Ex vivo desequestration of Plasmodium falciparum-infected erythrocytes from human placenta by chondroitin sulfate A

We performed ex vivo experiments with Plasmodium falciparum-infected human placentas from primi- and multigravida women from Cameroon. All women, independent of their gravida status, had anti-chondroitin sulfate A (CSA) adhesion antibodies which cross-reacted with heterologous strains, such as FCR3 and Palo-Alto(FUP)1, which were selected for CSA binding. These antibodies, directed against the surface of infected erythrocytes obtained by flushing with CSA (IRBC(CSA)), were restricted to the immunoglobulin G3 isotypes. Massive desequestration of parasites was achieved with soluble CSA but not with anti-ICAM-1 and anti-CD36 monoclonal antibodies. All of the CSA-flushed parasites were analyzed immediately by using in vitro assays of binding to Saimiri brain endothelial cells (SBEC) expressing various adhesion receptors. Parasites derived from all six placentas displayed the CSA adhesion phenotype. However, only partial inhibition of adhesion was observed in the presence of soluble CSA or when Sc1D SBEC were treated with chondroitinase ABC. These results suggest that an additional adhesive molecule of IRBC(CSA) which binds to an unidentified receptor is present in the placenta. This new phenotype was lost once the parasites adapted to in vitro culture. We observed additional differences in the CSA adhesion phenotype between placental parasites and in vitro-cultured parasites panned on endothelial cells carrying CSA. The minimum size of fractionated CSA required for a significant inhibition of placental IRBC(CSA) adhesion to Sc1D cells was 1 to 2 kDa, which contrasts with the 4-kDa size necessary to reach equivalent levels of inhibition with panned IRBC(CSA) of this phenotype. All placental IRBC(CSA) cytoadhered to Sc17 SBEC, which express only the CSA receptor. Panning of IRBC(CSA) on these cells resulted in a significant quantitative increase of IRBC cytoadhering to the CSA of Sc1D cells but did not change their capacity for adhesion to CSA on normal placenta cryosections. Our results indicate that the CSA binding phenotype is heterogeneous and that several distinct genes may encode P. falciparum-CSA ligands with distinct binding properties.     

Small interfering RNAs targeting viral structural envelope protein genes and the 5ʹ-UTR inhibit replication of bovine viral diarrhea virus in MDBK cells

Bovine viral diarrhea viruses (BVDVs) are important pathogens of cattle that occur worldwide, and for which no antiviral therapy is available. In the present study, the inhibitory effect of small interfering (si) RNAs on bovine viral diarrhea virus 1 (BVDV-1) replication in cultured bovine cells was explored. Four synthetic siRNAs were designed to target structural envelope region genes (Erns, E1, and E2) and one cocktail of siRNA was generated to target the 5?-UTR of the BVDV-1 genome. The inhibitory effects of siRNAs were assessed by determination of infectious viral titer, viral antigen and viral RNA. The siRNA cocktail and three of the synthetic siRNAs produced moderate anti-BVDV-1 effect in vitro as shown by 25%-40% reduction in BVDV-1 antigen production, 7.9-19.9-fold reduction in viral titer and 21-48-fold reduction in BVDV-1 RNA copy number. Our findings suggest that siRNA cocktail targeted at the 5?-UTR is a stronger inhibitor of BVDV-1 replication and the targets for siRNA inhibition can be extended to BVDV-1 structural envelope protein genes.     

Expression of the histidine-rich protein PfHRP1 by knob-positive Plasmodium falciparum is not sufficient for cytoadherence of infected erythrocytes.

Six culture-adapted knob-positive Plasmodium falciparum parasites, four of which were nonbinding in an in vitro cytoadherence assay, were tested for the presence of the knob-associated histidine-rich protein PfHRP1. Two knob-positive, strongly cytoadherence-positive P. falciparum strains from Aotus monkeys were also examined. All parasites expressed PfHRP1, suggesting that it plays a structural or functional role related to knobs but is not by itself sufficient for cytoadherence of P. falciparum-infected erythrocytes.     

Trypanosoma cruzi carrying a monoallelic deletion of the calreticulin (TcCRT) gene are susceptible to complement mediated killing and defective in their metacyclogenesis

Trypanosoma cruzi calreticulin (TcCRT) can hijack complement C1, mannan-binding lectin and ficolins from serum thus inhibiting the classical and lectin complement pathway activation respectively. To understand the in vivo biological functions of TcCRT in T. cruzi we generated a clonal cell line lacking one TcCRT allele (TcCRT+/-) and another clone overexpressing it (TcCRT+). Both clones were derived from the TCC T. cruzi strain. As expected, TcCRT+/- epimastigotes showed impairment on TcCRT synthesis, whereas TcCRT+ ones showed increased protein levels. In correlation to this, monoallelic mutant parasites were significantly susceptible to killing by the complement machinery. On the contrary, TcCRT+ parasites showed higher levels of resistance to killing mediate by the classical and lectin but not the alternative pathway. The involvement of surface TcCRT in depleting C1 was demonstrated through restoration of serum killing activity by addition of exogenous C1. In axenic cultures, a reduced propagation rate of TcCRT+/- parasites was observed. Moreover, TcCRT+/- parasites presented a reduced rate of differentiation in in vitro assays. As shown by down- or upregulation of TcCRT expression this gene seems to play a major role in providing T. cruzi with the ability to resist complement system.     

The effect of fetuin and other sialoglycoproteins on the in vitro penetration of Trypanosoma cruzi trypomastigotes into fibroblastic cells

Heat-inactivated calf-, human-, and especially fetal calf serum stimulate infection of Vero cells by cell culture-derived trypomastigotes of Trypanosoma cruzi: the stimulatory effect is more marked with extracellular activated parasites or trypsinized trypomastigotes than with recently released parasites. The augmented invasion is not the consequence of a stimulation of attachment of trypomastigotes to host cells. Various sialoglycoproteins like fetuin, transferrin, fibrinogen, alpha-1-antitrypsin, mucin and goat-IgG are also effective in enhancing in vitro infectivity. Colominic acid also stimulates invasion, but other non-sialic polyanionic compounds are either ineffective (chondroitin sulfate, poly-aspartic acid) or inhibitory (heparin, phytic acid, myo-inositol hexasulfate). Fetuin, the best stimulatory compound tested, gives half-maximal activation with approximately 0.03 mg ml-1, and total activation with 0.5-1 mg ml-1. The enhancement of infectivity is time-dependent (2-3 h for maximal activation) at 37 degrees C and does not occur at 0 degrees C. Desialidated-fetuin or -fetal calf serum do not stimulate infectivity at all. Treatment with fetuin of parasites alone (or Vero cells alone), followed by removal of free fetuin and by interaction with untreated Vero cells (or parasites) indicates that the stimulation effect of fetuin occurs mainly on the trypomastigotes. No specific binding of [125I]fetuin to the parasites could be demonstrated, and incubation with exogenous neuraminidase of trypomastigotes previously activated by fetuin, reverses nearly completely the stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation and establishment in in vitro culture of a Theileria annulata– infected cell line from Spain

The isolation of Theileria annulata-infected lymphocytes using blood from an animal suffering from Mediterranean theileriosis as a source of parasites is described. The present work reports the first isolation and establishment in in vitro culture of a T. annulata-infected cell line from southwestern Europe, where Mediterranean theileriosis causes important economic losses, especially in southern Spain. The parasite was identified by staining of cells from culture with Giemsa, by immunofluorescent antibody techniques (IFAT), and by isoenzyme characterization. The possibility of using this T. annulata-infected lymphoblastoid cell line to obtain an antigen for diagnosis of Mediterranean theileriosis by IFAT and to develop a tissue-culture vaccine against this disease in our geographic area shows the significance of this isolation and culture. Received: 21 September 1996 / Accepted: 1 October 1996     

Dependence of Giardia lamblia encystation on novel transglutaminase activity

Earlier, we found that three protein disulfide isomerases (PDI) from Giardia lamblia (gPDI) also have transglutaminase (TGase) activity in vitro. We now show that differentiating Giardia cells contain isopeptide bonds (epsilon(gamma-glutamyl)lysine), the biological product of TGase activity that results in irreversible crosslinking of proteins in vivo. HPLC analyses showed the highest isopeptide bond content in cells encysting for 21 h, indicating an important role for TGase early in encystation. We were not able to detect isopeptide bonds in water-resistant cysts, possibly because they could not be extracted. One of the hallmarks of early encystation is the formation of encystation secretory vesicles (ESV) that transport nascent cyst wall proteins (CWPs) to the outer cell surface. ImmunoEM and live-cell immunofluorescence assays of encysting parasites revealed that gPDIs 1-3 are located in ESV and that gPDI-2 is also novel in that it is localized on the cell surface. Cystamine, a widely used TGase inhibitor, caused a dose-dependent inhibition of ESV formation by 21 h, thereby preventing development of trophozoites into cysts. Since cystamine (0.5-1 mM) inhibited the TGase activity of recombinant gPDIs 1-3 in vitro, PDIs appear to be the physiologic targets of cystamine. We found that when parasites were treated with cystamine, CWPs were not processed normally. These data suggest that TGase-catalyzed reactions may be needed for either the machinery that processes CWP precursors or their recruitment to ESV.     

The domain order of mammalian capping enzyme can be inverted and baculovirus phosphatase can function in cap formation in vivo

The bifunctional mammalian mRNA capping enzyme (Mce1) consists of an N-terminal triphosphatase domain Mce1(1-210) fused to a C-terminal guanylyltransferase domain Mce1(211-597). The physical domain order H(2)N-triphosphatase-guanylyltransferase-COOH mimics the temporal order of the capping reactions. To determine if the physical domain order is functionally important in vivo, we engineered an "inverted" mammalian capping enzyme InvMce1 [H(2)N-Mce1(211-597)-(1-210)-COOH]. We found that InvMce1 complemented the growth of Saccharomyces cerevisiae cet1delta and ceg1delta strains in which the endogenous yeast triphosphatase and guanylyltransferase genes were deleted. By testing truncated versions of InvMce1, we determined that Mce1(1-178) comprises a minimal functional triphosphatase domain. Baculovirus phosphatase (BVP) is a monofunctional single-domain protein with RNA triphosphatase and RNA diphosphatase activities and an undefined role in viral RNA metabolism. Here we demonstrated that BVP can function as an RNA triphosphatase for cap formation in vivo when fused to the C-terminus of Mce1(211-597). By characterizing a series of InvMce1-BVP derivatives with amino acid substitutions in the phosphate-binding loop of BVP, we showed that the in vivo activity of the mutant chimeras in cap formation is contingent upon in vitro phosphohydrolase activity of the respective BVP proteins. BVP catalysis in vitro was not limited to 5'-phosphorylated RNA or nucleotide substrates, but also embraced tripolyphosphatase and pyrophosphatase activities. BVP-specific activities with nucleotide and inorganic substrates were as follows: ATP (14 min(-1)), ADP (31 min(-1)), PPP(i) (3.7 min(-1)), and PP(i) (1 min(-1)). BVP did not hydrolyze AMP. We surmise that BVP has adapted the cysteinyl phosphatase fold to the hydrolysis of phosphoanhydrides.     

Collagen antibody-induced arthritis in mice: Development of a new arthritogenic 5-clone cocktail of monoclonal anti-type II collagen antibodies

A cocktail of 4 monoclonal anti-type II collagen antibodies recognizing conserved epitopes located within the CB11 fragment (CII 124-402) of type II collagen is currently used as an arthritogenic antibody preparation for inducing collagen antibody induced arthritis (CAIA). In order to increase the arthritogenicity of this cocktail, we have developed 7 new monoclonal antibodies to anti-type II collagen from spleen cells of DBA/1J mice immunized with bovine type II collagen, and tested for their additional effect on the arthritogenicity over that of the current 4-clone cocktail. Three of the clones (CII-3, -5 and -6) bind to the LyC1 (CII 124-290) peptide of CB11 and 1 (CII-7) of the clones binds to CB9.7 (CII 898-1020), and highly cross-reacted with other species of type II collagen. This indicates that these clones recognize conserved epitopes within type II collagen, including mouse type II collagen. On the other hand, 2 other clones (CII-1 and -4) directed against CB9.7 and 1 clone (CII-2) against CB8 (CII 403-551) were less reactive with other species of type II collagen.The arthritogenicity of the current 4-clone cocktail was significantly increased by addition of a fifth clone, CII-3. No effects were observed with other clones. The arthritogenicity of this new 5-clone cocktail was 2-fold greater than the current 4-clone cocktail in all strains of mice tested: the CIA-responder strain DBA/1J, the CIA-resistant BALB/c (H-2^d), the T-cell deficient C.B-17/l scid/scid and the CAIA-low responder C57BL/6 (H-2^b) strain. These results clearly indicated the importance of epitope specificity of arthritogenicity of autoantibodies to type II collagen. Due to its enhanced arthritogenicity, this 5-clone cocktail is capable of inducing a more consistent and severe arthritis with lower doses compared to the current 4-clone cocktail, and will provide an effective new reagent for inducing arthritis in various strains of CAIA low responder mice.     

A rapid method for separating tumour infiltrating cells and tumour cells from colorectal tumours.

As solid tumours are composed of a heterogeneous mixture of cells the role of any particular cell type is difficult to analyse. A rapid method of sorting freshly disaggregated highly viable single cell suspensions of colorectal tumours has therefore been developed. Infiltrating cells were initially sorted from tumour cell suspensions using magnetic beads coated with a cocktail of monoclonal antibodies recognising leucocyte common antigen, CD45 (lymphocytes), CDw14 (macrophages and granulocytes) and Thy-1 antigen (stromal cells). Between 4-10 x 10(6) cells, 70-87% pure, were rapidly sorted. The tumour cells were then sorted from the remaining cell suspension using a cocktail of monoclonal antibodies which recognise 100% of colorectal tumours. Between 2-7 x 10(6) tumour cells, 70-87% pure, were rapidly sorted. Both populations of cells were 95% viable and able to grow in vitro.     

Development of an Effective Method for Dendritic Cell Immunotherapy of Mouse Melanoma

Dendritic cell (DC) immunotherapy is a strong candidate for the treatment of incurable cancers especially malignant melanoma. Nevertheless, the proper guideline of DC immunotherapy does not exist. The absence of the guideline is also an obstacle to clinical trials of DC immunotherapy. So we conducted this study in order to develop an effective DC preparation method for immunotherapy in mouse malignant melanoma. Mouse bone marrow-derived DC were stimulated with tumour antigen alone or tumour antigen plus a cocktail (anti-CD40 antibody +TNF-α+ IL-1β) for 8, 24 or 48 h and the characteristics of these DC, such as surface molecules (CD40, CD80, CD86, MHC class II, CCR7), cytokines(IL-12, IFN-γ, and IL-10), DC-induced T cell proliferation in vitro , and the production of IFN-γ by those cells, were evaluated. Mice with melanoma were then treated with DC stimulated with tumour antigen alone and tumour antigen plus cocktail for 8 or 48 h. The tumour size and survival rate of these mice were then evaluated. (1) Beneficial clinical effects such as a reduction of tumour size and an increased survival rate were best observed in the group treated with DC stimulated for 8 h with tumour antigen plus cocktail. (2) The single prominent characteristic of DC stimulated for 8 h with tumour antigen plus cocktail was an elevated IL-12 secretion. The cytokine IL-12 was not secreted by other DC. Consequently, proper production of IL-12 was found to be an important requirement for DC used in immunotherapy of mouse melanoma.     

Transfected Plasmodium knowlesi produces bioactive host gamma interferon: a new perspective for modulating immune responses to malaria parasites

Transgenic pathogenic microorganisms expressing host cytokines such as gamma interferon (IFN-gamma) have been shown to manipulate host-pathogen interaction, leading to immunomodulation and enhanced protection. Expression of host cytokines in malaria parasites offers the opportunity to investigate the potential of an immunomodulatory approach by generating immunopotentiated parasites. Using the primate malaria parasite Plasmodium knowlesi, we explored the conditions for expressing host cytokines in malaria parasites. P. knowlesi parasites transfected with DNA constructs for expressing rhesus monkey (Macaca mulatta) IFN-gamma under the control of the heterologous P. berghei apical membrane antigen 1 promoter, produced bioactive IFN-gamma in a developmentally regulated manner. IFN-gamma expression had no marked effect on in vitro parasite development. Bioactivity of the parasite-produced IFN-gamma was shown through inhibition of virus cytopathic effect and confirmed by using M. mulatta peripheral blood cells in vitro. These data indicate for the first time that it is feasible to generate malaria parasites expressing bioactive host immunomodulatory cytokines. Furthermore, cytokine-expressing malaria parasites offer the opportunity to analyze cytokine-mediated modulation of malaria during the blood and liver stages of the infection.     

TRAF6在人PBMC来源的树突状细胞成熟中的作用

目的: 探讨肿瘤坏死因子受体相关因子6(TRAF6)在不同成熟度树突状细胞(DCs)中的表达及其对DCs免疫刺激活性的影响。方法: 重组人粒细胞-巨噬细胞集落刺激因子(rhGM-CSF)和重组人白细胞介素4(IL-4)体外诱导的人外周血单个核细胞来源的DCs,经TNF-α、LPS和细胞因子鸡尾酒法诱导成熟,分别以流式细胞术、ELISA和混合淋巴细胞反应(MLR)检测DCs的表面标志、IL-12分泌和刺激淋巴细胞增殖能力。Western blotting和real-time PCR分别检测各组TRAF6蛋白水平及mRNA的表达。结果: 各组DCs均表达TRAF6,成熟状态最佳的鸡尾酒诱导下DCs的TRAF6蛋白表达最高。高表达TRAF6的DCs可促进IL-12的分泌,增强刺激淋巴细胞增殖的能力。结论: TRAF6是调节DCs激活和成熟的关键因素。     

Leishmania-derived murine monocyte chemoattractant protein 1 enhances the recruitment of a restrictive population of CC chemokine receptor 2-positive macrophages

Transgenic Leishmania parasites that encode the murine chemokine monocyte chemoattractant protein 1 (MCP-1) were generated. These parasites transcribed MCP-1 mRNA and secreted MCP-1 protein. Infection of BALB/c, C57BL/6, or MCP-1 knockout (KO) mice with these parasites resulted in minimal lesion development with fewer parasites in the infected foot, lymph node, and spleen compared to wild-type-infected mice. In contrast, transgenic parasites caused substantial lesions with relatively high numbers of parasites in CC chemokine receptor 2 (CCR2) KO mice, indicating that the parasites are viable and healthy and that the lack of lesion development is CCR2 dependent. Prior infection of mice with transgenic parasites offered no protection to subsequent wild-type L. major challenge, suggesting that the transgenic parasites are controlled by an early innate immune response. Consistent with innate immunity, flow cytometry of cells from the ears of mice infected with transgenic parasites revealed an increase in the number of CCR2-positive macrophages by day 7 postinfection. The enumeration of transgenic parasites in ear lesions demonstrated a significant reduction in parasite numbers, which coincided with the increased CCR2-positive macrophage migration. CCR2-positive macrophages isolated from ears of mice infected with transgenic parasites contained virtually no parasites. In vitro studies revealed that optimal parasite killing required the recruitment of CCR2-positive macrophages, followed by stimulation with a combination of both MCP-1 and gamma interferon (IFN-gamma). This work suggests that the parasite-derived MCP-1 can recruit a restrictive population of CCR2-positive macrophages into lesions that can be optimally stimulated by MCP-1 and IFN-gamma to efficiently kill Leishmania parasites.     

一种高选择性、高效的牛视网膜微血管内皮细胞培养方法

目的建立一种高效、可行、特异性高的牛视网膜微血管内皮细胞（BREC）培养方法。方法取新鲜牛眼,分离视网膜并用DMEM进行冲洗、匀浆剪碎,过75μm筛,将滤网上滤渣转移至50ml离心管,用Ⅰ型胶原酶、DNaseⅠ及蛋白酶等多种酶混合液消化20min,人血清中和后,过46μm网筛并冲洗,离心5min,将组织扣在培养皿中,转入15ml离心管,用10%人血清含生长因子ECGS的DMEM培养液培养于25cm2,选择性培养视网膜血管内皮细胞,接种于明胶包被培养瓶中,采用ECGS配合肝素培养液促进内皮细胞生长,观察细胞形状生长特性,并用免疫化学荧光方法进行鉴定。结果选择性培养视网膜微血管内皮细胞成单层、镶嵌铺路石状生长,Ⅷ因子相关抗原免疫荧光检测为阳性纯度均大于95%以上,将细胞种在凝固的基质胶表面,12～18h形成官腔结构。结论本方法过程简单、可靠,培养的内皮细胞纯度高,生长状态良好,稳定传代,为视网膜血管生成疾病研究建立了模型。     

A method for the dispersal and characterization of leukocytes from the human female reproductive tract

PROBLEM: The isolation of human female reproductive tract (RT) cells that maintain viability and are representative of the entire population is essential for a thorough evaluation of mucosal immunity in the reproductive tract mucosa. Here, we describe the isolation of RT cells in high yields and with high viability from the Fallopian tube, uterine endometrium, endocervix, ectocervix and vagina. METHOD OF STUDY: This cell dispersion method uses an enzyme cocktail composed of pancreatin, hyaluronidase, and collagenase (PHC), and employs a 250-microm mesh screen to facilitate cell dispersion. RESULTS: The yields of cells isolated per gram of tissue in the presence of this PHC cocktail were compared and found to be strikingly higher relative to the yields obtained with other enzyme cocktails or in the absence of enzymes. Flow cytometry was used to characterize leukocyte subsets isolated from uterine endometrium in the presence of the various enzyme cocktails. The common leukocyte antigen marker CD45, pan T-cell marker CD3, monocyte/macrophage marker CD14 and B-cell marker CD19 were retained after exposure to the PHC cocktail of enzymes. The expression of CD8 and CD4 was lost after exposure to added enzymes but regained after culture overnight. CONCLUSION: These studies demonstrate the feasibility of using enzymatic digestion for the isolation of whole populations of Fallopian tube, endometrial, cervical and vaginal cells, including leukocyte subsets in high yields, and provide a foundation for investigating mucosal immune cell function in the human female RT.     

In vitro inhibition of Plasmodium falciparum by pyrazofurin, an inhibitor of pyrimidine biosynthesis de novo

The effect of pyrazofurin, an inhibitor of UMP synthesis, on Plasmodium falciparum growth in vitro has been studied. ID50 values (concentration of compound causing 50% inhibition of [3H]hypoxanthine incorporation) for the FCQ-27, FCI-1 and K-1 (chloroquine-resistant) isolates were 10 +/- 8.7, 6.4 +/- 5.3 and 6.3 +/- 0.5 microM, respectively. Comparative ID50 values for chloroquine were 13.5 +/- 4.2, 22.8 +/- 7.6 and 343 +/- 114 microM, respectively. Over the 48-h intraerythrocytic cycle of tightly synchronized parasites, pyrazofurin both reduced the parasitemia and retarded the maturation of trophozoites and schizonts. Addition of uracil or uridine to the in vitro culture did not decrease the anti-parasitic activity of pyrazofurin. Chloroquine reduced the parasitemia, but did not retard development of the remaining viable parasites. Pyrazofurin (20 microM) caused a 50% inhibition of parasite orotate phosphoribosyltransferase (E.C. 2.4.2.10) and, in the presence of adenosine kinase and ATP, a 73% inhibition of orotidine-5'-phosphate decarboxylase (E.C. 4.1.1.23).     

Evaluation of the schistosomicidal activity of the steroidal alkaloids from Solanum lycocarpum fruits

Solanum lycocarpum (Solanaceae), a Brazilian medicinal plant known as "wolf fruit," contains about 1.5% of glycoalkaloids in its dried fruits, consisting mainly of solamargine and solasonine. The present work reports the obtainment of the alkaloidic extract of the S. lycocarpum fruit by acid-base extraction and the isolation of the major alkaloid heterosides by chromatographic means, as well as the evaluation of their in vitro schistosomicidal activities. The in vitro schistosomicidal activities of the alkaloidic extract of S. lycocarpum fruits and its isolated steroidal alkaloids were undertaken against adult worms of Schistosoma mansoni. The alkaloidic extract (20, 32, and 50 μg mL(-1)), solasonine (50 μM), solamargine (32 and 50 μM), and equimolar mixture of glycoalkaloids (20, 32, and 50 μM) lead to the separation of all couple worms and extensive disruption on their teguments, such as sloughing, as well as their deaths within 24 h of incubation. In addition, the alkaloidic extract (10 and 15 μg mL(-1)), solasonine (50 μM), solamargine (10, 15, and 20 μM), and equimolar mixtures of glycoalkaloids (10 and 15 μM) reduced the development of eggs produced by the adult worms. Solamargine, containing the sugar chain moiety chacotriose, was more active than the solasonine, which contains solatriose sugar chain moiety. A synergistic effect was also observed for a mixture of solamargine and solasonine. Therefore, the alkaloidic extract of S. lycocarpum, and its major components, solamargine and solasonine, showed promising schistosomicidal activity.     

Activated T cells induce macrophages to produce NO and control Leishmania major in the absence of tumor necrosis factor receptor p55

The ability to activate macrophages in vitro for nitric oxide production and killing of Leishmania major parasites is dependent on tumor necrosis factor, although L. major-infected mice lacking the TNF receptor p55 (TNFRp55(-/-) mice) or both the TNFRp55 and TNFRp75 (TNFRp55p75(-/-) mice) are able to produce NO in vivo and eliminate the parasites. Here we report that activated T cells cocultured with macrophages results in TNFR-independent activation sufficient to control parasites and that both CD40/CD40L and LFA-1 contribute to T-cell-mediated macrophage activation. Thus, anti-CD3-stimulated T cells activated TNFR-deficient macrophages, while T cells from CD40L(-/-) mice were partially defective in triggering NO production by TNFRp55p75(-/-) macrophages. Moreover, in the presence of gamma interferon, anti-CD40 monoclonal antibody (MAb) activated TNFR-deficient macrophages. Finally, MAb blockade of LFA-1 completely inhibited macrophage NO production. Our data indicate that T cells can activate macrophages in the absence of TNF, thus providing a mechanism for how TNFR-deficient mice can control intracellular pathogens.