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B Canque

Publications and source records attributed to B Canque.

16 recordsLinked to original sources
PubMed1999

The susceptibility to X4 and R5 human immunodeficiency virus-1 strains of dendritic cells derived in vitro from CD34(+) hematopoietic progenitor cells is primarily determined by their maturation stage.

Dendritic cells (DC) were sorted on day 8 from cultures of CD34(+) cells with stem cell factor/Flt-3 ligand/ granulocyte-macrophage colony-stimulating factor (GM-CSF)/tumor necrosis factor-alpha (TNF-alpha)/interleukin-4 (IL-4). Exposing immature CCR5(+)CXCR4(lo/-) DC to CCR5-dependent human immunodeficiency virus (HIV)-1Ba-L led to productive and cytopathic infection, whereas only low virus production occurred in CXCR4-dependent HIV-1LAI-exposed DC. PCR analysis of the DC 48 hours postinfection showed efficient entry of HIV-1Ba-L but not of HIV-1LAI. CD40 ligand- or monocyte-conditioned medium-induced maturation of HIV-1Ba-L-infected DC reduced virus production by about 1 Log, while cells became CCR5(-). However, HIV-1Ba-L-exposed mature DC harbored 15-fold more viral DNA than their immature counterparts, ruling out inhibition of virus entry. Simultaneously, CXCR4 upregulation by mature DC coincided with highly efficient entry of HIV-1LAI which, nonetheless, replicated at the same low level in mature as in immature DC. In line with these findings, coculture of HIV-1Ba-L-infected immature DC with CD3 monoclonal antibody-activated autologous CD4(+) T lymphocytes in the presence of AZT decreased virus production by the DC. Finally, whether they originated from CD1a+CD14(-) or CD1a-CD14(+) precursors, DC did not differ as regards permissivity to HIV, although CD1a+CD14(-) precursor-derived immature DC could produce higher HIV-1Ba-L amounts than their CD1a-CD14(+) counterparts. Thus, both DC permissivity to, and capacity to support replication of, HIV is primarily determined by their maturation stage.

Cell Differentiation↗
PubMed1999

Functional and phenotypic analysis of thymic CD34+CD1a- progenitor-derived dendritic cells: predominance of CD1a+ differentiation pathway.

Whether thymic dendritic cells (DC) are phenotypically and functionally distinct from the monocyte lineage DC is an important question. Human thymic progenitors differentiate into T, NK, and DC. The latter induce clonal deletion of autoreactive thymocytes and therefore might be different from their monocyte-derived counterparts. The cytokines needed for the differentiation of DC from thymic progenitors were also questioned, particularly the need for GM-CSF. We show that various cytokine combinations with or without GM-CSF generated DC from CD34+CD1a- but not from CD34+CD1a+ thymocytes. CD34+ thymic cells generated far fewer DC than their counterparts from the cord blood. The requirement for IL-7 was strict whereas GM-CSF was dispensable but nonetheless improved the yield of DC. CD14+ monocytic intermediates were not detected in these cultures unless macrophage-CSF (M-CSF) was added. Cultures in M-CSF generated CD14-CD1a+ DC precursors but also CD14+CD1a- cells. When sorted and recultured in GM-CSF, CD14+ cells down-regulated CD14 and up-regulated CD1a. TNF-alpha accelerated the differentiation of progenitors into DC and augmented MHC class II transport to the membrane, resulting in improved capacity to induce MLR. The trafficking of MHC class II molecules was studied by metabolic labeling and immunoprecipitation. MHC class II molecules were transported to the membrane in association with invariant chain isoforms in CD14+ (monocyte)-derived and in CD1a+ thymic-derived DC but not in monocytes. Thus, thymic progenitors can differentiate into DC along a preferential CD1a+ pathway but have conserved a CD14+ maturation capacity under M-CSF. Finally, CD1a+-derived thymic DC and monocyte-derived DC share very close Ag-processing machinery.

Antigens, CD↗
PubMed1998

IL-4 and CD40 ligation affect differently the differentiation, maturation, and function of human CD34+ cell-derived CD1a+CD14- and CD1a-CD14+ dendritic cell precursors in vitro.

We examined the effect of interleukin (IL)-4 or CD40 ligation on the differentiation and maturation of CD1a+CD14- and CD1a-CD14+ dendritic cell (DC) precursors. Cord blood CD34+ cells were cultured with granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor alpha (TNF-alpha), to which stem cell factor and Flt-3 ligand were added for 5 days. Phenotypic analysis of DC precursors on culture day 7 showed that CD1a+CD14- cells expressed higher CD11c and CD80 levels and lower CD116/GM-CSFR and CCR-5 levels than their CD1a-CD14+ counterparts. Culturing CD1a+CD14- precursors with GM-CSF and TNF-alpha resulted in DC with heterogeneous CD1a, HLA;SMDR (DR), CD11b, and CD83 expression, 10% of which acquired CD14. IL-4 and CD40 ligation affected their differentiation in contrasting ways: IL-4 induced CD1ahiCD14-DRloCD11b+CD83-S100+ DC with reduced MLR-stimulating capacity, whereas CD40 ligation led to CD1alo/-CD14-CD40-DRhiCD11b-CD83+S100+/- DC with stronger MLR-stimulating capacity. Also, both IL-4 and CD40 ligation promoted ReIB expression and nuclear translocation. When CD1a-CD14+ precursors were maintained in only the presence of GM-CSF and TNF-alpha, this led to mixed populations of adherent macrophages and nonadherent CD1a-CD14+ monocytes, and of CD1a+CD14- and CD1a+CD14+ DC, which were DRloCD11b+CD83-S100-. IL-4 or CD40 ligation prevented their differentiation into macrophages and resulted in DC with phenotypes close to those issued from CD1a+CD14- precursors, with only a minority staying CD14+ but most being S100-; their MLR-stimulating capacity also increased but remained lower than that of DC differentiated from CD1a+CD14- precursors. Thus, IL-4 or CD40 ligation induced CD1a+CD14- and CD1a-CD14+ DC precursors to differentiate into phenotypically close but functionally different DC populations, suggesting that DC function is primarily determined by their origin. The heterogeneity of DC should then be related to different developmental pathways and to different stages of maturation/activation.

Antigens, CD1↗
PubMed1998

Special susceptibility to apoptosis of CD1a+ dendritic cell precursors differentiating from cord blood CD34+ progenitors.

We analyzed the effect of tumor necrosis factor (TNF)-alpha on the differentiation and viability of dendritic cells (DC) generated from cord blood CD34+ progenitors cultured for five days with GM-CSF, Flt-3 ligand (FL), and stem cell factor (SCF), and then with GM-CSF only [TNF(-) cultures]. Adding TNF-alpha from the start [TNF(+) cultures] potentiated progenitor cell proliferation and promoted early differentiation of CD1a+ DC precursors without affecting differentiation of CD14+ cells, which comprise bipotent precursors of DC and macrophages, nor of CD15+ granulocytic cells. Use of TNF-alpha was associated with increased cell mortality, which peaked on culture day 10 and mainly involved CD1a+ DC. Selective apoptosis of CD1a+ DC precursors was confirmed by showing that survival of day-7-sorted CD1a+CD14- cells from TNF(+) cultures was lower than that of CD1a-CD14+ cells. That similar findings were noted for sorted CD1a+CD14- cells of TNF(-) cultures, further cultured with GM-CSF without or with TNF-alpha, indicates that apoptosis of CD1a+ DC precursors was not induced by TNF-alpha. Apoptosis of CD1a+ DC precursors occurred after the cells had lost the capacity to incorporate bromodeoxyuridin. Finally, using higher GM-CSF concentrations or adding interleukin 3 (IL-3) improved viability of CD1a+ cells. Other cytokines, such as IL-4 and transforming growth factor (TGF)-beta1, were ineffective in this respect, though they promoted differentiation of CD1a+ DC. These results indicate that TNF-alpha promotes the differentiation of CD1a+ DC precursors, which display a high susceptibility to apoptosis that can be prevented by high concentrations of GM-CSF or use of IL-3, without affecting the differentiation of the CD14+ DC precursors.

Adult↗
PubMed1998

[Dendritic cells: a complex cellular system].

Dendritic cells (DC) are the most potent antigen-presenting cells. Thus, ex vivo antigen-pulsed DC are a potentially powerful tool to induce in vivo immunity against tumor-associated or viral antigens. Therefore, culture methods to generate high numbers of DC from bone marrow or blood CD34+ hematopoietic progenitor cells have recently been developed. These methods, which use different combinations of growth factor--mainly granulocyte/macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor (TNF)-alpha and interleukin (IL)-4--make the characterization of DC obtained from CD34+ cells of different origins easier and allow to assess whether DC relate to a unique or distinct differentiation pathways. Monocytes and even macrophages can also directly differentiate into DC in the presence of GM-CSF and IL-4. This has to be reconciled with evidence supporting earlier branching off of the macrophage and DC lineages, and raises questions as to the identity of the latter lineage. Apart from DC of myeloid origin, DC may also originate from lymphoid progenitors. Because the capacity of DC to capture, process and present antigens is known to vary according to their differentiation stage, and lymphoid DC might behave differently from lymphoid DC in this respect, the definition of which type of DC to use for immunotherapy must be more precise, in order to avoid detrimental side effects or results. From a practical point of view, it is also necessary to define the most appropriate cytokine combinations and schedules thereof to optimize proliferation and differentiation of DC from different origins. These conditions should then be applied to generated DC for their efficient and safe use for clinical immunotherapy.

Cell Culture Techniques↗
PubMed1997

In vitro generation of human dendritic cells and cell therapy.

Dendritic cells (DC) are the most potent antigen-presenting cells: they, only, can prime naive T lymphocytes and even elicit generation of cytotoxic T lymphocytes to soluble antigens. Thus ex vivo antigen-pulsed DC represent a potentially powerful tool to elicit T-cell mediated responses against viral or tumor-associated antigens. Because isolation of DC as such from the blood is hampered by their scarcity, culture methods to generate them from different progenitors or precursors have been developed. Indeed, the possibility of obtaining relatively high numbers of DC from bone marrow, cord blood or adult blood CD34+ progenitors, or even blood monocytes, in cultures with different combinations of growth factors--mainly based on the use of GM-CSF, TNF-alpha and IL-4--has allowed the study of their ontogeny, the characterization of the different types of DC obtained under diverse conditions, and the assessment of whether they relate to a single pathway of differentiation. For example, the finding that monocytes and even macrophages can differentiate into DC depending on the cytokines used has to be reconciled with evidence that supports earlier branching off of the macrophage and DC lineages, and raises questions as to the identity of the latter lineage. Also, besides DC of myeloid origin, DC arise from lymphoid progenitors, and lymphoid DC display different properties than myeloid DC--at least in mice. From a practical point of view, there is a need to define the most appropriate cytokine combinations and schedules to optimize proliferation, differentiation and maturation of DC from different sources. In addition, because the capacity of DC to capture, process and present antigens varies according to their differentiation/maturation stage and origin, it appears necessary to define which type of DC to use for cell therapy in the setting of a given pathology for efficient and safe use.

Cell Differentiation↗
PubMed1996

The effect of in vitro human immunodeficiency virus infection on dendritic-cell differentiation and function.

CD1a+ dendritic cells (DC) differentiate from a major population of nonadherent CD13(hi)lin- cells that appear when human cord blood CD34+ hematopoietic progenitor cells are cultured with stem-cell factor, granulocyte/macrophage (MA) colony-stimulating factor, and tumor necrosis factor-alpha (TNF-alpha) for 5 days. CD13hilin- cells, which also comprise MA and granulocyte precursors, are CD4+ and can thus be targets of human immunodeficiency virus (HIV). Low replication was noted when these day 5 cells were infected with lymphotropic HIV-1LA1 (p24: < or = 4 ng/mL on day 8 postinfection [PI]), while high virus production occurred with MA-tropic HIV-1Ba-L, HIV-1Ada, or HIV-1-m-n. (p24: 50 to > or = 1,000 ng/mL). Strong cytopathicity (CPE) was then observed in nonadherent cells as in adherent MA. However, FACS analysis on day 7 PI showed that HIV did not affect differentiation of DC that survived CPE: apart from CD4 downmodulation related to HIV production, overall expression of CD40, CD80, and CD86 costimulatory molecules, and of HLA-DR, was unchanged relative to controls. At that time, the capacity of DC from HIV-infected cultures to stimulate the mixed leukocyte reaction was only altered less than 10-fold. Immunocytochemistry on day 7 PI showed that most HIV-infected cells were included in syncytia that were stained by anti-CD1a, anti-S100, and anti-CD14 antibodies, indicating that syncytia consisted of DC and cells of the MA lineage. Polymerase chain reaction analysis of FACS-sorted CD1a+ cells confirmed that they harbored then HIV DNA. Viral DNA was also detected in CD1a+ DC from noninfected cultures that had been exposed to HIV only after sorting. Therefore, we examined whether in infected cultures DC precursors were infected at the onset or if virus spread later from other infected cells to differentiated DC. This was answered by showing that, 24 hours postexposure to HIV, viral DNA was preferentially detected in day 5 sorted CD13hilin- versus CD13hilin- cells, and that it was found in the CD1a+ progeny of CD13(hi)lin- cells 48 hours later. In addition, HIV replication did not affect myeloid clonogenic progenitors in day 0 to day 7 PI cultures, although viral DNA was detected in colony-forming unit-granulocyte/macrophage (CFU-GM)/CFU-M colonies derived from day 3 and 7 PI cultures. Thus, precursors of DC and their progeny are susceptible to HIV in vitro, but, apart from CPE, the effect of virus production on DC differentiation or function is limited.

Antigens, CD↗
PubMed1996

Macrophage inflammatory protein-1alpha is induced by human immunodeficiency virus infection of monocyte-derived macrophages.

Disparate findings have been reported as to whether human immunodeficiency virus (HIV) affects cytokine production by macrophages (MA). We investigated production of different cytokines and of macrophage inflammatory protein (MIP)-1alpha by HIV-1Ba-L- or HIV-1Ada-infected blood-derived MA. Relative to controls, only MIP-1alpha levels increased twofold to > 10-fold in supernatants 2 to 3 weeks postinfection (PI), at the time of maximum virus production; levels of the other chemokines (RANTES, interleukin (IL)-8) and cytokines (IL-1alpha, IL-3, IL-6, granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1) investigated were not affected. MIP-1alpha mRNA signal assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) was, however, only occasionally greater in cells from infected cultures relative to controls. MIP-1alpha levels in supernatants remained in the same range as in control cultures when more than 10 mmol/L Zidovudine was added 24 hours PI, which indicates involvement of virus replication in the effect. Anti-MIP-1alpha antibody labeling identified a 10% to 25% subset of MA, strongly expressing HLA-DR and CD4, and also stained by anti-IL-6 and anti-TNF-alpha antibodies. Two weeks PI, dual staining showed that the majority of the 5% to 20% cells that were p24+ belonged to the MIP-1alpha+ population, which may define a MA subset capable to better sustain HIV replication. MIP-1alpha induced by HIV replication in MA might play a role in the pathophysiology of HIV infection; in impaired hematopoiesis; or as a CD4+ and CD8+ lymphocyte chemoattractant, by recruiting either or both HIV-susceptible and cytotoxic T lymphocytes to virus replication sites.

Antiviral Agents↗
PubMed1996

Human dendritic cell differentiation pathway from CD34+ hematopoietic precursor cells.

The most effective antigen-presenting cells for T lymphocytes are dendritic cells (DCs), the differentiation pathway of which, however, is incompletely characterized. We examined here how DCs differentiated from human cord blood CD34+ progenitor cells cultured with granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-alpha, and stem cell factor. After 5 days, 2 of 3 nonadherent cells were CD13hiHLA-DRhiCD4+, half of them were also CD14+, and < or = 10% were CD1a+. When day-5 sorted CD13hiCD1a- and CD13lo cells were further cultured, CD1a+ cells appeared in the already CD13hi population, whereas CD13hi cells, a minority of which rapidly became CD1a+, emerged from the CD13lo population. By day 12, still 66% of bulk cells in suspension were CD13hi, most of which displayed high forward and side scatters of large granular cells. Half of CD13hi cells were CD1a+. All CD13hi cells expressed to the same extent DR, CD4, costimulatory and adhesion molecules, and various amounts of CD14. CD1a+ cells stimulated allogeneic lymphocytes more than CD13hiCD1a- cells and, although they were CD14+, both cell types were nonspecific esterase-negative nonphagocytic cells and were stronger mixed leukocyte reaction stimulators than were their macrophage counterparts. Eventually, the percentage of CD1a+ cells decreased. However, typical CD1a+ DCs still emerged in culture of sorted day-12 CD13hiCD1a- cells, and adding interleukin-4 to bulk cultures at that time led to the persistence of the CD1a+ population while diminishing CD14 expression. Thus, this system results first in the differentiation of CD13hi precursors that strongly express DR and CD4, from which more mature CD1a+ DCs continuously differentiate all along the culture period.

Antigens, CD↗
PubMed1995

In vitro infection of bone marrow-adherent cells by human immunodeficiency virus type 1 (HIV-1) does not alter their ability to support hematopoiesis.

As an attempt to elucidate the pathogenesis of human immunodeficiency virus type 1 (HIV-1)-related cytopenia, the effects of infection of long-term primary bone marrow culture (LTBMC)-derived adherent cells on hematopoiesis were investigated. Productive infection could then be established only when using monocytotropic strains HIV-1Ba-L, HIV-1Ada, and HIV-1JR-FL but not with lymphocytotropic strain HIV-1LAI. Culture supernatants were tested for major cytokines involved in the regulation of hematopoiesis: neither IL-3 nor GM-CSF were detectable in the infected or noninfected cultures; in contrast, TGF-beta, TNF-alpha, MIP-1 alpha, Steel Factor, and IL-6 were detected at all times in established LTBMCs, but their levels were not consistently altered by virus replication. In vitro functional analysis by colony and long-term culture assays showed that HIV-1 infection failed to alter either the kinetics or the number of hematopoietic progenitors produced by the stromal layers; it did not interfere with the clonogenicity of exogeneous CD34+ cells in semisolid assays, and no difference was observed relative to the controls when HIV-1-infected stromal layers were tested for their ability to sustain long-term hematopoiesis. These results show that productive and sustained virus replication in the macrophage component of LTBMCs does not significantly alter the profile of major cytokines involved in regulating hematopoiesis, nor is it sufficient by itself for altering in vitro hematopoiesis under the baseline conditions used.

Bone Marrow↗
PubMed1995

Susceptibility of human bone marrow stromal cells to human immunodeficiency virus (HIV).

It is not known whether impaired hematopoiesis noted during human immunodeficiency virus (HIV) infection results from infection of stem/progenitor cells or of cells of the bone marrow microenvironment. Normal adherent primary stromal layers were exposed to HIV to determine which of this mixture of endothelial cells, fibroblasts, and macrophages are susceptible to the virus. Viral p24 in supernatants was noted with monocytotropic HIV-1Ada, HIV-1Ba-L, and HIV-1JR-FL but not with lymphotropic HIV-1LAI nor HIV-1MN strain, and only stromal macrophages expressed the viral antigens. Coculture of the layers with PHA-activated normal lymphocytes failed to rescue lymphotropic virus. No p24 was produced when macrophage-depleted stromal cells were exposed to either HIV-1Ba-L or HIV-1LAI; proviral DNA was then amplified by PCR in cells exposed to either virus, though coculture with lymphocytes rescued only HIV-1Ba-L. Altogether, these data indicate that macrophages are the major targets of HIV in cultured stromal layers. As virus replication in macrophages did not affect the profile of major cytokines involved in regulating hematopoiesis, HIV infection could alter hematopoiesis by other as yet unspecified mechanisms.

Base Sequence↗
PubMed1994

The Dielmo project: a longitudinal study of natural malaria infection and the mechanisms of protective immunity in a community living in a holoendemic area of Senegal.

The Dielmo project, initiated in 1990, consisted of long-term investigations on host-parasite relationships and the mechanisms of protective immunity in the 247 residents of a Senegalese village in which malaria is holoendemic. Anopheles gambiae s.l. and An. funestus constituted more than 98% of 11,685 anophelines collected and were present all year round. Inoculation rates of Plasmodium falciparum, P. malariae, and P. ovale averaged respectively 0.51, 0.10, and 0.04 infective bites per person per night. During a four-month period of intensive parasitologic and clinical monitoring, Plasmodium falciparum, P. malariae, and P. ovale were observed in 72.0%, 21.1% and 6.0%, respectively, of the 8,539 thick smears examined. Individual longitudinal data revealed that 98.6% of the villagers harbored trophozoites of P. falciparum at least once during the period of the study. Infections by P. malariae and P. ovale were both observed in individuals of all age groups and their cumulative prevalences reached 50.5% and 40.3%, respectively. Malaria was responsible for 162 (60.9%) of 266 febrile episodes; 159 of these attacks were due to P. falciparum, three to P. ovale, and none to P. malariae. The incidence of malaria attacks was 40 times higher in children 0-4 years of age than in adults more than 40 years old. Our findings suggest that sterile immunity and clinical protection are never fully achieved in humans continuously exposed since birth to intense transmission.

Adolescent↗
PubMed1992

[Involvement of cellular immunity in pathology. Neuromalaria].

Murin Cerebral Malaria (MCM) with Plasmodium berghei ANKA and the CBA/Ca mice is the result of an immunopathological process. An overproduction of TNF is implicated in its pathogenesis. Recent datas concerning TNF production during the course of Plasmodium vinckei vinckei infection, and analysis of relationships between MCM and Experimental Allergic Encephalomyelitis (EAE) raise the hypothesis of the involvement of an auto-immune process in the murin disease. The role of cellular immunity in human cerebral malaria remains obscure. Cytokines could majore adherence of parasitized red blood cells to cerebral endothelial cells.

Animals↗