RESUMO
Recurrent respiratory papillomatosis (RRP) is a rare, proliferative disease caused by human papillomavirus 6 (HPV6) and HPV11. RRP can occasionally spread and undergo malignant transformation. We analysed samples across time for five RRP patients with malignant transformation and four with highly recurrent, non-malignant RRP by applying high-throughput sequencing. Patients with malignant transformation were infected by HPV11_A1/A2, while most non-malignant cases were associated with HPV6. Transient multiple infections with HPV6 and HPV11 were found in two patients, and resolved later to single infections. Viral genome loads were homogeneous across groups (median=78 viral genomes per human genome). Within-patient, we did not observe differences between the viral sequences in the papillomatous lesions and in the malignant tissue. Genetic analysis of the NLRP1 gene revealed no known mutations linked to idiopathic RRP, though some novel variants merit to be explored in larger cohorts. HPV11 infections appear associated with RRP malignant transformation in young patients. Multiple infections can occur in RRP, but within-patient viral diversity is minimal for a given genotype. Our results confirm the importance of viral genotype in disease prognosis and are consistent with growing evidence of HPV11 infections to be differentially associated with RRP malignant transformation in young patients.
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The vaginal ecosystem is a key component of women's health. It also represents an ideal system for ecologists to investigate the consequence of perturbations on species diversity and emerging properties between organizational levels. Here, we study how exposure to different types of menstrual products is linked to microbial, immunological, demographic, and behavioural measurements in a cohort of young adult women who reported using more often tampons (n = 107) or menstrual cups (n = 31). We first found that cup users were older and smoked less than tampon users. When analysing health indicators, we detected potential associations between cups use reporting and fungal genital infection. A multivariate analysis confirmed that in our cohort, reporting using cups over tampons was associated with the higher odds ratio to report a fungal genital infection diagnosis by a medical doctor within the last 3 months. We did not detect significant differences between groups in terms of their bacterial vaginal microbiota composition and found marginal differences in the level of expression of 20 cytokines. However, a multivariate analysis of these biological data identified some level of clustering based on the menstrual product type preferred (cups or tampons). These results suggest that exposure to different types of menstrual products could influence menstrual health. Larger studies and studies with a more powered setting are needed to assess the robustness of these associations and identify causal mechanisms.
Assuntos
Produtos de Higiene Menstrual , Microbiota , Adulto Jovem , Feminino , Humanos , Produtos de Higiene Menstrual/efeitos adversos , Produtos de Higiene Menstrual/microbiologia , Vagina/microbiologia , Bactérias/genética , Microbiota/genéticaRESUMO
Human papillomaviruses (HPVs), the most oncogenic virus known to humans, are often associated with Herpes Simplex Virus-2 (HSV-2) infections. The involvement of the latter in cervical cancer is controversial but its long-term infections might modulate the mucosal microenvironment in a way that favors carcinogenesis. We know little about coinfections between HSV-2 and HPVs, and studying the immunological and microbiological dynamics in the early stages of these infections may help identify or rule out potential interactions. We report two cases of concomitant productive, although asymptomatic, HSV-2 and HPV infections in young women (aged 20 and 25). The women were followed up for approximately a year, with clinical visits every two months and weekly self-samples. We performed quantitative analyses of their HSV-2 and HPV viral loads, immunological responses (IgG and IgM antibodies and local cytokines expression profiles), vaginal microbiota composition, as well as demographic and behavior data. We detect interactions between virus loads, immune response, and the vaginal microbiota, which improve our understanding of HSV-2 and HPVs' coinfections and calls for further investigation with larger cohorts.
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Human papillomaviruses (HPVs) are oncogenic viruses causing most cervical cancers. Highly prevalent in young, sexually active women, only a minority of HPV infections persist. To better characterize the immuno-modulatory impact of early HPV infections, we measured changes in a panel of 20 cytokines in cervicovaginal samples collected from young women who were tested for HPV and self-reported for genital inflammation and infection symptoms. Multi-factor statistical analyses revealed that increased IL-1Alpha and IL-12/IL-23p40 concentrations were associated with HPV infection and that macrophage inflammatory proteins were associated in particular with high-risk HPV infections. ClinicalTrials.gov identifier NCT02946346.
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Alphapapillomavirus/imunologia , Infecções por Papillomavirus/imunologia , Adolescente , Adulto , Alphapapillomavirus/isolamento & purificação , Colo do Útero/imunologia , Colo do Útero/metabolismo , Colo do Útero/virologia , Feminino , Humanos , Subunidade p40 da Interleucina-12/análise , Subunidade p40 da Interleucina-12/metabolismo , Interleucina-1alfa/análise , Interleucina-1alfa/metabolismo , Estudos Longitudinais , Macrófagos/imunologia , Macrófagos/metabolismo , Infecções por Papillomavirus/sangue , Infecções por Papillomavirus/virologia , Vagina/imunologia , Vagina/metabolismo , Vagina/virologia , Adulto JovemRESUMO
Understanding genital infections by Human papillomaviruses (HPVs) remains a major public health issue, especially in countries where vaccine uptake is low. We investigate HPV prevalence and antibody status in 150 women (ages 18 to 25) in Montpellier, France. At inclusion and one month later, cervical swabs, blood samples and questionnaires (for demographics and behavioural variables) were collected. Oncogenic, non-vaccine genotypes HPV51, HPV66, HPV53, and HPV52 were the most frequently detected viral genotypes overall. Vaccination status, which was well-balanced in the cohort, showed the strongest (protective) effect against HPV infections, with an associated odds ratio for alphapapillomavirus detection of 0.45 (95% confidence interval: [0.22;0.58]). We also identified significant effects of age, number of partners, body mass index, and contraception status on HPV detection and on coinfections. Type-specific IgG serological status was also largely explained by the vaccination status. IgM seropositivity was best explained by HPV detection at inclusion only. Finally, we identify a strong significant effect of vaccination on genotype prevalence, with a striking under-representation of HPV51 in vaccinated women. Variations in HPV prevalence correlate with key demographic and behavioural variables. The cross-protective effect of the vaccine against HPV51 merits further investigation.
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Alphapapillomavirus , Infecções por Papillomavirus , Vacinas contra Papillomavirus , Neoplasias do Colo do Útero , Adolescente , Adulto , Feminino , França/epidemiologia , Genótipo , Humanos , Papillomaviridae/genética , Infecções por Papillomavirus/epidemiologia , Infecções por Papillomavirus/prevenção & controle , Prevalência , Neoplasias do Colo do Útero/epidemiologia , Neoplasias do Colo do Útero/prevenção & controle , Adulto JovemRESUMO
INTRODUCTION: Human papillomaviruses (HPVs) are responsible for one-third of all cancers caused by infections. Most HPV studies focus on chronic infections and cancers, and we know little about the early stages of the infection. Our main objective is to better understand the course and natural history of cervical HPV infections in healthy, unvaccinated and vaccinated, young women, by characterising the dynamics of various infection-related populations (virus, epithelial cells, vaginal microbiota and immune effectors). Another objective is to analyse HPV diversity within hosts, and in the study population, in relation to co-factors (lifestyle characteristics, vaccination status, vaginal microbiota, human genetics). METHODS AND ANALYSIS: The PAPCLEAR study is a single center longitudinal study following 150 women, aged 18-25 years, for up to 2 years. Visits occur every 2 or 4 months (depending on HPV status) during which several variables are measured, such as behaviours (via questionnaires), vaginal pH, HPV presence and viral load (via qPCR), local concentrations of cytokines (via MesoScale Discovery technology) and immune cells (via flow cytometry). Additional analyses are outsourced, such as titration of circulating anti-HPV antibodies, vaginal microbiota sequencing (16S and ITS1 loci) and human genotyping. To increase the statistical power of the epidemiological arm of the study, an additional 150 women are screened cross-sectionally. Finally, to maximise the resolution of the time series, participants are asked to perform weekly self-samples at home. Statistical analyses will involve classical tools in epidemiology, genomics and virus kinetics, and will be performed or coordinated by the Centre National de la Recherche Scientifique (CNRS) in Montpellier. ETHICS AND DISSEMINATION: This study has been approved by the Comité de Protection des Personnes Sud Méditerranée I (reference number 2016-A00712-49); by the Comité Consultatif sur le Traitement de l'Information en matière de Recherche dans le domaine de la Santé (reference number 16.504); by the Commission Nationale Informatique et Libertés (reference number MMS/ABD/AR1612278, decision number DR-2016-488) and by the Agence Nationale de Sécurité du Médicament et des Produits de Santé (reference 20160072000007). Results will be published in preprint servers, peer-reviewed journals and disseminated through conferences. TRIAL REGISTRATION NUMBER: NCT02946346; Pre-results.
Assuntos
Protocolos Clínicos , Doenças dos Genitais Femininos/epidemiologia , Doenças dos Genitais Femininos/virologia , Infecções por Papillomavirus/epidemiologia , Infecções por Papillomavirus/virologia , Adolescente , Estudos Transversais , Citocinas/imunologia , Feminino , França/epidemiologia , Doenças dos Genitais Femininos/imunologia , Humanos , Concentração de Íons de Hidrogênio , Estudos Longitudinais , Microbiota/imunologia , Infecções por Papillomavirus/imunologia , Inquéritos e Questionários , Vagina/virologia , Carga Viral/imunologia , Adulto JovemRESUMO
In mammalian embryonic gonads, SOX9 is required for the determination of Sertoli cells that orchestrate testis morphogenesis. To identify genetic networks directly regulated by SOX9, we combined analysis of SOX9-bound chromatin regions from murine and bovine foetal testes with sequencing of RNA samples from mouse testes lacking Sox9. We found that SOX9 controls a conserved genetic programme that involves most of the sex-determining genes. In foetal testes, SOX9 modulates both transcription and directly or indirectly sex-specific differential splicing of its target genes through binding to genomic regions with sequence motifs that are conserved among mammals and that we called 'Sertoli Cell Signature' (SCS). The SCS is characterized by a precise organization of binding motifs for the Sertoli cell reprogramming factors SOX9, GATA4 and DMRT1. As SOX9 biological role in mammalian gonads is to determine Sertoli cells, we correlated this genomic signature with the presence of SOX9 on chromatin in foetal testes, therefore equating this signature to a genomic bar code of the fate of foetal Sertoli cells. Starting from the hypothesis that nuclear factors that bind to genomic regions with SCS could functionally interact with SOX9, we identified TRIM28 as a new SOX9 partner in foetal testes.
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Regulação da Expressão Gênica no Desenvolvimento , Morfogênese/genética , Proteínas Nucleares/genética , Proteínas Repressoras/genética , Fatores de Transcrição SOX9/genética , Células de Sertoli/metabolismo , Transcriptoma , Animais , Bovinos , Cromatina/química , Cromatina/metabolismo , Embrião de Mamíferos , Feminino , Feto , Fator de Transcrição GATA4/genética , Fator de Transcrição GATA4/metabolismo , Redes Reguladoras de Genes , Masculino , Camundongos , Proteínas Nucleares/metabolismo , Ligação Proteica , Proteínas Repressoras/metabolismo , Fatores de Transcrição SOX9/metabolismo , Análise de Sequência de RNA , Células de Sertoli/citologia , Processos de Determinação Sexual , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteína 28 com Motivo TripartidoRESUMO
Inducing long-term protective memory CD8(+) T-cells is a desirable goal for vaccines against intracellular pathogens. However, the mechanisms of differentiation of CD8(+) T-cells into long-lived memory cells capable of mediating protection of immunized hosts remain incompletely understood. We have developed an experimental system using mice immunized with wild type (WT) or mutants of the intracellular bacterium Listeria monocytogenes (Lm) that either do or do not develop protective memory CD8(+) T-cells. We previously reported that mice immunized with Lm lacking functional SecA2, an auxiliary secretion system of gram-positive bacteria, did not differentiate functional memory CD8(+) T-cells that protected against a challenge infection with WT Lm. Herein we hypothesized that the p60 and NamA autolysins of Lm, which are major substrates of the SecA2 pathway, account for this phenotype. We generated Lm genetically deficient for genes encoding for the p60 and NamA proteins, ΔiapΔmurA Lm, and further characterized this mutant. Δp60ΔNamA Lm exhibited a strong filamentous phenotype, inefficiently colonized host tissues, and grew mostly outside cells. When Δp60ΔNamA Lm was made single unit, cell invasion was restored to WT levels during vaccination, yet induced memory T-cells still did not protect immunized hosts against recall infection. Recruitment of blood phagocytes and antigen-presenting cell activation was close to that of mice immunized with ΔActA Lm, which develop protective memory. However, key inflammatory factors involved in optimal T-cell programming such as IL-12 and type I IFN (IFN-I) were lacking, suggesting that cytokine signals may largely account for the observed phenotype. Thus, altogether, these results establish that p60 and NamA secreted by Lm promote primary host cell invasion, the inflammatory response and the differentiation of functional memory CD8(+) T-cells, by preventing Lm filamentation during growth and subsequent triggering of innate sensing mechanisms.
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Proteínas de Bactérias/imunologia , Proteínas de Bactérias/metabolismo , Memória Imunológica , Listeria monocytogenes/imunologia , Listeriose/imunologia , N-Acetil-Muramil-L-Alanina Amidase/imunologia , N-Acetil-Muramil-L-Alanina Amidase/metabolismo , Animais , Proteínas de Bactérias/genética , Linfócitos T CD8-Positivos/imunologia , Modelos Animais de Doenças , Deleção de Genes , Listeria monocytogenes/genética , Listeria monocytogenes/fisiologia , Listeriose/microbiologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , N-Acetil-Muramil-L-Alanina Amidase/genética , Fatores de Virulência/genética , Fatores de Virulência/imunologia , Fatores de Virulência/metabolismoRESUMO
The African pygmy mouse Mus minutoides is characterized by the presence of a high proportion of fertile XY females in natural populations. This species displays 2 morphologically different X chromosomes: the ancestral X and a shorter one designated as X*, feminizing the X*Y individuals. This strongly suggests that in the presence of an X* chromosome, the male differentiation program is not activated despite a functional Y chromosome. In this study, we compared the histology of the adult ovaries of the 3 female genotypes (XX, XX* and X*Y) and investigated the expression of some of the main genes involved in male and female differentiation. We found that X*Y gonads display a typical ovarian structure without any testicular organization. Moreover, the ovarian somatic marker FOXL2 is detected in X*Y follicle cells and exhibits the same pattern as in XX and XX* ovaries, whereas SOX9 and DMRT1 are absent at all stages of follicular differentiation. However, surprisingly, X*Y ovaries display a higher level of Sry transcripts compared to testes. Our findings confirm the complete sex reversal in X*Y individuals with no apparent sign of masculinization, providing an attractive model to unravel new gene interactions involved in the mammalian sex determination system.
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Cromossomos de Mamíferos/genética , Ovário/anatomia & histologia , Ovário/metabolismo , Processos de Determinação Sexual/genética , Cromossomo X/genética , Cromossomo Y/genética , África , Animais , Peso Corporal , Feminino , Regulação da Expressão Gênica , Masculino , Camundongos , Fenótipo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteína da Região Y Determinante do Sexo/metabolismo , Testículo/metabolismoRESUMO
All therian mammals have a similar XY/XX sex-determination system except for a dozen species. The African pygmy mouse, Mus minutoides, harbors an unconventional system in which all males are XY, and there are three types of females: the usual XX but also XX* and X*Y ones (the asterisk designates a sex-reversal mutation on the X chromosome). The long-term evolution of such a system is a paradox, because X*Y females are expected to face high reproductive costs (e.g., meiotic disruption and loss of unviable YY embryos), which should prevent invasion and maintenance of a sex-reversal mutation. Hence, mechanisms for compensating for the costs could have evolved in M. minutoides. Data gathered from our laboratory colony revealed that X*Y females do compensate and even show enhanced reproductive performance in comparison to the XX and XX*; they produce significantly more offspring due to (i) a higher probability of breeding, (ii) an earlier first litter, and (iii) a larger litter size, linked to (iv) a greater ovulation rate. These findings confirm that rare conditions are needed for an atypical sex-determination mechanism to evolve in mammals, and provide valuable insight into understanding modifications of systems with highly heteromorphic sex chromosomes.
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Evolução Molecular , Camundongos/genética , Processos de Determinação Sexual/genética , Cromossomo X/genética , Cromossomo Y/genética , Animais , Feminino , MasculinoRESUMO
The SecA2 auxiliary secretion system of Gram-positive bacteria promotes the export of virulence proteins essential for colonization of the host in the case of both Mycobacterium tuberculosis and Listeria monocytogenes, two intracellular bacteria causing diseases in humans. We and others have demonstrated that this secretion system is also linked to the onset of long-term CD8(+) T cell-mediated protective immunity in mice. In the case of L. monocytogenes, expression of SecA2 inside the cytosol of infected cells correlates with the generation of CCL3-secreting memory CD8(+) T cells that are required for protection against secondary challenge with wild-type (wt) L. monocytogenes. Since the SecA2 ATPase is well conserved among Gram-positive pathogenic bacteria, we hypothesized that SecA2 itself bears evolutionarily conserved motifs recognized by cytosolic pattern recognition receptors, leading to signaling events promoting the differentiation of CCL3(+) memory CD8(+) T cells. To test this possibility, we generated a stable L. monocytogenes chromosomal mutant that expressed a SecA2 ATPase bearing a mutated nucleotide binding site (NBS). Similarly to a SecA2 deletion mutant, the NBS mutant exhibited rough colonies, a bacterial chaining phenotype, an impaired protein secretion profile, and in vivo virulence in comparison to wt L. monocytogenes. Importantly, mice immunized with the SecA2 NBS mutant were not protected against secondary infection with wt L. monocytogenes and did not develop CCL3(+) memory CD8(+) T cells. NBS mutant and wt SecA2 proteins were expressed to comparable extents by bacteria, suggesting that SecA2 itself is unlikely to promote the induction of these cells. Rather, one or several of the SecA2 substrate proteins released inside the cytosol of infected cells may be involved.
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Adenosina Trifosfatases/fisiologia , Proteínas de Bactérias/fisiologia , Linfócitos T CD8-Positivos/imunologia , Memória Imunológica/imunologia , Listeria monocytogenes/imunologia , Listeriose/imunologia , Proteínas de Membrana Transportadoras/fisiologia , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/imunologia , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Western Blotting , Clonagem Molecular , Feminino , Citometria de Fluxo , Listeria monocytogenes/genética , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Mutagênese Sítio-Dirigida , Canais de Translocação SEC , Proteínas SecARESUMO
Carcinoembryonic antigen-related cellular adhesion molecule 1 (CEACAM1) is a cell-surface glycoprotein, belonging to the carcinoembryonic antigen family, expressed by human neutrophils, epithelial cells, activated T and NK cells. CEACAM1 is expressed as a cell-surface molecule with different isoforms or can be secreted as a soluble protein. Here, we show that keratinocytes in the outer epidermal layer of psoriatic skin express CEACAM1, unlike those in healthy skin or in cutaneous lesions of patients with atopic or nummular dermatitis. Stimulation of primary human keratinocytes or in vitro reconstituted epidermis with culture supernatants of activated psoriatic lesion-infiltrating T cells, IFN-gamma or oncostatin M, but not IL-17, induced the expression of transcripts for the CEACAM1-long and -short isoforms and cell-surface CEACAM1, whereas soluble CEACAM1 was not produced. The uppermost layers of the epidermis in psoriatic lesions also contain neutrophils, a cell type with inflammatory and antimicrobial properties. Coculture of CEACAM1-expressing keratinocytes or CHO transfectants with neutrophils delayed spontaneous apoptosis of the latter cells. These results show that cytokine-induced cell-surface expression of CEACAM1 by keratinocytes in the context of a psoriatic environment might contribute to the persistence of neutrophils and thus to ongoing inflammation and the decreased propensity for skin infection, typical for patients with psoriasis.
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Antígenos CD/metabolismo , Antígeno Carcinoembrionário/metabolismo , Moléculas de Adesão Celular/metabolismo , Queratinócitos/metabolismo , Neutrófilos/metabolismo , Psoríase/metabolismo , Pele/patologia , Animais , Feminino , Humanos , Interferon gama/metabolismo , Interleucina-17/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Oncostatina M/metabolismo , Linfócitos T/metabolismoRESUMO
Solar ultraviolet (UV) radiation has hazardous effects on human health that are, in part, associated with its immunosuppressive effects via the induction of interleukin (IL)-10 production. Although IL-10 is produced by both T helper type 2 (Th2) cells and T-regulatory type 1 (Tr1) cells, the relative contribution of either subset in UV radiation-induced immunosuppression has not been established. Here, we show that T cells isolated from non-treated allergic contact dermatitis (ACD) reactions, 48 h following nickel challenge and propagated for 7-10 days in the presence of IL-2, were mainly CD4(+) and produced IL-10, but little interferon-gamma. A single sub-erythematous solar-simulated radiation (SSR) prior to antigen challenge exposure resulted in a clinical attenuation of the intensity of ACD reactions which was associated with a significant increase in both the magnitude of IL-10 production by skin-infiltrating T cells and the frequency of IL-10-producing Tr1 cells. Skin-infiltrating T cells in SSR-exposed, as well as non-exposed, ACD reactions showed a perturbed T-cell receptor (TCR)-Vbeta repertoire, without overexpression of a particular TCR-Vbeta gene product, indicating the presence of high frequencies of nickel non-specific T cells in ACD reactions. These results show that a single sub-erythematous SSR induces immunosuppression via the cutaneous infiltration of IL-10-producing Tr1, and to a lesser extent, Th2 cells.
Assuntos
Dermatite de Contato/metabolismo , Eritema/metabolismo , Interleucina-10/biossíntese , Luz Solar , Linfócitos T/metabolismo , Raios Ultravioleta , Adulto , Linfócitos T CD4-Positivos/metabolismo , Humanos , Interferon gama/metabolismo , Pessoa de Meia-Idade , Níquel , Radiometria , Células Th2 , Fatores de TempoRESUMO
BACKGROUND: Results from a transcriptome analysis of human CD4+ T regulatory type 1 (Tr1) clones have indicated that transcripts for the integrins CD18 and CD49b are overexpressed in these cells. The aim of this study was to investigate whether the presence of T cells concomitantly expressing these molecules could be detected in asthmatic patients and represent Tr1 cells. METHODS: Expression of CD18 and CD49b was analyzed by flow cytometry on peripheral blood mononuclear cells from asthmatic patients of various severity and healthy subjects. The cytokine production profile of purified CD4+ CD18(high) CD49b+ T cells was analyzed by ELISA. The effect of glucocorticoid treatment on the expression of CD18 and CD49b was determined. RESULTS: The frequency of peripheral blood CD18(high) CD49b+ T cells was significantly elevated in severe asthmatic patients, as compared with both mild asthmatic and healthy donors, and was diminished in asthmatic patients with a controlled status of the disease. Neither short-course oral glucocorticoid treatment of asthmatic patients ex vivo, nor culture of their peripheral blood mononuclear cells with dexamethasone in vitro, increased the frequency of CD18(high) CD49b+ T cells, indicating that their presence seems to be independent from recent anti-inflammatory treatment. However, purified CD4+ CD18(high) CD49b+ T cells from these patients, in contrast to those from healthy donors, lacked the production of the immunosuppressive cytokine interleukin-10. CONCLUSION: In contrast to healthy donors, peripheral blood CD18(high) CD49b+ T cells of asthmatic patients do not fulfill the phenotypic criteria of Tr1 cells. Nevertheless, the presence of elevated numbers of peripheral blood CD18(high) CD49b+ T cells is characteristic for patients with severe and uncontrolled asthma.
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Asma/sangue , Asma/imunologia , Antígenos CD18/imunologia , Integrina alfa2/imunologia , Linfócitos T/imunologia , Adulto , Idoso , Asma/tratamento farmacológico , Antígenos CD18/biossíntese , Dexametasona/farmacologia , Feminino , Citometria de Fluxo , Volume Expiratório Forçado , Glucocorticoides/uso terapêutico , Humanos , Imunofenotipagem , Integrina alfa2/biossíntese , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/imunologia , Masculino , Pessoa de Meia-Idade , Linfócitos T/citologiaRESUMO
Functional analysis of T lymphocytes requires in vitro stimulation of these cells under experimental conditions that mimic as closely as possible physiological in vivo stimulation and that involve antigen/T cell receptor (TCR)-mediated activation. Because of the low frequency of antigen-specific T cells in human clinical samples, stimulation with a combination of anti-CD3 and anti-CD28 monoclonal antibodies (mAbs) is a preferred method. Interaction of these mAbs with their ligand results in modulation of the mAb-ligand complex from the cell surface. However, as a result of incomplete modulation, CD3/CD28 mAb complexes often remain at the cell surface, thereby precluding subsequent indirect immunofluorescence and flow cytometry analysis using mouse immunoglobulin (Ig)-specific antibodies. This is of importance in situations in which no specific fluorochrome-conjugated mAbs are available, such as in screening procedures of Ig-containing hybridoma culture supernatants. We propose here the use of CD3/CD28 mAbs, linked to magnetic beads allowing standardization of the activation conditions, optimal activation of T cells and complete modulation of antigen-antibody complexes from the cell surface.