatory reactions. We demonstrate the expression of the IL-18R on human DC in peripheral blood and epidermis, as well as monocyte-derived dendritic cells (MoDC). On MoDC, IL-18R expression is up-regulated by IFN-gamma. IL-18 strongly up-regulated CD54 on MoDC, whereas the effect on MHC class II, CD83, and CD86 was only moderate and the expression of CD40 and CD80 was not affected. MoDC primed with IL-18 did not increase their capacity to stimulate the proliferation or IFN-gamma production of autologous T cells. However, IL-18 had a direct migratory effect on MoDC as indicated by induction of filamentous actin polymerization and migration in Boyden chamber experiments. In epidermal DC, IL-18 was also able to induce filamentous actin polymerization. Therefore, IL-18 might represent a novel mechanism to recruit DC to areas of inflammation, in particular under Th1 cytokine conditions where IFN-gamma is increased such as psoriasis or inflammatory bowel diseases.

The latent membrane protein 1 (LMP-1) oncogene of Epstein-Barr virus (EBV) is believed to contribute to the development of many EBV-associated tumors, and there is evidence that sequence variation can affect some functions of LMP-1. Most studies have been restricted to the prototype B95.8 LMP-1 gene and genes isolated from EBV of nasopharyngeal carcinoma (NPC) patients. Here, we analyzed the signaling functions of LMP-1 from a panel of nine EBV isolates, including representatives of four defined groups of European LMP-1 variants (groups A to D [K. Sandvej, J. W. Gratama, M. Munch, X. G. Zhou, R. L. Bolhuis, B. S. Andresen, N. Gregersen, and S. Hamilton-Dutoit, Blood 90:323-330, 1997]) and Chinese NPC-derived LMP-1. Chinese and group D variants activated the transcription factor NF-kappa B two- to threefold more efficiently than B95.8 LMP-1, while Chinese, group B, and group D variants similarly activated activator protein 1 (AP-1) transcription more efficiently than did B95.8 LMP-1. However, there were no amino acid substitutions in the core binding regions for tumor necrosis factor receptor-associated adapter proteins known to mediate NF-kappa B and AP-1 activation. In contrast, despite sequence variation in the proposed Janus kinase 3 binding region, STAT activation was remarkably constant among the panel of LMP-1 variants. Analysis of the induction of CD54 (intercellular adhesion molecule 1) protein expression by the LMP-1 variants showed differences that did not correlate with either NF-kappa B or AP-1. Therefore, while the defined sequence variant groups do correlate with LMP-1 function, the results highlight the fact that the relationship between sequence variation and signaling function is extremely complex. It appears unlikely that one particular amino acid substitution or deletion will define a disease-associated variant of LMP-1.

In the present study, we addressed the role of intercellular adhesion molecule type 1 (ICAM-1/CD54) in neutrophil migration to inflammatory site and whether the inhibitory effect of nitric oxide (NO) upon the neutrophil rolling, adhesion and migration involves down-modulation of ICAM-1 expression through a cyclic GMP (cGMP) dependent mechanism. It was observed that neutrophil migration induced by intraperitoneal administration of endotoxin (LPS), carrageenan (Cg) or N-formyl peptide (fMLP) in ICAM-1 deficient (ICAM-1-/-) is similar to that observed in wild type (WT) mice. The treatment of mice with NO synthase (NOS) inhibitors, NG-nitro-l-arginine, aminoguanidine or with a soluble guanylate cyclase (sGC) inhibitor, ODQ enhanced LPS- or Cg-induced neutrophil migration, rolling and adhesion on venular endothelium. These parameters induced by LPS were also enhanced by 1400 W, a specific iNOS inhibitor, treatment. On the other hand, the treatment of the mice with S-nitroso-N-acetylpenicillamine (SNAP), an NO donor, reduced these parameters induced by LPS or Cg by a mechanism sensitive to ODQ pretreatment. The NOS inhibitors did not enhance LPS-, Cg- or fMLP-induced migration and adhesion in ICAM-1-/- mice. Moreover, genetic (iNOS-/- mice) or pharmacological inhibition of NOS or of sGC enhanced LPS-induced ICAM-1 expression on mesenteric microcirculation vessels of WT mice. By contrast, SNAP reduced the ICAM-1 expression by a mechanism dependent on cGMP. In conclusion, the results suggest that although during inflammation, ICAM-1 does not contribute to neutrophil migration, it is necessary for the down-modulatory effect of inflammation-released NO on the adhesion and transmigration of neutrophils. Moreover, these NO effects are mediated via cGMP.

Vgamma9Vdelta2 T cells respond to pyrophosphate antigens and display potent antitumour activity in vitro. We have investigated the potential of the most potent phosphoantigen known to activate Vgamma9Vdelta2 T cells, (E)-4-hydroxy-3-methyl-but-2 enyl pyrophosphate (HMB-PP), as an adjuvant for dendritic cell (DC)-based vaccines. A single stimulation of peripheral blood mononuclear cells with HMB-PP and IL-2 was sufficient to generate lines of effector memory Vgamma9Vdelta2 T cells that retained their cytolytic and cytokine secretion activities. These cells induced differentiation of DC into semi-mature antigen-presenting cells expressing CD86, CD11c, CD54, HLA-DR, CD83 and CD40, which secreted low levels of bioactive IL-12 but no IL-10. Vgamma9Vdelta2 T cells also strongly costimulated IL-12 release but inhibited IL-10 production by lipopolysaccharide (LPS)-stimulated DC. When substituted for Vgamma9Vdelta2 T cells, IFN-gamma did not induce full DC maturation but it augmented IL-12 and inhibited IL-10 release by LPS-stimulated DC, in a manner similar to HMB-PP-activated Vgamma9Vdelta2 T cells. Our findings indicate that Vgamma9Vdelta2 T cells, stimulated with nanomolar concentrations of HMB-PP, strongly promote T helper type 1 (Th1) responses through their ability to induce DC maturation and IL-12 secretion. This adjuvant activity may prove useful in DC-based cancer therapies.

OBJECTIVE

To investigate the variability in immunostaining for cytokines and cell adhesion molecules using multiple arthroscopically directed synovial biopsies from within a rheumatoid knee joint, quantitated by color video image analysis.

METHODS

Needle arthroscopic biopsies were taken from multiple sites (4-7 sites) around a knee joint in 8 patients with rheumatoid arthritis (RA). In 5 patients, immunoperoxidase staining for the cytokines tumor necrosis factor alpha (TNF-alpha), interleukin 8 (IL-8), and IL-1beta as well as the IL-1 receptor antagonist protein (IL-1ra) was performed. In 3 patients, immunoperoxidase staining for the cell adhesion molecules E-selectin (CD62E), P-selectin (CD62P), intercellular adhesion molecule 1 (ICAM-1, CD54), and platelet endothelial cell adhesion molecule (PECAM, CD31) was performed. Immunostaining was quantified using color video image analysis.

RESULTS

The overall probability of paired biopsies from the same RA knee joint being significantly different from each other due to sampling variation was at most 22% for cytokine staining (usually less than 10%). There were no significant differences between intrabiopsy and interbiopsy variability for cell adhesion molecule staining of the sublining and vessels.

CONCLUSIONS

The variability in cytokine and cell adhesion molecule staining within any single biopsy usually reflects the variability between biopsies taken from different sites in the same rheumatoid joint when the immunostaining is quantified using color video image analysis. Therefore, only a small number of synovial biopsies are required to accurately determine the cytokine and cell adhesion molecule expression in a single joint.

The expression of the intercellular adhesion molecule-1 (ICAM-1, CD54) seems to have an influence on the metastatic behaviour of tumour cells via immunological mechanisms. Recently, a soluble form of ICAM-1 was identified in physiological fluids. We analysed the serum levels of sICAM-1 in patients with non-small-cell lung cancer (NSCLC) and healthy individuals using a sandwich ELISA technique. Sera from 51 patients with NSCLC were tested for sICAM-1 (46 male, five female; age 38-81 years, median 64 years), 29 of whom presented with localized and 26 with metastatic disease. The control group consisted of 40 healthy individuals (20 smokers, 20 non-smokers). Immunohistochemical analysis of ICAM-1 in tumour cells was performed in 20 cases. Patients with NSCLC had significantly higher serum levels of sICAM-1 compared with healthy non-smokers (P = 0.00001) and smokers (P= 0.0328). Metastatic disease was associated with higher sICAM-1 than localized tumours (P = 0.0013). Only 11 out of 23 patients with localized NSCLC had sICAM-1 levels >300 ng ml(-1), compared with 25 out of 28 patients with metastatic disease. Histological expression of ICAM-1 was positively correlated with serum slCAM-1 (P = 0.0399). No difference was observed between histological tumour types with regard to sICAM-1 or NSCLC expression of ICAM-1. In sequential analysis (13 patients), rising sICAM-1 levels predicted a short-term fatal outcome (P = 0.0054) but, overall, sICAM-1 levels did not correlate with prognosis. In the control group, smokers showed significantly higher levels than non-smokers (P = 0.0016). In contrast to patients with NSCLC, sICAM-1 in the control group was correlated to the leucocyte count (r = 0.580, P = 0.003). In conclusion, serum levels of sICAM-1 seem to be associated with tumour burden and histological expression of ICAM-1 in patients with NSCLC. However, the (patho-) physiological role of ICAM-1 in NSCLC remains to be determined.

Nerve growth factor (NGF) receptors are expressed in different cell types outside the nervous system, and increasing evidence indicates that NGF can act as a regulatory molecule during inflammatory and immune responses. In this study, we show that triggering of the high-affinity NGF receptor TrkA with agonists protects monocytes from apoptosis induced by gliotoxin or UVB radiation. TrkA stimulation up-regulates the expression of the anti-apoptotic Bcl-2 family members, Bcl-2, Bcl-XL, and Bfl-1. On the other hand, TrkA stimulation does not change the expression of MHC, CD80, CD86, CD40, and CD54 molecules, nor the antigen-presenting function of monocytes. In addition, during in vitro monocyte to dendritic cell differentiation TrkA expression is progressively lost, suggesting that NGF selectively affects monocyte but not dendritic cell survival.

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of leukemic B cells concomitant with immunological abnormalities and depressed immune responses. The T cell abnormalities found in CLL patients are thought to increase the risk of infection and hamper immune recognition and elimination of leukemic cells. We evaluated whether providing signals through CD3 and CD28 would correct some of these T cell defects. PBMC were incubated with anti-CD3 and anti-CD28 mAbs conjugated to superparamagnetic beads for 12-14 days. This resulted in a 1400-fold increase in T cell numbers. Activated T cells expressed high levels of CD25, CD54, CD137, and CD154, and produced IFN-gamma, TNF-alpha, and GM-CSF. The mean T cell composition of cultures increased from approximately 6% to >90% and leukemic B cells decreased from a mean of approximately 85% to 0.1% or less. Leukemic B cells up-regulated expression of CD54, CD80, CD86, and CD95. Receptor up-regulation required direct cell contact with the activated T cells and could be blocked with anti-CD154 mAb, suggesting that the CD40-CD40L pathway helped mediate these effects. Poor T cell responses to allostimulation were corrected by the activation and expansion process. The skewing in the TCR repertoire returned to normal, or near normal following the culture process in eight of nine patients with abnormal TCR repertoires. Activated T cells had potent in vitro antileukemic effects in contrast to nonactivated T cells. Based upon these findings, a clinical trial has been initiated to test the potential therapeutic effects of T cells activated using this approach in patients with CLL.

BACKGROUND

Chronic alcohol use changes the brain's inflammatory state. However, there is little work examining the progression of the cytokine response during alcohol withdrawal, a period of profound autonomic and emotional upset. This study examines the inflammatory response in the central nucleus of the amygdala (CeA) and dorsal vagal complex (DVC), brain regions neuroanatomically associated with affective and cardiorespiratory regulation in an in vivo rat model of withdrawal following a single chronic exposure.

METHODS

For qRT-PCR studies, we measured the expression of TNF-α, NOS-2, Ccl2 (MCP-1), MHC II invariant chain CD74, and the TNF receptor Tnfrsf1a in CeA and DVC samples from adult male rats exposed to a liquid alcohol diet for thirty-five days and in similarly treated animals at four hours and forty-eight hours following alcohol withdrawal. ANOVA was used to identify statistically significant treatment effects. Immunohistochemistry (IHC) and confocal microscopy were performed in a second set of animals during chronic alcohol exposure and subsequent 48-hour withdrawal.

RESULTS

Following a chronic alcohol exposure, withdrawal resulted in a statistically significant increase in the expression of mRNAs specific for innate immune markers Ccl2, TNF-α, NOS-2, Tnfrsf1a, and CD74. This response was present in both the CeA and DVC and most prominent at 48 hours. Confocal IHC of samples taken 48 hours into withdrawal demonstrate the presence of TNF-α staining surrounding cells expressing the neural marker NeuN and endothelial cells colabeled with ICAM-1 (CD54) and RECA-1, markers associated with an inflammatory response. Again, findings were consistent in both brain regions.

CONCLUSIONS

This study demonstrates the rapid induction of Ccl2, TNF-α, NOS-2, Tnfrsf1a and CD74 expression during alcohol withdrawal in both the CeA and DVC. IHC dual labeling showed an increase in TNF-α surrounding neurons and ICAM-1 on vascular endothelial cells 48 hours into withdrawal, confirming the inflammatory response at the protein level. These findings suggest that an abrupt cessation of alcohol intake leads to an acute central nervous system (CNS) inflammatory response in these regions that regulate autonomic and emotional state.

Esters of fumaric acid have a long tradition in the treatment of psoriasis. Dimethylfumarate (DMF) is perceived as the main active substance. However, the molecular mechanisms of DMF action are not completely understood. Here, we investigate the effects of DMF on lymphocyte adhesion molecule expression in vitro and interactions with endothelial cells in vivo. DMF dose-dependently reduced superantigen-induced expression of CD25, human leukocyte antigen-DR, and cutaneous lymphocyte antigen by 27, 22, and 48% on CD3-positive cells, respectively. No change was observed for CD54, VLA-4, and P-selectin glycoprotein ligand-1. An enhancement of CD69 expression was noted (22%). DMF led to a significant reduction in binding of human peripheral blood mononuclear cells (PBMCs) to E-selectin (72%), P-selectin (36%), and vascular cell adhesion molecule-1 (33%) in vitro. Intravital microscopy of PBMCs in ear vasculature of wild-type and knockout mice showed that rolling was mainly P-selectin-dependent and could be reduced by 61% through DMF incubation. We provide early evidence that DMF affects adhesion molecule expression on human leukocytes and their rolling behavior in vivo, indicating that DMF directly affects the initial step of leukocyte extravasation.

Cell-mediated immune processes play a prominent role in the clinical manifestations of syphilis, a sexually transmitted disease of humans caused by spirochetal bacterium Treponema pallidum. The immune cell type that initiates the early immune response to T. pallidum thus far has not been identified. However, dendritic cells (DCs) are the first immune-competent cells to encounter antigens within skin or mucous membranes, the principal sites of early syphilitic infection. In the present study, immature DC line XS52, derived from murine skin, was utilized to examine T. pallidum-DC interactions and subsequent DC activation (maturation). Electron microscopy revealed that T. pallidum was engulfed by DCs via both coiling and conventional phagocytosis and was delivered to membrane-bound vacuoles. The XS52 DC line expressed surface CD14 and mRNA for Toll-like receptors 2 and 4, molecules comprising important signaling components for immune cell activation by bacterial modulins. Both T. pallidum and a synthetic lipopeptide (corresponding to the 47-kDa major membrane lipoprotein) activated the XS52 DC line, as indicated by the secretion of interleukin-12 (IL-12), IL-1beta, tumor necrosis factor alpha, and IL-6 and elevated surface expression of CD54. The combined data support the contention that DCs stimulated by T. pallidum and/or its proinflammatory membrane lipoproteins are involved in driving the cellular immune processes that typify syphilis.

Plasma cells obtained from bone marrow samples of 45 patients with MM, eight patients with MGUS, eight patients with Waldenström's macroglobulinaemia (WM), one patient with immunocytoma, and 12 controls were characterized by immunophenotyping, estimation of DNA content, and labeling index, as well as by morphological analysis. Plasma cells from 37/45 myeloma and 5/8 MGUS patients expressed CD38 and CD56 (N-CAM) on their surface but were negative for other NK cell-associated antigens such as CD16 (Fc gamma RIII) or CD2. All tumor cells of less-differentiated cell type (WM, immunocytoma) and normal polyclonal plasma cells were negative for CD56. CD56-specific mRNA was demonstrated in myeloma cells by northern blot analysis. Another adhesion molecule, ICAM-1 (CD54), was found on plasma cells from all patients and controls examined. Coexpression of CD19 (1/45), CD20 (9/45), or CD33 (3/45) was rare and CD10 with CD14 was expressed by a small tumor cell subpopulation of only one myeloma patient. The individual pattern of surface marker expression was not associated with a special-type myeloma protein isotype, stage or status of disease, LI or histological classification; however, a correlation between CD56 expression or histological classification and DNA content of the tumor cells was found.

IFN-gamma is critical for the protection against intracellular bacteria through activation of the antimicrobial machinery of phagocytes. Coxiella burnetii, the etiological agent of Q fever, is a strictly intracellular bacterium that inhabits monocytes/macrophages. We previously showed that IFN-gamma induced C. burnetii killing by promoting the apoptosis of infected monocytes. We show in this study that IFN-gamma-induced apoptosis of infected monocytes was characterized by a time- and dose-dependent activation of caspase-3. IFN-gamma-mediated caspase-3 activation and C. burnetii killing depend on the expression of membrane TNF. Indeed, TNF was transiently expressed on the cell surface of infected monocytes a few hours after IFN-gamma treatment. In addition, anti-TNF Abs inhibited IFN-gamma-mediated caspase-3 activation whereas soluble TNF had no effect on infected cells. Concomitantly, IFN-gamma induced homotypic adherence of C. burnetii-infected monocytes. The latter required the interaction of beta(2) integrins with CD54. When adherence was disrupted by pipetting, by a combination of Abs specific for CD11b, CD18, and CD54, or by an antisense oligonucleotide targeting CD18 mRNA, both cell apoptosis and bacterial killing induced by IFN-gamma were inhibited. Thus, adherence via CD54/beta(2) integrins together with membrane TNF are required to eliminate C. burnetii-infected cells through cell contact-dependent apoptosis. Our results reveal a new component of the antimicrobial arsenal mobilized by IFN-gamma against infection by intracellular bacteria.

1-methylnicotinamide (MNA) displays anti-inflammatory effects in patients with contact dermatitis, though the mechanisms involved remain unknown. Herein, we examined the anti-inflammatory effects of MNA and its parent molecule, nicotinamide, in the contact hypersensitivity reaction to oxazolone in CBA/J inbred mice. Feeding mice with MNA or nicotinamide (100 mg/kg, 10 days) resulted in the inhibition of the development of contact hypersensitivity reaction by 37% and 35%, respectively, as assessed by the magnitude of ear swelling. This effect was not associated with changes in the expression of adhesion molecules (CD49d(+) and CD54(+)) on CD4(+) and CD8(+) oxazolone-specific T lymphocytes, the major cell component of an inflammatory infiltrate in contact hypersensitivity reaction. Furthermore, in the adoptive transfer model of contact hypersensitivity reaction, pretreatment of mice (recipients of oxazolone-specific T cells), with MNA, resulted in a remarkable anti-inflammatory effect (inhibition of contact hypersensitivity reaction by 66%). Interestingly, in the presence of prostanoid IP receptor antagonist R-3-(4-fluoro-phenyl)-2-[5-(4-fluoro-phenyl)-benzofuran-2-ylmethoxycarbonylamino]-propionic acid (RO-3244794) (10 mg/kg) the MNA was inactive. In summary, pretreatment with MNA profoundly attenuated contact hypersensitivity reaction in vivo. In particular, the vessel dependent phase of contact hypersensitivity reaction was affected, in spite of the fact that MNA did not alter the expression of adhesive molecules on oxazolone-specific T lymphocytes. However, the anti-inflammatory action of MNA was completely reversed by the antagonist of prostanoid IP receptor. Accordingly, our results demonstrate for the first time that anti-inflammatory properties of MNA are linked to endothelial, PGI(2)-mediated mechanisms.

Intercellular adhesion molecule 1 (ICAM-1) (CD54) is an adhesion molecule of the immunoglobulin superfamily. The interaction between ICAM-1 on B lymphocytes and leukocyte function-associated antigen 1 on T cells plays a major role in several aspects of the immune response, including T-dependent B cell activation. While it was originally believed that ICAM-1 played a purely adhesive role, recent evidence suggests that it can itself transduce biochemical signals. We demonstrate that cross-linking of ICAM-1 results in the up-regulation of class II major histocompatibility complex, and we investigate the biochemical mechanism for the signaling role of ICAM-1. We show that cross-linking of ICAM-1 on the B lymphoma line A20 induces an increase in tyrosine phosphorylation of several cellular proteins, including the Src family kinase p53/p56(lyn). In vitro kinase assays showed that Lyn kinase was activated within 1 min after ICAM-1 cross-linking. In addition, ICAM-1 cross-linking resulted in activation of Raf-1 and mitogen-activated protein kinases, as determined by gel mobility shift. Activation of these kinases may represent important components in the cascade of signals that link ICAM-1 to various ICAM-1-elicited cellular responses. These data confirm the important role of ICAM-1 as a signaling molecule in B cell activation.

Solid tumors may secrete factors that mediate immune suppression in patients. We investigated the effect of supernatants from 25 human tumor cell lines on T-lymphocytes from healthy donors. A profound inhibition of proliferation, cytokine secretion and cytotoxic activity was seen when T-cells were cultured in concentrated tumor supernatants from 6 cell lines fractionated into high (>100 kDa) m.w. molecules. Interestingly, the inhibitory effects were reversed when the tumor supernatant was removed. Cell cycle studies of inhibited T-cells showed most of them were growth arrested in the G(0)/G(1) phase similar to naïve T-cells. In addition, these T-cells did not express IL2-receptors and expression of CD54 (ICAM-1) and CD58 (LFA-3) resembled that of resting T-cells. Protein gel electrophoresis of the tumor supernatants and western blot analysis demonstrated the presence of soluble MUC1 in the inhibitory tumor supernatants but not in control supernatant. Most importantly, depletion of soluble MUC1 by immunoprecipitation from the tumor supernatants neutralized the inhibitory effects on T-lymphocytes. Therefore, our results show that MUC1 shed by cultured epithelial tumor cells mediates inhibition of T-cell proliferation and function by inducing cell growth arrest.

Chronic lymphocytic leukemia (CLL) results in the accumulation of B cells, presumably reflecting the selection of malignant cell precursors with Ag combined with complex alterations in protein activity. Repeated BCR stimulation of normal B cells leads to anergy and CD5 expression, both of which are features of CLL. Because CD5 is phosphorylated on tyrosine following BCR engagement and negatively regulates BCR signaling in normal B cells, we investigated its phosphorylation status and found it to be naturally phosphorylated on tyrosine but not on serine residues in CLL samples. To analyze the role of CD5, we established a B cell line in which CD5 is phosphorylated. Gene profiling of vector vs CD5-transfected B cells pointed out gene groups whose expression was enhanced: Apoptosis inhibitors (BCL2), NF-kappaB (RELB, BCL3), Wnt, TGFbeta, VEGF, MAPKs, Stats, cytokines, chemokines (IL-10, IL-10R, IL-2R, CCL-3, CCL-4, and CCR7), TLR-9, and the surface Ags CD52, CD54, CD70, and CD72. Most of these gene groups are strongly expressed in CLL B cells as compared with normal B cells. Unexpectedly, metabolic pathways, namely cholesterol synthesis and adipogenesis, are also enhanced by CD5. Conversely, CD5 inhibited genes involved in RNA splicing and processing, ribosome biogenesis, proteasome, and CD80 and CD86 Ags, whose expression is low in CLL. Comparison of CD5- vs tailless CD5-transfected cells further demonstrated the role of CD5 phosphorylation in the regulation of selected genes. These results support a model where CLL cells are chronically stimulated, leading to CD5 activation and cell survival. In addition to CD5 itself, we point to several CD5-induced genes as potential therapeutic targets.