[The anti-dsDNA antibodies: validation of an original two step strategy of detection]. / Les anticorps anti-ADN natif : validation d'une stratégie originale de détection en deux temps.

Detection of anti-dsDNA antibodies is one of the major biological criteria of use in the diagnosis of systemic lupus erythematosus. Sensitivity and specificity vary greatly between existing techniques, and differ largely from one study to another. The aim of our prospective study was to evaluate a new strategy of detection comprising two steps, first, the use of a sensitive automated technique, ELISA Phadia EliA™, and second, if necessary, a more specific technique: the Crithidia luciliae immunofluorescence test (CLIFT). The latter was used in case of discrepancy with previous laboratory findings or according to the available clinical data. During the study period of 18 months, 1729 tests were requested of which 96 were finally assayed using CLIFT. Analysis of 53 discordant results showed 14 cases of lupus identified only with ELISA, and 3 only by Crithidia. In addition, 35 likely false positives of ELISA were evidenced by negative CLIFT results. These data show a clear gain in sensitivity without any loss of specificity due to the use of a second technique. Thus, this strategy was validated in our lab; it can be useful by any medical laboratory because the cost of few Crithidia luciliae slides is very low.

Human C3 deficiency associated with impairments in dendritic cell differentiation, memory B cells, and regulatory T cells.

Primary C3 deficiency, a rare autosomal inherited disease (OMIM 120700), was identified in a 2-year-old male suffering from recurrent pyogenic infections from early infancy with undetectable total complement hemolytic activity (CH50) and C3 values. The nonconsanguineous parents and the two patients' two siblings had 50% normal serum C3 concentration. The molecular abnormality associated a paternal allele coding C3 with the missense mutation p.Ser(550)Pro and an apparently null maternal allele, with production of a defective protein that could no longer be secreted. Vaccination of the child did not induce a long-term Ab response. Accordingly, switched memory IgD(-)CD27(+) B cells were barely detected, amounting to only 2.3% of peripheral blood CD19(+) cells. Cells were significantly defective in stimulating alloreactive responses. The in vitro development of immature dendritic cells and their maturation capacity were greatly impaired, with decreased CD1a expression and IL-12p70 secretion ability. These cells were unable to induce autologous B cell proliferation and Ig secretion in the presence of CD40L and C3. Finally, the regulatory T cell development ability of CD4(+) T cells after CD3 and CD46 activation in the presence of IL-2 was significantly impaired. Thus, the association of important functional defects of dendritic cells, acquisition of B cell memory, and regulatory T cells with human C3 deficiency strongly supports a major role for C3 in bridging innate and adaptive immunity in humans.

CFSE flow cytometric quantification of lymphocytic proliferation in extracorporeal photopheresis: use for quality control.

Quality control is essential to validate extracorporeal photopheresis (ECP) processes. There is just one protocol based on PHA-induced proliferation. Since it involves the use of radioactive thymidine, we developed another technique using CFSE labeling. We compared the two tests in a paired series including 18 procedures. The thymidine test was valid. Once proliferation was obtained (10 patients out of 13), the CFSE test was in close agreement with it. In particular, two cases of residual proliferation after ECP were simultaneously detected by both techniques. Only the CFSE test allows targeted analysis of lymphocytes, thus identifying a surviving lymphocytic sub-population.

[Allergenic environment in asthmatic children in Annaba (Algeria)]. / Environnement allergénique d'une population d'enfants asthmatiques à Annaba (Algérie).

We determined blood levels of total and specific immunoglobulins E in a cohort of 75 asthmatic children at Annaba (mean age: 9 years, sex ratio M/F: 1,64). Analysis clinical investigation and biological results allowed us to estimate the clinico-biological relations in this population. We showed that: atopy based on family criteria was very frequent (74%); the symptoms of atopy associated with asthma were frequent for atopic children (96%) whose majority (46%) had severe asthma (grade 3) that required treatment. Sensitization to trophallergens was rare in this population and always associated with sensitizations to pneumallergens (acariens: 2/3; cockroaches: 50%). Sensitizations to pneumallergens seemed promoted by climatic conditions in the area of Annaba that increased the risk of developing allergic diseases.

Activation state of circulating eosinophils in nasal polyposis.

BACKGROUND: Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common disease with an uncertain pathophysiology. It is characterized by polyps rich in eosinophils, with an activation status already investigated at the tissue level. In a group of CRSwNP patients, we assessed the activation status of circulating eosinophils in the blood before migration into tissues. METHODS: Thirteen patients with CRSwNP and 16 healthy volunteers were enrolled. Several biologic parameters were studied: blood count of eosinophils; plasma eosinophil cationic protein; oxidative metabolism by chemiluminescence at baseline or when activated by phorbol 12-myristate 13-acetate or platelet-activating factor, with or without interleukin-5 (IL-5); percent of granulosar cells; and mean fluorescence intensity (MFI) by flow cytometry. RESULTS: The mean number of eosinophils was significantly higher in patients with CRSwNP, whose eosinophils showed increased oxidative metabolism in the basal or activated state significantly decreasing in the presence of IL-5. There was also a higher percentage of CD49d+ , CD25+ , and CCR3+ cells in patients, and a nonsignificant decrease in descending order in MFI between the control group, patients with normal eosinophil levels, patients with hypereosinophilia, and patients with aspirin-exacerbated respiratory disease. CONCLUSION: This study demonstrates a priming state of circulating eosinophils in CRSwNP patients when compared with healthy controls, as evidenced by the extent of oxidative metabolism, with increased sensitivity to IL-5 and by the observed variations of percent and MFI of CD49d, CCR3, and CD25. This priming is thus found at the peripheral level and occurs before the migration of eosinophils to polyps, reflecting the systemic and not just local nature of abnormalities in CRSwNP.

Slight Pro-Inflammatory Immunomodulation Properties of Dendritic Cells by Gardnerella vaginalis: The "Invisible Man" of Bacterial Vaginosis?

Bacterial vaginosis (BV), the most common genital infection in reproductive-aged women, is associated with increased risk of sexually transmitted infections. Its etiology remains unclear, especially the role of Gardnerella (G.) vaginalis, an anaerobic bacterium characteristic of the BV-alteration of the vaginal ecosystem. In the genital mucosa, dendritic cells (DCs) sense bacteria of the microenvironment via receptors and then orchestrate the immune response by induction of different T cell subtypes. We investigated the interactions between G. vaginalis and human monocyte-derived DCs using a wide range of bacterial concentrations (multiplicity of infection from 0.01 to 100), and the effects of this pathogen on PHA-induced lymphocyte proliferation. As observed by electron microscopy and cytometry, G. vaginalis reduced the internalization ability of DCs by forming extracellular clusters and induced neither DC maturation, nor DC secretion of cytokines, except at the highest dose with a very early DC maturation state. The same profile was observed on lymphocytes with significant increases of proliferation and cytokine secretion only at the highest bacterial concentration. Our findings indicate that G. vaginalis possesses slight immune-stimulating activities against DCs and T cells, reflecting thus a defective inflammatory response and giving rise to the atypical, non- or low-grade, inflammatory clinical disease profile.

Is the neutrophil reactive oxygen species production measured by luminol and lucigenin chemiluminescence intra or extracellular? Comparison with DCFH-DA flow cytometry and cytochrome c reduction.

BACKGROUND: Polymorphonuclear neutrophils (PMNs) are crucial in host defense against invading microorganisms through reactive oxygen species (ROS) production. However, generated ROS released in excess into media can damage the host tissue. It is therefore essential, when exploring oxygen species production, to discriminate between its intracellular (IC) and extracellular (EC) localization. Several methods of ROS detection are commonly used. However, the literature shows that it is not always clear whether the species detected are IC or EC, especially with the chemiluminescence technique. METHODS: We compared PMN ROS production, determined by chemiluminescence, using two different probes (luminol and lucigenin) with that measured by 2'-7'-dichlorofluorescin diacetate (DCFH-DA) flow cytometry for IC production and by cytochrome c reduction for EC production. RESULTS: We found that luminol-dependent chemiluminescence explored IC ROS production more specifically (r=0.77, p<0.01: correlation between luminol-amplified chemiluminescence and DCFH-DA flow cytometry). Lucigenin-amplified chemiluminescence and cytochrome c reduction were closely related (r=0.55, p<0.01). CONCLUSION: Luminometry detection can thus afford reproducible information on intracellular ROS kinetic production using luminol and extracellular ROS detection using lucigenin, simply and at low cost.

Soluble IL-2 receptor: a biomarker for assessing myositis activity.

OBJECTIVE: To evaluate the clinical significance of serum soluble IL-2R (sIL-2R) in inflammatory myopathies. METHODS: Serum sIL-2R and CK levels were determined in 27 patients with IM during periods of disease exacerbation and inactive disease and were compared to 20 healthy controls and 23 controls with noninflammatory elevated CK. The performance of sIL-2R and CK tests for assessing disease activity was compared. RESULTS: sIL-2R levels were increased in patients with IM. Significantly higher sIL-2R levels were detected in patients with disease exacerbation than in patients with inactive disease. In patients with IM, the sIL-2R levels correlated with the CK levels. Based on ROC analysis, diagnostic accuracy of sIL-2R and CK tests for disease activity was similar. However, when the CK threshold was defined by the upper limit of the normal, the specificity for the CK test dropped to 58%. CONCLUSION: Serum sIL-2R level could be useful to distinguish disease exacerbation from damage in IM, especially in patients with persistent elevated CK levels when a clinical muscular worsening is noted. For discrimination of the disease activity, CK testing requires the use of a different threshold than the upper limit of the normal.

Dose-dependent immunomodulation of human dendritic cells by the probiotic Lactobacillus rhamnosus Lcr35.

The response of the immune system to probiotics remains controversial. Some strains modulate the cytokine production of dendritic cells (DCs) in vitro and induce a regulatory response, while others induce conversely a pro-inflammatory response. These strain-dependent effects are thought to be linked to specific interactions between bacteria and pattern recognition receptors. We investigated the effects of a well characterized probiotic strain, Lactobacillus rhamnosus Lcr35, on human monocyte-derived immature DCs, using a wide range of bacterial concentrations (multiplicity of infection, MOI, from 0.01 to 100). DNA microarray and qRT-PCR analysis showed that the probiotic induced a large-scale change in gene expression (nearly 1,700 modulated genes, with 3-fold changes), but only with high doses (MOI, 100). The upregulated genes were mainly involved in immune response and identified a molecular signature of inflammation according to the model of Torri. Flow cytometry analysis also revealed a dose-dependent maturation of the DC membrane phenotype, until DCs reached a semi-mature state, with an upregulation of the membrane expression of CD86, CD83, HLA-DR and TLR4, associated with a down-regulation of DC-SIGN, MR and CD14. Measurement of the DC-secreted cytokines showed that Lcr35 induced a strong dose-dependent increase of the pro-Th1/Th17 cytokine levels (TNFα, IL-1ß, IL-12p70, IL-12p40 and IL-23), but only a low increase in IL-10 concentration. The probiotic L. rhamnosus Lcr35 therefore induce a dose-dependent immunomodulation of human DCs leading, at high doses, to the semi-maturation of the cells and to a strong pro-inflammatory effect. These results contribute to a fuller understanding of the mechanism of action of this probiotic, and thus of its potential clinical indications in the treatment of either infectious or IgE-dependent allergic diseases.

Effects of ornithine 2-oxoglutarate on neutrophils in stressed rats: evidence for the involvement of nitric oxide and polyamines.

Diets enriched in ornithine 2-oxoglutarate (ornithine alpha-ketoglutarate; OKG) improve immune status during stress. We described previously the ability of OKG to increase the respiratory burst in polymorphonuclear neutrophils (PMNs), but the underlying mechanisms remain unclear. OKG is usually recognized as generating glutamine, arginine and polyamines. The aim of the present study was first to determine the effects of OKG on PMN bactericidal functions (chemotaxis and respiratory burst) in stressed rats, and whether these effects could be reproduced by glutamine- or arginine-enriched diets. Secondly, we investigated the metabolic pathway involved in these actions, using three metabolic inhibitors: methionine sulphoximine (an inhibitor of glutamine synthetase), S-methylthiourea (an inhibitor of inducible nitric oxide synthase) and difluoromethylornithine (an inhibitor of ornithine decarboxylase). OKG, arginine and glutamine all increased the production of reactive oxygen species (evaluated by chemiluminescence, ferricytochrome c reduction and flow cytometry). Only OKG markedly enhanced the chemotaxis index (5-fold). Inhibition of glutamine synthetase showed that glutamine production was not involved in the action of OKG. The use of S-methylthiourea and difluoromethylornithine demonstrated that OKG modulated the respiratory burst via nitric oxide (NO*) and polyamine generation. Moreover, OKG stimulated PMN migration via NO*, but arginine administration failed to reproduce this effect. These data suggest that OKG (or its metabolites) and arginine are channelled differently in PMNs. This hypothesis deserves further study.

Increased phagocytosis and production of reactive oxygen species by neutrophils during magnesium deficiency in rats and inhibition by high magnesium concentration.

Recent studies underline the importance of the immunoinflammatory processes in the pathology of Mg deficiency. Neutrophils possess a superoxide anion-generating NADPH oxidase and its inappropriate activation may result in tissue damage. The aim of the present study was to assess the effect of experimental Mg deficiency in the rat on polymorphonuclear leucocytes (PMN) activity and the role of increasing extracellular Mg. Weaning male Wistar rats were fed either a Mg-deficient or a control diet for 8 d. In Mg-deficient rats, the characteristic inflammatory response was accompanied by a marked increase in the number of PMN. Higher plasma interleukin 6 and NO concentrations and increased lipid peroxidation in the heart were found in Mg-deficient rats as compared with control rats. As shown by chemiluminescence studies, basal neutrophil activity from Mg-deficient rats was significantly elevated when compared with neutrophils from control rats. Moreover, the chemiluminescence of PMN from Mg-deficient rats was significantly higher than that of control rats following phorbol myristate acetate or opsonized zymosan activation. PMN from Mg-deficient rats also showed an increased activity of phagocytosis in comparison with neutrophils from control animals. Increasing extracellular Mg concentration in the incubating medium of PMN (0.8 v. 8.0 mM) decreased the chemiluminescence activity of PMN from control rats following opsonized zymosan activation. Chemiluminescence activities of PMN from Mg-deficient rats following phorbol myristate acetate or opsonized zymosan challenge were also decreased by high extracellular Mg concentration. From this work, it appears that PMN activation is an early consequence of Mg deficiency and that high extracellular Mg concentration inhibits free radicals generation.