The basis for the immunoregulatory role of macrophages and other accessory cells

A T cell receptor flattens a bulged antigenic peptide presented by a major histocompatibility complex class I molecule

Plasticity of the T cell receptor (TCR) is a hallmark of major histocompatibility complex (MHC)-restricted T cell recognition. However, it is unclear whether interactions of TCR and peptide-MHC class I (pMHCI) always conform to this paradigm. Here we describe the structure of a TCR, ELS4, in its non-ligand-bound form and in complex with a prominent 'bulged' Epstein-Barr virus peptide bound to HLA-B(*)3501. This complex was atypical of previously characterized TCR-pMHCI interactions in that a rigid face of the TCR crumpled the bulged antigenic determinant. This peptide 'bulldozing' created a more featureless pMHCI determinant, allowing the TCR to maximize MHC class I contacts essential for MHC class I restriction of TCR recognition. Our findings represent a mechanism of antigen recognition whereby the plasticity of the T cell response is dictated mainly by adjustments in the MHC-bound peptide.

Lipopolysaccharide-induced IL-1 beta production by human uterine macrophages up-regulates uterine epithelial cell expression of human beta-defensin 2

The uterine endometrium coordinates a wide spectrum of physiologic and immunologic functions, including endometrial receptivity and implantation as well as defense against sexually transmitted pathogens. Macrophages and epithelial cells cooperatively mediate innate host defense against bacterial invasion through the generation of immunologic effectors, including cytokines and antimicrobial peptides. In this study, we demonstrate that stimulation of peripheral blood monocytes and uterine macrophages with bacterial LPS induces the production of biologically active proinflammatory IL-1beta. High doses of estradiol enhance LPS-induced IL-1beta expression in an estrogen receptor-dependent manner. Furthermore, both peripheral blood monocyte- and uterine macrophage-derived IL-1beta induce secretion of antimicrobial human beta-defensin 2 by uterine epithelial cells. These data indicate dynamic immunologic interaction between uterine macrophages and epithelial cells and implicate a role for estradiol in the modulation of the immune response.

Lysophospholipid transacetylase in the regulation of PAF levels in human monocytes and macrophages

The transacetylase (TA), reported to be identical to platelet-activating factor (PAF) acetylhydrolase (II), is a multifunctional enzyme with three catalytic activities: lysophospholipid transacetylase (TA(L)), sphingosine transacetylase (TA(S)), and acetylhydrolase (AH). We report that TA(L) activity participates in the control of PAF levels in monocytes and macrophages and that its regulation differs in these two types of cells. In monocytes, LPS or granulocyte-macrophage colony-stimulating factor (GM-CSF) specifically increased the TA(L) activity. Western blot analysis and enzyme assays on immunoprecipitates revealed that the increased activity can be ascribed to PAF-AH (II) and that both translocation from cytosol to membranes and p38/ERKs-mediated phosphorylation regulate the enzyme activation. Instead, in macrophages differentiated in vitro from monocytes by incubation with FCS, an increase of both TA(L) and AH activities was observed. Moreover, activation of ERKs and p38 MAP kinase was not required for the up-regulation of PAF-AH (II) in differentiated macrophages. The differences observed in macrophages as compared to monocytes can be explained by 1) p38/ERKs-independent phosphorylation of PAF-AH (II) and 2) appearance of plasma PAF-AH in the course of macrophage differentiation.

Assessment of usefulness of J774A.1 macrophages for the assay of IL-1β promoter activity

Existing data indicate that the increase of il-1beta gene expression can be a promising marker of Langerhans cells activation after exposure to contact sensitizers. In this study, we were interested in development of an alternative in vitro screening test detecting such sensitizers. Two IL-1beta reporter constructs containing the enhanced green fluorescent protein (GFP) gene and mouse IL-1beta promoter fragments of varying lengths (-500 bp and -4093 bp) were used for transient transfections of J771A.1 murine monocyte-macrophage cells. As a result of the transfections performed using Lipofectamine reagent we did not observe any GFP fluorescence after stimulation of the cells with LPS as well as known sensitizers (potassium tetrachloroplatinate, dinitrochlorobenzene and nickel sulfate). Low transfection efficiency of J774A.1 cells (less than 0.1%) was confirmed using control plasmid containing GFP gene under the control of cytomegalovirus promoter. The fact that, using the same conditions, we were able to transfect murine fibroblasts 3T3-L1 with the control plasmid very efficiently, may support the theory of high metabolic activity of macrophages being responsible for the extremely low transfection efficiency. These data suggest limited suitability of J774A.1 cell line for transient transfections using cationic liposomes.

Selective activation of adrenergic β1receptors induces heme oxygenase 1 production in RAW264.7 cells

We hypothesized that catecholamines through beta-adrenoceptor might modulate macrophage function. We showed that isoproterenol concentration-dependently induced HO-1 production through beta(1)-but not beta(2)-adrenoceptor. Production was increased by forskolin and inhibited by pretreatment with the PKA inhibitor, H-89. Furthermore, induction of HO-1 by isoproterenol effectively protected RAW264.7 cells from effects of glucose oxidase treatment, which was abrogated either by HO-1 inhibitor, ZnPP IX and beta-adenoceptor antagonist, propranolol. Thus, stimulation of HO-1 production through beta(1)-adenoceptors, and via the PKA pathways by isoproterenol, can enable RAW264.7 cells to resist oxidant stress, suggesting that catecholamine hormones may be necessary, at least, to maximize defending role of macrophages.

Structural and functional aspects of the liver and liver sinusoidal cells in relation to colon carcinoma metastasis

Nowadays, liver metastasis remains difficult to cure. When tumor cells escape and arrive in the liver sinusoids, they encounter the local defense mechanism specific to the liver. The sinusoidal cells have been widely described in physiologic conditions and in relation to metastasis during the past 30 years. This paper provides an “overview” of how these cells function in health and in diseases such as liver metastasis.

Prior exposure to the carrier regulates rat immune responses to a conjugate vaccine

Small vaccine antigens including peptides generally need to be linked to larger molecules or carriers in order to induce high levels of immune responses. The potential of unwanted immune responses to the carriers represents a major drawback for the conjugated vaccines. The carriers could also regulate the immune responses to the haptens and these effects need to be prevented in order to achieve adequate responses to the vaccines. We examined means to reduce the unwanted reactions to the carrier. For this purpose, we investigated whether prior exposure of rats to a human IgG(1) (hIgG(1)) carrier would affect their subsequent responses to an OVA peptide (i.e., OVA(173-196)). Prior exposure to the hIgG(1) carrier did not affect the T cell responses to the peptide antigen. However, IgG(1) Ab responses to the peptide antigen were enhanced while IgE Abs were reduced. These results show that responses to the hapten are not systematically relevant to the carrier pre-immunization and that the conjugate could achieve desired responses by selective immune responses suppression. Such models of vaccines with enhanced anti-hapten responses and reduced levels of potentially harmful responses could be of great interest for the development of new immune therapies.

Yersinia rLcrV and rYopB inhibits the activation of murine peritoneal macrophages in vitro

Yersinia antigenic proteins LcrV and YopB are translocators of effector Yops in type III secretion system. Recently, we have reported that rLcrV and rYopB inhibit the production of TNF-alpha, IFN-gamma, and IL-12 in murine peritoneal macrophages. It was also demonstrated that IL-10 and TLR2 signaling pathways and inhibition of MAPK cascade is involved in rLcrV- and rYopB-induced immunomodulation. In the present study, it is reported that rLcrV and rYopB inhibited the LPS-induced production of IL-1beta in macrophages. Pretreatment of macrophages with rLcrV and rYopB also inhibited the LPS-induced transcription of IL-6 but not of GM-CSF. However, the transcription of chemokines like MCP-1, MIP-1alpha, MIP-1beta, and RANTES were inhibited by rLcrV and rYopB. Both proteins also affected the cytoskeleton and lipid rafts in macrophages. It is further observed that IL-10 antibodies abrogated the rLcrV- and rYopB-induced inhibition of IL-1beta production in LPS-treated macrophages. The data, therefore, suggests a possible role of IL-10 in rLcrV and rYopB mediated inhibition of LPS-induced production of IL-1beta in macrophages.

17-Beta estradiol enhances prostaglandin E2 production in human U937-derived macrophages

Prostaglandins (PGs) are potent eicosanoid lipid mediators that have been implicated in numerous homeostatic functions and inflammation. Estrogens have been shown to regulate the expression of genes in lipid metabolism in many cellular systems. In this study, the activation of macrophages and the modulation of PG release by estrogens were examined. The effects of 17-alpha and 17-beta estradiols, phytoestrogen Genistein and several selective estrogen receptor modulators on the release of PGE2 were investigated in human U937-derived macrophages. 17-Beta estradiol caused an enhancement of PGE2 production in a time- and dose-dependent manner. Treatment of macrophages with 17-beta estradiol elicited an increased arachidonic acid (AA) release and an up-regulation of both cyclooxygenesis-1 and cyclooxygenesis-2 enzymes at both the transcript and protein levels. In addition, immunostaining of nuclear estrogen receptor alpha and the observation of ICI182 780 blockade of PGE2 production indicated that 17-beta estradiol-induced PGE2 release was mainly through nuclear estrogen receptor alpha.

Phospholipid diversity: Correlation with membrane–membrane fusion events

The transport of various metabolically important substances along the endocytic and secretory pathways involves budding as well as fusion of vesicles with various intracellular compartments and plasma membrane. The membrane-membrane fusion events between various sub-compartments of the cell are believed to be mainly mediated by so-called "fusion proteins". This study shows that beside the proteins, lipid components of membrane may play an equally important role in fusion and budding processes. Inside out (ISO) as well as right side out (RSO) erythrocyte vesicles were evaluated for their fusogenic potential using conventional membrane fusion assay methods. Both fluorescence dequenching as well as content mixing assays revealed fusogenic potential of the erythrocyte vesicles. Among two types of vesicles, ISO were found to be more fusogenic as compared to the RSO vesicles. Interestingly, ISO retained nearly half of their fusogenic properties after removal of the proteins, suggesting the remarkable role of lipids in the fusion process. In another set of experiments, fusogenic properties of the liposomes (subtilosome), prepared from phospholipids isolated from Bacillus subtilis (a lower microbe) were compared with those of erythrocyte vesicles. We have also demonstrated that various types of vesicles upon interaction with macrophages deliver encapsulated materials to the cytosol of the cells. Membrane-membrane fusion was also followed by the study, in which a protein synthesis inhibitor ricin A (that does not cross plasma membrane), when encapsulated in the erythrocyte vesicles or subtilosomes was demonstrated to gain access to the cytosol.

Macrophage population dynamics within fetal mouse fibroblast cultures derived from C57BL/6, CD-1, CF-1 mice and interleukin-6 and granulocyte colony stimulating factor knockout mice

In vitro models of macrophage growth, differentiation, and function are needed to facilitate the study of their biology as important immune facilitator cells and as frequent targets of bacterial and viral infection. A simple method for the selective expansion and continuous culture of mouse macrophages from primary explant cultures of mouse embryonic tissue is described. Culture in Dulbecco modified Eagle medium (DMEM) low-glucose (1 g/L) formulation (DMEM/L) inhibited fibroblast growth. In contrast, macrophages continued to proliferate in the presence of DMEM/L when in contact with the fibroblasts. Alternating growth in high-glucose DMEM with DMEM/L produced a 1.16- to 2.1-fold increase (depending on mouse strain) in the percentage of macrophages within the cell culture in comparison with culturing in DMEM with high glucose exclusively. Macrophage yields of over 1 million cells/T12.5 flask were achieved by passages 3-4, and, thereafter, declined over the next 5-10 passages. The peak percentage of macrophages within a culture varied depending on the strain of mouse (C57BL/6, CD-1, and CF-1 and two knockout C57BL/6 strains deficient in either interleukin-6 [IL-6] or granulocyte colony stimulating factor [GCSF]). The GCSF (-/-)-derived cultures had the lowest peak macrophage content (30%) and CD-1 the highest content (64.9%). The IL-6 (-/-) and CD-1 cultures appeared to spontaneously transform to create cell lines (IL6MAC and CD1MAC, respectively) that were composed of 50-75% macrophages. The macrophages were phagocytic and were positive for CD14, acetylated low-density lipoprotein receptors, and F4-80 antigen. Light and electron microscopy showed that the cultured macrophages had in vivo-like morphological features, and they could be plated to high purity by differential attachment to petri dishes in serum-free medium.

HLA alleles in frequently relapsing steroid-dependent and -resistant nephrotic syndrome in Egyptian children

The association between HLA class II antigens and childhood primary nephrotic syndrome has been reported in different populations. To investigate this association in Egyptian children, DRB1 alleles were typed by DNA polymerase chain reverse hybridization in 20 frequent relapsers/steroid-dependent and 14 steroid-resistant children with minimal change nephrotic syndrome (MCNS) and 121 unrelated healthy controls from the northern part of Egypt. The strength of the association was expressed as the relative risk (RR) estimated by the odds ratio. The DRBI*07011 allele frequency was significantly higher among patients than controls (78.9% vs. 16%, Pc <0.001). The etiological fraction (EF) was high at 0.75 [RR=20.1, confidence interval (CI)=6.0-66.7]. Similarly, patients with steroid-resistant MCNS had a higher frequency of the DRBI*07011 allele than controls (64.3% vs. 16.5%, P c<0.001). The EF was high at 0.57 (RR=9.6, CI 2.9-31.7). In the whole group of patients the frequency of DRBI*11 alleles was low compared with controls (11.4% vs. 32.2%, P =0.02), but was not significant when P was corrected. In conclusion, the DRBI*07011 allele confers susceptibility to a frequently relapsing and steroid-dependent or steroid-resistant course of childhood MCNS. These patterns of the disease seem to have the same immunogenetic components.

Role of lung macrophages on susceptibility to respiratory infection following short-term moderate exercise training

Moderate exercise training is associated with a decreased risk for upper respiratory tract infection in human and animal studies, but the mechanisms have not been elucidated. Lung macrophages play an important role in resistance to respiratory infection, and moderate exercise can enhance macrophage antiviral resistance, but no studies have directly tested the role of lung macrophages in this response. This study tested the effect of lung macrophage depletion on susceptibility to infection following short-term moderate exercise training. Mice were assigned to one of four groups: exercise (Ex) and resting controls (Con) with and without clodronate encapsulated liposomes (CL2MDP-lip). Ex mice ran for 1 h on a treadmill for 6 days at 36 m/min, 8% grade. Fifteen minutes following exercise or rest on the last day of training, mice were intranasally inoculated with a standardized dose of herpes simplex virus type 1. Clodronate (Ex-CL2MDP-lip and Con-CL2MDP-lip) or PBS liposomes (Ex-PBS-lip and Con-PBS-lip) (100 μl) were intranasally administered following exercise or rest on the 4th day of training and again on the 4th day postinfection. Morbidity, mortality, and symptom severity were monitored for 21 days. Exercise decreased morbidity by 36%, mortality by 61%, and symptom severity score on days 5–7 ( P < 0.05). Depletion of lung macrophages negated the beneficial effects of moderate exercise. This was indicated by no differences between Ex-CL2MDP-lip and Con-PBS-lip in morbidity (89 vs. 95%), mortality (79 vs. 95%), or symptom severity. Results indicate that lung macrophages play an important role in mediating the beneficial effects of moderate exercise on susceptibility to respiratory infection.

Studies on the mechanism of caffeine action in alveolar macrophages: caffeine elevates cyclic adenosine monophosphate level and prostaglandin synthesis

We have previously reported that the effects of caffeine on alveolar macrophages are dose-dependent; thus, at low concentrations caffeine prevents apoptosis and at moderate concentrations, the cells proceed into apoptosis. In the current study, the mechanism of caffeine action via prostaglandin synthesis and cyclic adenosine monophosphate (cAMP) was investigated using moderate concentrations of caffeine. The results show that the combination of caffeine with indomethacin, an inhibitor of prostaglandin synthesis, mediated caffeine's effect by increasing cellular viability and lowering superoxide anion production and DNA fragmentation. However, addition of exogenous prostaglandin E2 (PGE2) to the culture in the presence of caffeine had the opposite effect, in which the viability was decreased and anion superoxide production was increased. Incubation of macrophages with exogenous dibutyryl cAMP showed nearly similar effects to caffeine. At low concentrations (<50 micromol/L), higher viability and lower superoxide production pattern were evident and at higher concentrations (>50 micromol/L) the cells proceeded into apoptosis. Therefore, it is suggested that caffeine exerts its effects on macrophages by altering cAMP level and prostaglandin synthesis.

Effect of rLcrV and rYopB from Yersinia pestis on murine peritoneal macrophages in vitro

The interaction between macrophages and bacterial pathogens is crucial in the pathogenesis of infectious diseases. The 70 kb plasmid encodes low calcium response V (LcrV) or V antigen and a group of highly conserved yersinia outer proteins (Yops) are essential for full virulence. In present study, we investigated the effect of rLcrV and rYopB on macrophage functions in vitro. It is observed that rLcrV and rYopB inhibited the LPS induced expression of TNF-alpha, IFN-gamma, KC, IP-10, and IL-12 in macrophages. rLcrV and rYopB caused increased expression of IL-10 and TLR2, whereas inhibited TLR4 expression in LPS treated macrophages. IL-10 and TLR2 antibodies reversed the rLcrV and rYopB induced inhibition of TNF-alpha production by LPS treated macrophages, whereas IL-4 and TLR4 antibodies had no effect. Our data suggests a possible role of IL-10 and TLR2 in rLcrV and rYopB mediated inhibition of macrophage function.

HLA-B27-associated reactive arthritis: pathogenetic and clinical considerations

Current evidence supports the concept that reactive arthritis (ReA) is an immune-mediated synovitis resulting from slow bacterial infections and showing intra-articular persistence of viable, non-culturable bacteria and/or immunogenetic bacterial antigens synthesized by metabolically active bacteria residing in the joint and/or elsewhere in the body. The mechanisms that lead to the development of ReA are complex and basically involve an interaction between an arthritogenic agent and a predisposed host. The way in which a host accommodates to invasive facultative intracellular bacteria is the key to the development of ReA. The details of the molecular pathways that explain the articular and extra-articular manifestations of the disease are still under investigation. Several studies have been done to gain a better understanding of the pathogenesis of ReA; these constitute the basis for a more rational therapeutic approach to this disease.

Theiler's virus infection: a model for multiple sclerosis

Both genetic background and environmental factors, very probably viruses, appear to play a role in the etiology of multiple sclerosis (MS). Lessons from viral experimental models suggest that many different viruses may trigger inflammatory demyelinating diseases resembling MS. Theiler's virus, a picornavirus, induces in susceptible strains of mice early acute disease resembling encephalomyelitis followed by late chronic demyelinating disease, which is one of the best, if not the best, animal model for MS. During early acute disease the virus replicates in gray matter of the central nervous system but is eliminated to very low titers 2 weeks postinfection. Late chronic demyelinating disease becomes clinically apparent approximately 2 weeks later and is characterized by extensive demyelinating lesions and mononuclear cell infiltrates, progressive spinal cord atrophy, and axonal loss. Myelin damage is immunologically mediated, but it is not clear whether it is due to molecular mimicry or epitope spreading. Cytokines, nitric oxide/reactive nitrogen species, and costimulatory molecules are involved in the pathogenesis of both diseases. Close similarities between Theiler's virus-induced demyelinating disease in mice and MS in humans, include the following: major histocompatibility complex-dependent susceptibility; substantial similarities in neuropathology, including axonal damage and remyelination; and paucity of T-cell apoptosis in demyelinating disease. Both diseases are immunologically mediated. These common features emphasize the close similarities of Theiler's virus-induced demyelinating disease in mice and MS in humans.

Endogenous production of TNFalpha is a potent trigger of NFkappaB activation by irradiation in human monocytic cells THP-1

Irradiation causes DNA damage and induces neoplastic transformation. In response to irradiation, cells induce genes or activate proteins that protect themselves from the external insult. Nuclear factor kappaB (NFkappaB) activates transcription of target genes and plays important roles in inflammation. We studied the mechanism(s) for activation of NFkappaB by irradiation in human monocytic cells THP-1. Gel mobility shift assays showed that irradiation stimulated the NFkappaB-DNA binding activity of nuclear extracts from these cells. Western blot analysis using polyclonal antibody against phosphorylated IkappaB protein showed that irradiation increased the levels of phosphorylated IkappaB. The production of tumor necrosis factor alpha (TNFalpha) was stimulated by irradiation in these cells. Treatment with exogenously added TNFalpha also stimulated the NFkappaB binding activity with concomitant degradation of IkappaB. Further study found that the activation of NFkappaB by irradiation was inhibited by a neutralizing anti-TNFalpha antibody. Macrophages from TNFalpha-deficient mice were also defective in the irradiation-induced activation of NFkappaB. These results indicate that endogenous production of TNFalpha in macrophages/monocytes is required for NFkappaB activation by irradiation. Our data also suggest that TNFalpha in monocytes/macrophages exposed to irradiation is involved in signal transduction network initiation.

Restimulation of tumour-specific immunity in a patient with AML following injection with B7-1 positive autologous blasts

Leukaemic blast cells lack co-stimulatory molecules such as B7, necessary for T-lymphocyte activation. We have used modified CD80+ (B7-1+) tumour cells, with autologous, IL-2 producing, stromal marrow cells in a series of subcutaneous vaccinations to provide a localised environment for the enhancement of cytotoxic T-lymphocytes (CTL) in a patient with acute myeloid leukaemia (AML). Localised inflammation was evident after the fifth and sixth injections with a reduction in the number of circulating blasts in the following 2 weeks. Peripheral blood in vitro CTL activity increased 36-47% after five injections.CD4 T-lymphocytes (5.7%) expanded from post-injection skin biopsies, expressed intracellular IFNgamma and perforin when exposed to autologous B7-1+ blasts and when co-cultured with either B7-1+ or unmanipulated autologous blast cells showed proliferative responses. In this patient, co-injection of B7-1+ tumour cells, together with a local source of sustained IL-2, resulted in an autologous anti-leukaemic in vitro immune response.

A Functional Anti-Human 4-1BB Ligand Monoclonal Antibody that Enhances Proliferation of Monocytes by Reverse Signaling of 4-1BBL

4-1BB Ligand (4-1BBL), a transmembrane molecule, member of the tumor necrosis factor ligand superfamily, is an important costimulatory molecule in the immune response. In this study a functional anti-human 4-1BBL MAb 1F1 was obtained and the specificity of this MAb was verified by flow cytometry and Western blotting. This MAb effectively recognized the 4-1BBL molecule expressed on a series of malignant cell lines as well as on DC and monocytes and it inhibited the proliferation of T lymphocytes, costimulated by soluble 4-1BBL and agonist anti-human CD3 MAb. Furthermore, we demonstrated that MAb 1F1 induced an impressive proliferation of monocytes from peripheral blood by triggering the reverse signal through 4-1BBL. This functional anti-human 4-1BBL MAb provides a valuable tool for further study of biological functions as well as signal transduction of 4-1BBL/4-1BB.

Increasing the yield of human mononuclear cells and low serum conditions for in vitro generation of macrophages with M-CSF

The yield of mononuclear cells extracted from peripheral blood using standard protocols is frequently inadequate when working with material of limited availability. In addition, the regular usage of autologous and fetal calf serum (FCS) to generate human macrophages in vitro may complicate antigen uptake, processing and presentation on HLA molecules. We optimized the yield of mononuclear cells from 34+/-3% to 65+/-5% by collecting both the interface and more than half of the overlayering supernatant, followed by three washes at 4 degrees C. Monocytes from 12 individuals were cultured 1-4 days with 0-100 ng/ml macrophage colony-stimulating factor (M-CSF) at either 1% (low) or 5% (v/v) FCS. Regardless of number of days in culture, maximal (50-100 ng/ml) M-CSF stimulation and low FCS induced 65+/-5% esterase-positive cells in all individuals compared to 52+/-7% without M-CSF (p<0.001). M-CSF increased the mean proportion of esterase-positive cells in both 1% and 5% FCS with a negative interaction found between 5% FCS and M-CSF (p<0.05). All cells were positive for CD14 and HLA class II but cell number did not increase. The generation of human macrophages by M-CSF at low FCS should prove useful in studies where higher FCS concentrations may interfere with the assay.

Temporary changes in macrophages and MHC class-II molecule-expressing cells in the tubulointerstitium in response to uranyl acetate-induced acute renal failure in rats

The present study was designed to asses the dynamic changes in macrophages (Møs) with or without expression of major histocompatibility complex (MHC) class-II molecule in response to uranyl acetate-induced acute renal failure (ARF) in rats. ED1+ monocytes/Møs infiltrated into the interstitium as early as day 2, peaked in number on day 5 after uranyl acetate-induced ARF. ED1+ cells did not correlate with necrotic tubules but accumulated abundantly in the vicinity of the Ki67+ regenerating proximal tubules around days 4-5. Afterward, regeneration of proximal tubules was accelerated. After day 5, some ED1+ cells entered the tubular lumen, and became ED1+ giant cells, which had features of phagocytic Møs by immunoelectron microscopy, peaking in number on day 7. Most ED1+ cells did not incorporate [(3)H]-thymidine, indicating lack of active proliferation. The number of OX6+ cells (directed to MHC class-II molecule) in the interstitium significantly increased on day 4 and peaked on day 5. Double staining revealed that ED1+OX6- cells entered the tubular lumen while ED1+OX6+ cells remained in the peritubular regions. Osteopontin (OPN) protein and mRNA were significantly upregulated. No specific relationship could be found between OPN+ regenerating proximal tubules and ED1+ cells, but most ED1+ giant cells were OPN+ and intermingled among OPN+ cell debris. Our findings suggest that ED1+ Møs are actively associated with regenerating proximal tubules and, thus, might promote proximal tubular regeneration. ED1+OX6- Møs may function as scavengers and phagocytose cellular debris in the tubular lumen, cleaning the wound site. OPN might be involved in this process. ED1+OX6+ Møs in the peritubular regions may act as outpost of the defense system to monitor incoming antigens. Our data indicate that Møs with or without expressing MHC class-II molecule contribute to the defense and repair of injured proximal tubules in this ARF.

Antigen entrapped in the escheriosomes leads to the generation of CD4(+) helper and CD8(+) cytotoxic T cell response

In previous study, we demonstrated the potential of Escherichia coli (E. coli) lipid liposomes (escheriosomes) to undergo membrane-membrane fusion with cytoplasmic membrane of the target cells including professional antigen presenting cells. Our present study demonstrates that antigen encapsulated in escheriosomes could be successfully delivered simultaneously to the cytosolic as well as endosomal processing pathways of antigen presenting cells, leading to the generation of both CD4(+) T-helper and CD8(+) cytotoxic T cell response. In contrast, encapsulation of same antigen in egg phosphatidyl-choline (egg PC) liposomes, just like antigen-incomplete Freund's adjuvant (IFA) complex, has inefficient access to the cytosolic pathway of MHC I-dependent antigen presentation and failed to generate antigen-specific CD8(+) cytotoxic T cell response. However, both egg PC liposomes as well as escheriosomes-encapsulated antigen elicited strong humoral immune response in immunized animals but antibody titre was significantly higher in the group of animals immunized with escheriosomes-encapsulated antigen. These results imply usage of liposome-based adjuvant as potential candidate vaccine capable of eliciting both cell-mediated as well as humoral immune responses. Furthermore, antigen entrapped in escheriosomes stimulates antigen-specific CD4(+) T cell proliferation and also enhances the level of IL-2, IFN-gamma and IL-4 in the immunized animals.

Nitric oxide-independent CTL suppression during tumor progression: association with arginase-producing (M2) myeloid cells

Most of the mice bearing a s.c. BW-Sp3 lymphoma tumor mount a CD8(+) T cell-mediated response resulting in tumor regression. Nonetheless, tumor progression occurs in some of the recipients and is associated with CTL inactivity. We demonstrated that T cell-activating APC were induced in regressors whereas T cell suppressive myeloid cells predominated in the spleen of progressors. Indeed, in vitro depletion of either the adherent or the CD11b(+) populations restored T cell cytotoxicity and proliferation in these mice. This CTL inhibition was cell-to-cell contact-dependent but not mediated by NO. However, the same progressor suppressive cells prevented the activity of in vitro-restimulated CTLs derived from regressors in a cell-to-cell contact and NO-dependent fashion. Thus, either the NO-dependent or -independent suppressive pathway prevailed, depending on the target CTL population. In addition, the suppressive population expressed a high arginase activity, suggesting an association of the suppressive phenotype with alternatively activated (M2) myeloid cells. However, the high arginase activity is not directly involved in the suppressive process. Our results provide new insights for myeloid cell-mediated CTL inhibition during cancer progression.

Sarcoidosis susceptibility and resistance HLA-DQB1 alleles in African Americans

Sarcoidosis, in the United States, more commonly and severely affects African Americans. HLA associations with sarcoidosis have been reported, but most studies used case-control designs, which may produce biased results because of population stratification. We examined transmission of HLA-DQB1 alleles in 225 African American families with at least one offspring with sarcoidosis. Of five low-resolution HLA-DQB1 alleles, *02 and *06 showed significant deviation in transmission patterns to affected offspring. High-resolution typing of these allelic subsets revealed that HLA-DQB1*0201 was transmitted to affected offspring half as often as expected (p = 0.001), whereas DQB1*0602 was transmitted to affected offspring about 20% more often than expected (p = 0.029). Examining interactions between *0201 and *0602 alleles and environmental exposures showed that *0602 varied little with respect to exposure, but sarcoidosis risk associated with *0201 often depended on exposure status. Alternatively, the *0602 allele in affected probands was associated with radiographic disease progression, but the *0201 allele showed no significant correlation with phenotype. Major differences in the amino acid sequences encoded by *0201 and *0602 alleles exist, which may explain the differential effects these alleles have on sarcoidosis susceptibility and progression in African Americans.

M-CSF induced differentiation of myeloid precursor cells involves activation of PKC-delta and expression of Pkare

Macrophage-colony stimulating factor (M-CSF) regulates proliferation and differentiation of cells belonging to the monocytic lineage. We investigated the mechanisms of M-CSF differentiation signaling in follicular dendritic cell-P1 cells and analyzed the catalytic activation of different protein kinase C (PKC) isoforms. M-CSF induced rapid catalytic activation of PKC-delta and membrane translocation of the tyrosine phosphorylated form of PKC-delta. Mutation of tyrosine 807 in the M-CSF receptor (Fms) abrogates cell differentiation but not a proliferative response to M-CSF, and FmsY807F failed to activate PKC-delta. We also investigated the downstream signaling pathways from PKC-delta. A cyclic adenosine monophosphate-regulated Ser/Thr kinase gene, protein kinase X (PRKX), has been associated with macrophage differentiation in human cells. We found that M-CSF and PKC-delta induced the expression of the PRKX murine homologue: PKA-related gene. Taken together, our results indicate that PKC-delta functions as a critical mediator of M-CSF-induced differentiation signaling.

Avian reovirus induces an inhibitory effect on lymphoproliferation in chickens

The cellular immune responses of chickens inoculated with the vaccine strain S-1133 and/or a field isolate VA-1 of avian reovirus (ARV) were studied. Both strains of virus caused inhibition of the phytohaemagglutinin (PHA)-induced lymphoproliferative response of peripheral blood mononuclear cells (PBMC) and splenic mononuclear cells (SMC) during the initial stage from day 4 up to day 10 post-inoculation (PI), with a later return to the normal value. The inhibition in the PHA-induced lymphoproliferation of SMC could be partially overcome by depletion of adherent cells. The supernatant of the PHA-stimulated SMC culture was also checked in vitro for the presence of suppressive factor(s) produced in response to ARV infection. The culture supernatant from chickens at day 5 PI caused significant inhibition of the PHA-induced lymphoproliferation of control birds, suggesting the presence of suppressive factor(s). ARV infection also significantly inhibited IL-2 production on day 5. There was a significant increase in nitric oxide production by the splenic mononuclear cells of chickens inoculated with either strain of ARV.

Regulation of macrophage function by the antioxidant N-acetylcysteine in mouse-oxidative stress by endotoxin

Changes in several functions of peritoneal macrophages from mice with oxidative stress caused by intraperitoneal injection of endotoxin (Escherichia coli lipopolysaccharide, LPS) (100 mg/kg), and associated with a high production of reactive oxygen species (ROS), have been observed in our previous studies. Antioxidants such as N-acetylcysteine (NAC) are free radical scavengers that improve and modulate the immune response, especially in oxidative stress situations. Therefore, in the present work, we have studied the effects of the administration of NAC (150 mg/kg i.p.) on different functions of peritoneal macrophages from Swiss mice suffering that oxidative stress, caused by LPS (100 mg/kg). NAC was injected 30 min after LPS injection, and the peritoneal macrophages were obtained at 2, 4, 12, and 24 h after endotoxin injection. The following functions, key stages of the phagocytic process, were studied: adherence to substrate, chemotaxis, ingestion of particles, and production of ROS (reactive oxygen species), as well as tumor necrosis factor (TNFalpha) release. The decrease in chemotaxis and the increase in adherence, ingestion, superoxide anion production, and TNFalpha release shown by macrophages from animals with oxidative stress were counteracted by NAC injection. These data suggest that NAC administration may be useful for the treatment of oxidative stress-linked endotoxic shock, modulating the function of macrophages, specifically in decreasing the production of ROS and of inflammatory cytokines such as TNFalpha.

Primary dendritic cells phagocytose Cryptococcus neoformans via mannose receptors and Fcgamma receptor II for presentation to T lymphocytes

Different "professional" antigen-presenting cells (APC) have unique characteristics that favor or restrict presentation of microbial antigens to T cells, depending on the organism. Cryptococcus neoformans is a pathogenic yeast that presents unique challenges to APC, including its large size, its rigid cell wall, and its ability to stimulate T cells as a mitogen. T-cell proliferation in response to the C. neoformans mitogen (CnM) requires phagocytosis and processing of the organisms by accessory cells prior to presentation of CnM to T cells. Because of the requirement for uptake of the organism and more limited costimulatory requirements of mitogens, macrophages might be the most likely cellular source for the accessory cell. However, the present study demonstrates that a transiently adherent cell that was CD3(-), CD14(-), CD19(-), CD56(-), HLA-DR(+), and CD83(+) with a dendritic morphology, rather than monocyte-derived or tissue (alveolar) macrophages, was the most efficient APC for presentation of CnM. A large number of these cells bound and internalized the organism, and only a small number of dendritic cells were required for presentation of the mitogen to T cells. Further, the mannose receptor and Fcgamma receptor II were required for presentation of C. neoformans, as blocking either of these receptors abrogated both uptake of C. neoformans and lymphocyte proliferation in response to CnM. These studies demonstrate the surprising fact that dendritic cells are the most efficient accessory cells for CnM.

Endometriotic haptoglobin binds to peritoneal macrophages and alters their function in women with endometriosis

OBJECTIVE

To evaluate the effects of endometriotic haptoglobin on peritoneal macrophage function.

DESIGN

Prospective laboratory study.

SETTING

School of medicine.

PATIENT(S)

Twenty-three women with and without endometriosis.

INTERVENTION(S)

Peritoneal macrophages cultured without or with haptoglobin.

MAIN OUTCOME MEASURE(S)

Peritoneal macrophage haptoglobin immunoreactivity, adhesion, and interleukin-6 (IL-6) production.

RESULT(S)

In vivo, significantly more peritoneal macrophages from women with endometriosis bound haptoglobin and exhibited reduced adhesion compared to women without endometriosis. In vitro, haptoglobin treatment significantly decreased peritoneal macrophage adherence only in women without endometriosis; this effect was not seen in women with endometriosis, probably owing to in vivo haptoglobin saturation. Conversely, haptoglobin treatment robustly increased IL-6 production only by macrophages from women with endometriosis, suggesting differential immune response in these women.

CONCLUSION(S)

Endometriotic lesions synthesize and secrete a unique form of haptoglobin (endometriosis protein-I) that is up-regulated by IL-6. This study shows that haptoglobin adheres to peritoneal macrophages; decreases adhesion, which may influence phagocytic function; and up-regulates IL-6 production. Hence, a feed-forward loop is proposed whereby endometriotic lesion haptoglobin decreases macrophage phagocytic function while increasing IL-6 production, which in turn increases endometriotic haptoglobin and promotes establishment of endometriosis.

Chlamydia pneumoniae infections prevent the programmed cell death on THP-1 cell line

Chlamydia pneumoniae is an obligate intracellular bacterium which frequently causes airway infection in humans and has been implicated in chronic inflammatory disease and atherosclerosis. Here we show that infection with C. pneumoniae protects THP-1 cells against the apoptosis which spontaneously occurs in macrophages in the absence of an activation signal. Analysis by flow cytometry at different post-infection times revealed that 50+/-7% of THP-1 cells were apoptotic at 48 h after onset of the experiments, whereas C. pneumoniae-infected cultures (multiplicity of infection, MOI=30) displayed only 18+/-4% of cells in apoptosis. At MOI=20 and MOI=10 the cells susceptible to apoptosis at 48 h were 28+/-5% and 35+/-6% respectively. Moreover, the results show that heat-inactivated bacteria do not give significant protection against apoptosis, even at higher MOI (MOI=30), while UV-treated Chlamydia did provide a degree of protection against apoptosis. These data suggest that the anti-apoptotic effect of C. pneumoniae requires a heat-labile component released during infection, and that the effect is not lipopolysaccharide-dependent.

Activation of p38 mitogen-activated protein kinase attenuates Leishmania donovani infection in macrophages

Leishmania-induced macrophage dysfunctions have been correlated with altered signaling events. In this work, we report that SB203580, a specific inhibitor of p38 mitogen-activated protein kinases (MAPK), increases Leishmania donovani survival in human peripheral blood mononuclear macrophages. Consistent with this finding, activation of p38 and c-jun N-terminal kinase (JNK) MAPK signaling pathways by anisomycin significantly reduced parasite survival within these cells. However, the majority of the effect was seen in a 50% reduction in the percentage of macrophages infected, with little effect on the highly infected macrophages. The observed effect was likely to be due to the p38 MAPK pathway since SB203580 was able to completely reverse the effect of anisomycin. These findings suggest that the previously reported p38 MAPK inhibition by Leishmania infection may be partially overcome by anisomycin. Similar effects were observed in pretreated macrophages or in treatment of infected macrophages. These results suggests that p38 MAPK activation may have a potential therapeutic value in the treatment of visceral leishmaniasis.

Functional dichotomy of a 20-mer and 16-mer peptide derived from Staphylococcus aureus protein A: importance of amino acid sequence

Protein A (PA) of Staphylococcus aureus possesses a wide variety of biological properties such as antitumor, antitoxic, anticarcinogenic, immunomodulatory, antifungal and antiparasitic. Since PA is a foreign protein, it is quite logical to assume that it may be cleaved into smaller peptide fragments in vivo, which may be responsible for the diverse biological activities of whole PA. We have shown that two proteolytic peptide fragments (20-mer and 16-mer) of PA mimics IgG binding and some of the immunomodulatory properties of PA. In the present study, we investigated upon the functional similarity and dissimilarity in these two peptides. The 16-mer peptide induces the production of IL6, IL10, TNFalpha and IL1alpha but it does not have any effect on secretion of IFNgamma and IL4. Whereas 20-mer peptide induces production of TNFalpha, IL1alpha along with induction of IFNgamma but it downregulates IL4, IL6 and IL10 production. IFNgamma to IL4 ratio clearly indicates that the 20-mer peptide induces Th1 type response, whereas 16-mer peptide induces Th0 type response. The 20-mer peptide retains the antitumor property of the native protein (PA) in Ehrlich ascitis tumor model, whereas 16-mer peptide does retain the same property only in vitro. The 16-mer peptide however can activate macrophages to kill Ehrlich ascitis tumor cells in vitro more efficiently than that of 20-mer peptide. Thus both the peptides although derived from same native protein and has had 13 aminoacid residues in common, appears to evoke different reactivites in the immune system. Thus it appears that the IgG binding ability which is seen with the native protein A molecule and also with both 16-mer and 20-mer peptides do not automatically confer upon them the antitumor property, and cytokine producing activities. Thus it appears that all different properties associated with Protein A may not be necessarily associated with its IgG binding abilities.

Macrophages are necessary for maximal nuclear factor-kappa B activation in response to endotoxin

To define the role of macrophages in regulating the lung's response to Escherichia coli endotoxin (lipopolysaccharide [LPS]), depletion of macrophages was accomplished by administration of dichloromethylene diphosphonate (clodronate) delivered via intratracheal (i.t.) and/or intravenous (i.v.) routes. Clodronate reduced the number of macrophages in lung lavage 48 h after either i.t. or i.v. administration, but combined i.t. + i.v. clodronate achieved the most profound depletion (90%). Although i.t. clodronate alone had little effect on the evolution of lung inflammation, combined i.t. + i.v. clodronate treatment decreased neutrophilic alveolitis 4 h after exposure to aerosolized LPS by 80% compared with mice treated with empty liposomes. This decrease was associated with impaired activation of nuclear factor (NF)-kappa B and lower concentrations of tumor necrosis factor (TNF)-alpha in lung lavage fluid. Combined i.t. + i.v. clodronate markedly reduced lung NF-kappa B activation and the intensity of neutrophilic alveolitis after intraperitoneal (i.p.) LPS; however, i.v. clodronate alone had no effect on NF-kappa B activation in either liver or lung tissue or the development of neutrophilic alveolitis. We conclude that generalized macrophage depletion reduces NF-kappa B activation, generation of cytokines, and neutrophilic lung inflammation in response to gram negative bacterial endotoxin. These findings define the role of the macrophage as a critical component for initiation of the NF-kappa B-dependent innate immune response.

Deferoxamine and hespan complex as a resuscitative adjuvant in hemorrhagic shock rat model

The optimal type and amount of fluid for resuscitation of injured patients in hemorrhagic hypovolemic shock remains controversial. Use of deferoxamine, an iron chelator and oxygen-free radical scavenger, and hespan (hydroxyethyl starch), a colloid plasma expander, was evaluated in a rat hemorrhagic shock model. Eighty Sprague-Dawley male rats were utilized in four experiments. In these rats, bi-femoral cutdowns were performed for blood withdrawal, resuscitation, blood sampling, and continuous blood pressure monitoring. All rats, except control (with bilateral cutdown only), were bled and maintained at 40 mmHg for 90 min. The shed blood was returned and animals were resuscitated. One hour later, 2 mg/kg lidocaine was injected and blood samples were taken at 10, 15, 30, and 60 min for evaluation of lidocaine derivative monoethylglycinexylidide (MEGX) by fluorescent polarization immunoassay. In experiment 1 (n = 31), resuscitation with different volumes of Ringer's lactate (7.5 mL, 15.0 mL, and 30.0 mL/kg) was compared and 7.5 mL/kg LR was most beneficial. In experiment 2 (n = 22), resuscitation with three doses of Hespan (3.75 mL, 7.5 mL, and 15 mL/kg) was compared. A dose of 15 mL/kg significantly improved the liver function. In experiment 3 (n = 15), resuscitations with two doses of deferoxamine (30 mg and 100 mg/kg) were compared. A dose of 100 mg/kg significantly improved the liver function. In experiment 4 (n = 12), a combination of deferoxamine (100 mg/kg) and Hespan (3.75 and 7.5 mL) was used. Deferoxamine (100 mg/kg) complexed with 7.5 mL of Hespan was found the most beneficial resuscitation. This conjugate could be a choice as a resuscitative adjuvant in hypovolemic shock without any side effects.

A peptide derived from bovine beta-casein modulates functional properties of bone marrow-derived macrophages from germfree and human flora-associated mice

The purpose of this study was to evaluate the immunomodulatory activity of a peptide derived from bovine beta-casein (beta-CN), the beta-CN (193-209) peptide, on mouse macrophages that were obtained either from germfree (GF) or from human flora-associated (HF) mice. Macrophages were derived from bone marrow (BMDM) in the presence of recombinant macrophage colony-stimulating factor and exposed to the peptide or lipopolysaccharide (LPS). Membrane marker expression [F4/80, Mac-1, major histocompatibility complex (MHC) class II antigens] and phagocytic activity were assessed by flow cytometry. Production of tumor necrosis factor-alpha and interleukin (IL)-6 was measured by bioassays and production of IL-1alpha, IL-1beta and IL-12 by ELISA. The expression of cytokine mRNA was determined using semi-quantitative reverse transcription-polymerase chain reaction. The beta-CN (193-209) peptide up-regulated MHC class II antigen expression and phagocytic activity of BMDM from GF and HF mice. Its enhancing effect on phagocytosis was greater than that after LPS stimulation (P < 0.01). The peptide induced notable levels of cytokine mRNA in BMDM from GF and HF mice, but it was a significantly weaker inducer of cytokine secretion than LPS. Nevertheless, although flora implantation had no stimulatory influence on basal MHC class II and basal cytokine levels, cells from HF mice were more susceptible than those from GF mice to the peptide effects on these variables. These results indicate that the beta-CN (193-209) peptide could enhance antimicrobial activity of macrophages without proinflammatory effects.

Insights into the Role of Infection in the Spondyloarthropathies

Certain infections play an important role in the pathogenesis of the human leukocyte antigen (HLA)-B27-associated reactive arthritis. Whether infections play a role in other forms of spondyloarthropathies is not as clear. The role of HLA-B27 as an antigen-presenting molecule is important in the pathogenesis of these diseases. Recent evidence has been obtained indicating that this molecule may have other functions unrelated to antigen-presentation in the interaction of reactive arthritis-triggering microbes and host. This paper reviews the recent studies on the role of infection in the spondyloarthropathies.

Aryl hydrocarbon receptor/dioxin receptor in human monocytes and macrophages

Aryl hydrocarbon receptor (AhR) belongs to the bHLH/PAS transcription factor family and is activated by various polycyclic or halogenated aromatic hydrocarbons, e.g. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3-methylcholanthrene (3MC). In the present study, we showed that in U937 cells and human macrophages AhR, with its partner cofactor Arnt, is expressed and CYP1A1 mRNA expression is induced in the presence of AhR ligand 3MC. Moreover, we showed that AhR, associating with Arnt, binds to target DNA sequences and activates transcription. Since part of AhR is activated into DNA binding species in the absence of exogenous ligand and competitive AhR antagonist alpha-naphthoflavone inhibits this activation process with reducing CYP1A1 mRNA expression levels, the presence of endogenous ligand is indicated.

Ascorbic acid and N-acetylcysteine improve in vitro the function of lymphocytes from mice with endotoxin-induced oxidative stress

Oxidative stress associated with reactive oxygen species (ROS) and cytokines produced by immune cells, which is involved in septic shock caused by endotoxin, can be controlled to a certain degree by antioxidants with free radical scavenging action. N-acetylcysteine (NAC) and ascorbic acid (AA) are ROS scavengers that improve the immune response, and modulate macrophage function in mice with endotoxin-caused oxidative stress. Therefore, we have investigated the in vitro effects of these antioxidants on the functions of lymphocytes from BALB/c mice with lethal endotoxic shock caused by intraperitoneal injection of E. coli lipopolysaccharide (LPS) (100 mg/kg). Adherence to tissues and chemotaxis (the earliest two functions of lymphocytes in the immune response), as well as ROS levels and TNF alpha production were determined in the presence or absence of NAC or AA (0.001, 0.01, 0.1, 1 and 2.5 mM) in lymphocytes from peritoneum, axillary nodes, spleen and thymus obtained at several times (2, 4, 12 and 24 hours) after LPS injection. Endotoxic shock decreases the chemotaxis of lymphocytes from all the above localizations and increases their adherence, TNF alpha and ROS production. These changes in lymphocyte function were counteracted by NAC and AA, bringing these functions to values near those of control animals. Our data suggest that lymphocytes are important targets of endotoxins contributing to oxidative stress by septic shock, and that antioxidants can preserve the function of lymphocytes, preventing the homeostatic disturbances caused by endotoxin.

Use of liposomes as an immunopotentiating delivery system: in perspective of vaccine development

Liposomes have been widely used to deliver antigens to the antigen-presenting cells (APCs) and also to modify their immunological behaviour in model animals. We recently demonstrated the potential of yeast lipid liposomes to undergo membrane-membrane fusion with cytoplasmic membrane of the target cells. Interestingly, studies in the present report revealed that antigen encapsulated in yeast lipid liposomes could be successfully delivered simultaneously into the cytosolic as well as endosomal processing pathways of APCs, leading to the generation of both CD4+ T helper and CD8+ cytotoxic T cells. In contrast, encapsulation of same antigen in egg phosphatidyl-choline (PC) liposomes, just like its free form, has inefficient access to the cytosolic pathway of major histocompatibility complex (MHC) I dependent antigen presentation and failed to generate antigen specific CD8+ cytotoxic T-cell response. However, both egg PC as well as yeast lipid liposomes have elicited strong antigen specific antibody responses in immunized animals. These results imply usage of liposome encapsulated antigen as potential candidate vaccine capable of eliciting both cell mediated as well as humoral immune responses.

Differential effects of parainfluenza virus type 3 on human monocytes and dendritic cells

To understand the lack of protective immunity observed after infection with parainfluenza virus type 3 (PIV3), we tested the effect of the virus on human monocytes and monocyte-derived immature dendritic cells (DCs). Expression of viral antigens on the cell surfaces correlated with replication of the virus, which was marginal in monocytes but extremely efficient in DCs. The virus increased monocyte survival at least in part through the production of granulocyte-macrophage colony-stimulating factor but, in contrast, accelerated DC apoptosis. In addition, PIV3 infection failed to activate monocytes but induced maturation of DCs with increased expression of CD54, HLA-DR, CD86, and CD83 and production of bioactive IL-12. However, PIV3-infected DCs demonstrated low stimulatory properties in DC-T cell cocultures, a finding that could not be attributed to the production of infectious virus or IL-10. These results demonstrate for the first time that PIV3 dramatically modifies the survival and/or the function of antigen-presenting cells and might therefore prevent the development of efficient antiviral immune responses.

Malignancy: Gene Therapy Vaccines in Acute Myeloid Leukemia : A Need for Clinical Evaluation

In the last decade our understanding of the processes that govern cell growth and differentiation, malignant transformation, and metastasis has become quite sophisticated. These new insights have revolutionized our ability to diagnose and to formulate prognoses for patients with cancer, and have inspired the design and development of novel therapeutic strategies that are based on modern gene-transfer technologies and act at the gene level. Gene therapy, broadly defined as the introduction of genetic material (transgenes) into a patient's cells with an intent to confer a therapeutic benefit, represents the most direct application of recombinant DNA technology in the clinical setting. The challenging concept of modifying the genetic properties of human cells captivated very quickly the interest of clinical and molecular oncologists, and currently, numerous gene therapy clinical trials in cancer patients are under investigation worldwide. Most of these studies involve manipulating the patient's immune response to tumors. The identification of tumor-specific antigens stimulating humoral and cellular responses in cancer patients, together with a better understanding of the molecular mechanisms controlling T cell activation have dramatically accelerated the search for potent cancer vaccines. In this review, we highlight important principles of cancer immunity and cancer vaccines, we discuss critical features of genetic manipulation of tumor cells, and particularly focus on preclinical studies on gene therapy vaccines in acute myeloid leukemia (AML).

Localization and density of myeloid leucocytes in the periodontal ligament of normal rat molars

The phenotypic distribution and density of macrophage-associated antigen-expressing cells in the periodontal ligament (PDL) of normal rat mandibular first molars was evaluated by immunohistochemistry, and an attempt made to identify dendritic cells (DCs) by immunoelectron microscopy. Cells immunopositive to ED1 (a general macrophage marker) were widely distributed throughout the PDL and were most common around blood vessels. A small number of T lymphocytes and OX62 (anti-veiled cells and gammadelta T cells)-positive DC-like cells were also found. The relative density of cells immunopositive to ED9 (CD14), OX42 (CD11b), OX6 (anti-class II MHC molecules), ED2 (anti-tissue-resident macrophages), 8A2 (CD11c) and WT.1 (CD11a) varied in the mesial, distal and periapical regions of the distal root and the furcal region. This finding suggests that there are several subpopulations of ED1-positive cells which express various combinations of these markers. Immunoelectron microscopy revealed that a small, but distinct, subpopulation of ED1- and OX6-positive cells did have a DC-like ultrastructure, although the majority of these cells were identified as macrophages. The DC-like cells were characterized by poorly developed lysosomal structures and an absence of phagocytic vesicles. It was concluded that the normal rat PDL is equipped with heterogeneous populations of macrophages with regional variations in density. The DC-like cells may function as antigen-presenting cells.

Suppression of macrophage nitric oxide production by melanoma: mediation by a melanoma-derived product

The tumour-bearing state is known to induce immune dysfunction that contributes to increased infectious complications and tumour progression. However, the mechanisms underlying this immunosuppression remain unclear. This study investigated in a murine model the effects of melanoma growth on nitric oxide (NO) production by peritoneal macrophages in vivo and in vitro. B16 and K1735 melanoma cells were inoculated subcutaneously into C57BL/6 and C3H/HeN mice, respectively. Stimulated NO production by elicited peritoneal macrophages was examined in control and melanoma- bearing mice. An in vitro system was established to assess the effects of co-culturing melanoma cells (B16 and K1735) or melanoma-conditioned medium with normal peritoneal macrophages on subsequent NO production. NO production was significantly suppressed in macrophages from melanoma-bearing mice. Co-culture of normal macrophages with melanoma cells in a transwell system or with melanoma-conditioned media in vitro reproduced the defects observed in vivo without affecting macrophage viability, pointing to a melanoma-derived product as the basis for the observed suppression of NO production. This inhibition required RNA and protein synthesis and was dose and time dependent. Using inhibition profiles and neutralizing antibodies, it was demonstrated that this melanoma inhibitory activity was distinct from known NO inhibitors. Preliminary characterization attributed this activity to a melanoma-secreted protein moiety.

Immunomodulatory potential of hydrophobic analogs of Rigin and their role in providing protection against Plasmodium berghei infection in mice

Here, we report the immunomodulating potential of N-palmitoyl-amino-ethyl-rigin amide (PR) and N-cholestanyl-amino-ethyl-rigin amide (CR), the two new structural analogs of rigin (an IgG-derived tetrapeptide). Their activity profiles are compared with native tuftsin (NT) and/or N-palmitoyl-amino-ethyl-tuftsin amide (PT) taken as positive control. To explore the possibility of their use as targeting molecules, they are incorporated into the liposome bilayer and, subsequently, interacted with macrophages in an in vitro study. The new analogs of rigin with the hydrophobicity introduced at the C-terminus are found to considerably improve both the cell-mediated and the humoral immune responses in mice. However, unlike tuftsin and its analog, which mainly activate polymorphonuclear leukocytes and macrophages, the rigin analogs appear to manifest their response more through lymphocytes. When administered prophylactically to a group of mice, at the dose of 100 micrograms/0.5 ml/mouse/day for 2 days (i.v.), followed by a challenge presented with 1 x 10(6) rbcs parasitised with Plasmodium berghei on day 0, substantial reduction in parasitaemia and rate of mortality is observed. This led to increase the median survival time (MST) of the treated group in comparison to the control group. The response is found to be more prominent in CR-treated mice possibly because of the presence of steroid moiety, which is likely to have more productive interaction with cell membranes. Incorporation of these peptides into the bilayer of liposomes does not alter the permeability behavior of vesicles and, in fact, enhances their uptake by the macrophages in an in vitro study. The effect, however, is dependent on both, the concentration of peptide liposomes and the time of incubation. Present study, thus, establishes the possible use of these analogs not only as adjuvant in chemotherapy, but also as a prophylactic supplement to boost the natural immune status. The activity response of rigin analogs is manifested through lymphocytes, they can also find use in the chemotherapy of diseases, like leishmaniasis, tuberculosis and leprosy, where macrophage activity is either tamed or impaired by pathogens.