Biomedical subjects

J Pestel

Publications and source records attributed to J Pestel.

At least 19 recordsLinked to original sources

PubMed2005

Recombinant Mycobacterium bovis BCG producing IL-18 reduces IL-5 production and bronchoalveolar eosinophilia induced by an allergic reaction.

BACKGROUND: Allergic reactions occur through the exacerbated induction of a Th2 cell type expression profile and can be prevented by agents favoring a Th1 profile. Bacillus Calmette-Guérin (BCG) is able to induce high IFN-gamma levels and has been shown to decrease experimentally induced allergy. The induction of IFN-gamma is mediated by interleukin (IL)-12 known to be secreted upon mycobacterial infections and can be enhanced by IL-18 acting in synergy with IL-12. OBJECTIVE: We evaluated the ability of a recombinant BCG strain producing IL-18 (rBCG) to modify the Th2 type responses in a murine model of ovalbumin (OVA)-dependent allergic reaction. METHODS: Mice were injected intraperitoneally or intranasally with OVA at days 0 and 15 and exposed to an OVA aerosol challenge at days 29, 30, 31 and 34. At days 0 and 15, two additional groups of mice received OVA together with 5 x 10(6) colony forming units of either rBCG or nonrecombinant BCG. RESULTS: A time-course analysis of OVA-specific immunoglobulin (Ig)E, IgG1 and IgG2a levels indicated no significant difference between the three groups of mice. However, following in vitro stimulation with OVA, lymph node cells from rBCG-treated mice produced less IL-5 and more IFN-gamma than those of mice injected with nonrecombinant BCG. In addition, 48 h after the last OVA challenge, a strong reduction of bronchoalveolar eosinophilia was found in the rBCG-injected mice compared to the nontreated or nonrecombinant BCG-treated groups. CONCLUSION: These results indicate that the production of IL-18 by rBCG may enhance the immunomodulatory properties of BCG that suppress pulmonary Th2 responses and, in particular, decrease airway eosinophilia.

Animals↗

PubMed2004

[Involvement of dendritic cells in allergic airway diseases].

INTRODUCTION: Dendritic cells (DCs) are able to present antigen to T lymphocytes and to orientate the immune response towards a Th1 or a Th2 type. STATE OF THE ART: The aim of this report is to present different studies comparing DCs from allergic patients with those from healthy subjects using in vivo and in vitro experimental conditions. These studies have demonstrated that cellules dentritiquess from house dust mite allergic patients:i) take up house dust mite allergen more efficiently, ii) after stimulation by house dust mite allergen, secrete a restricted panel of cytokines and chemokines, and express characteristic co-stimulatory molecules, favoring a Th2 profile, iii) after stimulation by house dust mite allergen, induce Th2 cytokines secretion by T lymphocytes, and iv) favor an allergen-specific Th2 airway inflammatory response in an in vivo model of humanized mice. PERSPECTIVES: Functional modulation of DC could be a new therapeutic concept in allergic airway diseases. CONCLUSIONS: These results show phenotypic and functional specificities of DC from house dust mite allergic patients, and suggest a key-role for cellules dentritiques in the pathogenesis of allergen-dependent airway inflammatory response.

Dendritic Cells↗

PubMed2001

Histamine polarizes human dendritic cells into Th2 cell-promoting effector dendritic cells.

Allergic disorders are characterized by allergen-specific Th2-biased responses. Signals controlling Th2 cell polarization, especially those acting by polarizing dendritic cells (DC) into Th2-promoting DC (DC2), are not well known. Histamine, a mediator released by allergen-stimulated mast cells from allergic subjects, has been reported to activate human immature DC. We have therefore tested whether histamine affects DC polarization. We report here that histamine inhibits LPS-induced IL-12 production and polarizes uncommitted maturing DC into effector DC2. DC matured in the presence of histamine fail to produce IL-12 upon subsequent stimulation and prime Th2 responses, even in presence of IFN-gamma, a potent DC1-driving factor. All these effects are mediated through both H1 and H2 receptors. These data show that histamine is a potent DC2-polarizing factor and provide evidence for a novel mechanism that explains the initiation and maintenance of a predominant Th2 response in allergic disorders.

Cell Differentiation↗

PubMed2001

Human endothelial-cell specific molecule-1 binds directly to the integrin CD11a/CD18 (LFA-1) and blocks binding to intercellular adhesion molecule-1.

ICAMs are ligands for LFA-1, a major integrin of mononuclear cells involved in the immune and inflammatory processes. We previously showed that endothelial cell specific molecule-1 (ESM-1) is a proteoglycan secreted by endothelial cells under the control of inflammatory cytokines. Here, we demonstrate that ESM-1 binds directly to LFA-1 onto the cell surface of human blood lymphocytes, monocytes, and Jurkat cells. The binding of ESM-1 was equally dependent on Ca(2+), Mg(2+), or Mn(2+) divalent ions, which are specific, saturable, and sensitive to temperature. An anti-CD11a mAb or PMA induced a transient increase in binding, peaking 5 min after activation. Direct binding of ESM-1 to LFA-1 integrin was demonstrated by specific coimmunoprecipitation by CD11a and CD18 mAbs. A cell-free system using a Biacore biosensor confirmed that ESM-1 and LFA-1 dynamically interacted in real time with high affinity (K(d) = 18.7 nM). ESM-1 consistently inhibited the specific binding of soluble ICAM-1 to Jurkat cells in a dose-dependent manner. These results suggest that ESM-1 and ICAM-1 interact with LFA-1 on binding sites very close to but distinct from the I domain of CD11a. Through this mechanism, ESM-1 could be implicated in the regulation of the LFA-1/ICAM-1 pathway and may therefore influence both the recruitment of circulating lymphocytes to inflammatory sites and LFA-1-dependent leukocyte adhesion and activation.

Biosensing Techniques↗

PubMed2001

Th2 polarization by Der p 1--pulsed monocyte-derived dendritic cells is due to the allergic status of the donors.

The polarization of the immune response toward a Th2 or a Th1 profile can be mediated by dendritic cells (DCs) following antigen presentation and interaction with T cells. Costimulatory molecules such as CD80 and CD86 expressed by DCs, the polarizing cytokine environment during DC--T-cell interaction, and also the nature of the antigen are critical in the orientation of the immune response. In this study, the effect of the cysteine protease Der p 1, one of the major allergens of the house dust mite Dermatophagoides pteronyssinus, on these different parameters was evaluated comparatively on monocyte-derived DCs obtained from healthy donors, from pollen-sensitive patients, or from patients sensitive to Dermatophagoides pteronyssinus. Results showed that Der p 1 induced an increase in CD86 expression only on DCs from house dust mite--sensitive patients. This was also associated with a higher capacity to induce T-cell proliferation, a rapid increase in the production of proinflammatory cytokines, tumor necrosis factor--alpha and interleukin (IL)-1 beta, and the type 2 cytokine IL-10. No changes in the release of IL-12 p70 were induced by Der p 1. Finally, purified T cells from house dust mite-sensitive patients stimulated by autologous Der p 1--pulsed DCs preferentially produced IL-4 rather than interferon-gamma. These effects were abolished in the presence of the inactive precursor of Der p 1 (ProDer p 1). Taken together, these data suggest that DCs from house dust mite--sensitive patients, in contrast to DCs from healthy donors and from pollen-sensitive patients, exposed to Der p 1 play a pivotal role in the enhancement of the Th2 response associated with the allergic reaction developed in response to house dust mite exposure. (Blood. 2001;98:1135-1141)

Animals↗

PubMed2001

Histamine induces CD86 expression and chemokine production by human immature dendritic cells.

Mast cells and immature dendritic cells (DC) are in close contact in peripheral tissues. Upon activation, mast cells release histamine, a mediator involved in the immediate hypersensitivity reaction. We therefore tested whether histamine could affect human DC activation and maturation. Histamine induces CD86 expression on immature DC in a dose-dependent (significant at 10(-7) M) and transient manner (maximal after 24-h stimulation). Histamine also transiently up-regulates the expression of the costimulatory and accessory molecules, CD40, CD49d, CD54, CD80, and MHC class II. As a consequence, immature DC exposed for 24 h to histamine stimulate memory T cells more efficiently than untreated DC. In addition, histamine induces a potent production of IL-6, IL-8, monocyte chemoattractant protein 1, and macrophage-inflammatory protein 1alpha by immature DC and also up-regulates IL-1beta, RANTES, and macrophage-inflammatory protein 1beta but not TNF-alpha and IL-12 mRNA expression. Histamine activates immature DC through both the H1 and H2 receptors. However, histamine-treated DC do not have a phenotype of fully mature cells, as they do neither show significant changes in the expression of the chemokine receptors, CCR5, CCR7 and CXC chemokine receptor 4, nor expression of CD83 de novo. These data demonstrate that histamine activates immature DC and induces chemokine production, thereby suggesting that histamine, via stimulation of resident DC, may participate locally in T cell stimulation and in the late inflammatory reaction associated with allergic disorders.

Adjuvants, Immunologic↗

PubMed2001

Peroxisome proliferator-activated receptor gamma activators affect the maturation of human monocyte-derived dendritic cells.

Peroxisome proliferator-activated receptor gamma (PPARgamma ), a member of the nuclear receptor superfamily, has recently been described as a modulator of macrophage functions and as an inhibitor of T cell proliferation. Here, we investigated the role of PPARgamma in dendritic cells (DC), the most potent antigen-presenting cells. We showed that PPARgamma is highly expressed in immature human monocyte-derived DC (MDDC) and that it may affect the immunostimulatory function of MDDC stimulated with lipopolysaccharide (LPS) or via CD40 ligand (CD40L). We found that the synthetic PPARgamma agonist rosiglitazone (as well as pioglitazone and troglitazone) significantly increases on LPS- and CD40L-activated MDDC, the surface expression of CD36 (by 184% and 104%, respectively) and CD86 (by 54% and 48%), whereas it reduces the synthesis of CD80 (by 42% and 42%). Moreover, activation of PPARgamma resulted in a dramatic decreased secretion of the Th1-promoting factor IL-12 in LPS- and CD40L-stimulated cells (by 47% and 62%), while the production of IL-1beta, TNF-alpha, IL-6 and IL-10 was unaffected. Finally, PPARgamma ligands down-modulate the synthesis of IFN-gamma -inducible protein-10 (recently termed as CXCL10) and RANTES (CCL5), both chemokines involved in the recruitment of Th1 lymphocytes (by 49% and 30%), but not the levels of the Th2 cell-attracting chemokines,macrophage-derived chemokine (CCL22) and thymus and activation regulated chemokine (CCL17), in mature MDDC. Taken together, our data suggest that activation of PPARgamma in human DC may have an impact in the orientation of primary and secondary immune responses by favoring type 2 responses.

Chemokine CCL4↗

PubMed2000

Human dendritic cells in the severe combined immunodeficiency mouse model: their potentiating role in the allergic reaction.

Dendritic cells (DCs) are present in the lungs and airways of healthy and allergic subjects where they are exposed to inhaled antigens. After the uptake of antigens, DCs migrate to lymphoid organs where T cells initiate and control the immune response. The migratory properties of DCs are an essential component of their function but remain unclear in the situation of allergic diseases. To better understand the role of DCs in response to allergens, we first investigated their presence in an original experimental model of allergic asthma: the humanized severe combined immunodeficiency (SCID) mouse reconstituted with peripheral blood mononuclear cells from patients sensitive to Dermatophagoides pteronyssinus (Dpt). Human DCs were detected in lungs of mice developing an inflammatory pulmonary infiltrate and appeared to be mainly located in the alveolar spaces. In a second step, human DCs were generated in vitro from monocytes and injected into naive SCID mice exposed or not exposed to Dpt aerosols. Their migratory behavior was explored, as well as their potential role in modulating the IgE production after exposure to Dpt. After exposure to Dpt, the number of DCs present in airways decreased, while it increased into the spleen and thymus of the mice. The IgE production increased in the presence of DCs as compared with mice not injected with DCs. These results suggest that DCs may play a role in the pulmonary allergic reaction developed in response to Dpt in SCID mice.

Adoptive Transfer↗

PubMed2000

House dust mite-induced airway changes in hu-SCID mice.

SCID (severe combined immunodeficiency) mice reconstituted with peripheral blood mononuclear cells (PBMC) from Dermatophagoides pteronissynus (Dpt)-sensitive patients and exposed to Dpt aerosol (allergic hu-SCID mice) develop human IgE and pulmonary inflammation. The present study investigated concomitant changes in airway hyperresponsiveness (AHR). No significant difference in baseline airway responsiveness was seen between nonreconstituted SCID mice exposed or not to Dpt aerosol at Day 35. Allergic hu-SCID mice developed AHR (provocative dose of carbachol causing a 50% increase in lung resistance [PD(50) RL] = 96.33 +/- 16.88 microg/kg) compared with nonallergic hu-SCID mice (PD(50) RL = 242.03 +/- 37.84 microg/kg) and nonreconstituted SCID mice (PD(50) RL = 297.60 +/- 45. 60 microg/kg) exposed to Dpt aerosol. An inverse correlation was observed between PD(50) RL (Day 35) and total human IgE at Day 7 (r = -0.58) and Day 15 (r = -0.64). However, no correlation existed between PD(50) RL and human cell number in the lungs of allergic hu-SCID mice. Moreover, despite the absence of eosinophils, the bronchoalveolar lavage fluid (BALF) of allergic hu-SCID mice had more human interleukin-5 (IL-5) (3.28 +/- 0.40 pg/ml, n = 13) than nonallergic hu-SCID mice (< 0.5 pg/ml) which inversely correlated with the PD(50) RL (r = -0.61). No tumor necrosis factor-alpha (TNF-alpha), IL-6, or IL-4 was detected. These observations indicate that humanized allergic hu-SCID mice may develop AHR after exposure to the relevant allergen, suggesting that this model may improve our understanding of AHR, one characteristic feature of allergic asthma.

Airway Resistance↗

PubMed2000

Synergistic effect of diesel organic extracts and allergen Der p 1 on the release of chemokines by peripheral blood mononuclear cells from allergic subjects: involvement of the map kinase pathway.

The organic compounds of diesel exhaust particles (DEP-PAHs) have been shown to favor immunoglobulin production and bronchial hyperresponsiveness and to affect cytokine and chemokine productions. To evaluate if diesel exhaust could act in synergy with a house dust mite allergen (Der p 1), peripheral blood mononuclear cells from allergic patients were exposed to DEP-PAHs, with or without purified Der p 1. DEP-PAHs and Der p 1 separately induced an increase in interleukin (IL)-8, regulated on activation, normal T cells expressed and secreted (RANTES), and tumor necrosis factor-alpha concentrations. Interestingly, a synergy between the two stimuli was also observed. In the case of monocyte chemotactic protein (MCP)-1, DEP-PAHs reduced the release, whereas Der p 1 enhanced it. A simultaneous exposure led to reduced production as compared with allergen exposure alone, but still represented an increase as compared with the control exposure. Mitogen-activated protein (MAP) kinase Erk1/2 antagonist mainly inhibited the release of MCP-1, whereas MAP kinase p38 antagonist mainly suppressed the release of IL-8 and RANTES. Messenger RNA expression correlated with protein measurements. Moreover, supernatants from cells exposed to both DEP-PAHs and Der p 1 had a significant chemotactic activity on neutrophils and eosinophils. These findings suggest that simultaneous exposure of allergic patients to DEPs and allergens could result in high local chemokine levels via MAP kinase pathways activation, increasing the likelihood of reaching a critical threshold leading to the initiation of respiratory allergic symptoms.

Antigens, Dermatophagoides↗

PubMed1999

Estradiol coupling to human monocyte nitric oxide release is dependent on intracellular calcium transients: evidence for an estrogen surface receptor.

We tested the hypothesis that estrogen acutely stimulates constitutive NO synthase (cNOS) activity in human peripheral monocytes by acting on an estrogen surface receptor. NO release was measured in real time with an amperometric probe. 17beta-estradiol exposure to monocytes stimulated NO release within seconds in a concentration-dependent manner, whereas 17alpha-estradiol had no effect. 17beta-estradiol conjugated to BSA (E2-BSA) also stimulated NO release, suggesting mediation by a membrane surface receptor. Tamoxifen, an estrogen receptor inhibitor, antagonized the action of both 17beta-estradiol and E2-BSA, whereas ICI 182,780, a selective inhibitor of the nuclear estrogen receptor, had no effect. We further showed, using a dual emission microfluorometry in a calcium-free medium, that the 17beta-estradiol-stimulated release of monocyte NO was dependent on the initial stimulation of intracellular calcium transients in a tamoxifen-sensitive process. Leeching out the intracellular calcium stores abolished the effect of 17beta-estradiol on NO release. RT-PCR analysis of RNA obtained from the cells revealed a strong estrogen receptor-alpha amplification signal and a weak beta signal. Taken together, a physiological dose of estrogen acutely stimulates NO release from human monocytes via the activation of an estrogen surface receptor that is coupled to increases in intracellular calcium.

Calcium↗

PubMed1999

Effects of diesel organic extracts on chemokine production by peripheral blood mononuclear cells.

BACKGROUND: Polyaromatic hydrocarbons (PAHs) associated with diesel exhaust particles (DEPs) are found in the atmospheric urban pollution. Such compounds have been shown to favor IgE production, bronchial hyperresponsiveness, and airway inflammation. Chemokines are a group of chemotactic cytokines involved in the recruitment of inflammatory cells. OBJECTIVE: We investigated the effect of DEP-PAHs on the release and mRNA expression of IL-8, MCP-1, and RANTES by PBMCs obtained from healthy subjects. METHODS: Protein production in supernatants was assessed by ELISA, and mRNA expression was evaluated by semiquantitative RT-PCR. RESULTS: Secretion of IL-8 and RANTES increased in a dose-dependent manner with increasing concentrations of DEP-PAHs (range, 0.5 ng to 50 ng/mL). On the contrary, the release of MCP-1 was significantly inhibited, also in a dose-dependent manner. Messenger RNA production coding for IL-8, RANTES, and MCP-1 showed parallel variations to the production of the correspondent proteins. Effects of DEP-PAHs became significant at 7 hours and up to 48 hours time culture for MCP-1, and up to 24 hours time culture for IL-8 and RANTES. Moreover, supernatants from DEP-PAH-activated cells, compared with those of controls, exhibited a significantly enhanced chemotactic activity for neutrophils and eosinophils, which was significantly inhibited by pretreatment with anti-IL-8 and anti-RANTES neutralizing antibodies, respectively. CONCLUSION: These findings suggest that the chemokine pathways are modulated by DEP-PAHs at the transcriptional level, reinforcing the idea that the development of inflammatory reactions might be affected by diesel exhaust emission.

Cell Survival↗

PubMed1998

The house dust mite allergen, Dermatophagoides pteronyssinus, promotes type 2 responses by modulating the balance between IL-4 and IFN-gamma.

A common property of allergens is their potential to generate type 2 cytokine responses. To understand the mechanisms involved in this phenomenon, we have evaluated the polarizing potential of a major allergen, Dermatophagoides pteronyssinus 1 (Der p 1), in an heterologous immunization system using the glutathione S-transferase of the parasite Schistosoma mansoni (Sm28-GST) as immunogen. In previous studies, we showed that immunization with the Sm28-GST emulsified in CFA induced a nonpolarized immune response. In contrast, when alum was used as adjuvant, a type 2 immune response was induced against Sm28-GST. Using this experimental model, we examined whether the administration of Der p 1 together with Sm28-GST influenced the nonpolarized and/or the Th2 profiles induced by the CFA or the alum immunization, respectively. Our results showed that the introduction of Der p 1 in the CFA immunization protocol was associated with diminished anti-Sm28-GST IgG2a Ab titers, reduced IFN-gamma mRNA expression, and frequency of IFN-gamma-producing cells. In contrast, the introduction of Der p 1 in the alum protocol did not affect IL-4 or Ig isotype responses. The effect of Der p 1 was specific, since coimmunization with tetanus toxin fragment C did not affect the profile of the response against Sm28-GST. Furthermore, inactivation of Der p 1 reduced its ability to modify the immune response profile, suggesting that its protease activity played an important role in deviating the immune response. Our results suggest that the Der p 1 has the ability to modify the profile of an immune response by modulating the balance between the polarizing cytokines IL-4 and IFN-gamma.

Adjuvants, Immunologic↗

PubMed1998

Allergen-induced migration of human cells in allergic severe combined immunodeficiency mice.

Recently, we have shown that severe combined immunodeficiency (SCID) mice, intraperitoneally reconstituted with peripheral blood mononuclear cells (PBMC) from Dermatophagoides pteronyssinus (Dpt)-sensitive patients, produced human IgE and developed a pulmonary inflammatory-type reaction after exposure to allergen aerosol. In order to understand the potential mechanisms involved in the human cell migration in SCID mice, we analysed their phenotypic profile in the lungs, spleen and thymus, 2 months after Dpt inhalation. The human cell recruitment in these organs was found to be allergen-dependent as CD45+ human cells were only detected in hu-SCID mice after Dpt exposure. The composition of the pulmonary human T-cell infiltrate, preferentially memory (CD45RO), activated (human leucocyte antigen (HLA)-DR) and CD4+ cells, was similar to that described in asthmatic patients. However, CD20+ B cells were predominately recruited in the spleen and thymus and may be IgE-producing cells in the spleen. In the lungs, the percentage of human leucocytes expressing the alpha-chain of the lymphocyte function-associated antigen-1 (LFA-1) (CD11a) was higher than those of CD49d+ or CD54+ cells, in contrast to the spleen and thymus, suggesting a potential role of LFA-1 in the human cell migration towards SCID mice lung. In conclusion, this model could be useful in the study of factors implicated in the cellular migration towards the lymphoid organs during an allergic reaction.

Administration, Inhalation↗

PubMed1998

Tuberculin-induced delayed-type hypersensitivity reaction in a model of hu-PBMC-SCID mice grafted with autologous skin.

We have developed an animal model to study human delayed-type hypersensitivity reactions. Previous studies in humans have shown after tuberculin injection the presence of a mononuclear cell infiltration, with almost no eosinophils, associated with a preferential Th-1-type cytokine profile. Human skin graft obtained from tuberculin-reactive donors was grafted onto the back of severe combined immunodeficient mice. After healing, mice were reconstituted intraperitoneally with peripheral mononuclear cells. Tuberculin and diluent were injected intradermally, and skin biopsies were performed 72 hours later. Skin grafts were divided into two parts, one for immunohistochemistry and one for in situ hybridization studies. Immunohistochemistry was performed on cryostat sections using the alkaline phosphatase anti-alkaline phosphatase technique. In the tuberculin-injected sites as compared with the diluent-injected sites, there were significant increases in the number of CD45+ pan leukocytes and CD4+, CD8+, CD45RO+ T cells but not in CD68+ monocytes/macrophages and EG2 or MBP+ eosinophils. The activation markers CD25 and HLA-DR were up-regulated in the tuberculin-injected sites. In situ hybridization was performed using 35S-labeled riboprobes for interleukin (IL)-2, interferon (IFN)-gamma, IL-4, and IL-5. After tuberculin injection, a preferential Th-1-type cytokine profile was observed with significant increases in the numbers of IL-2 and IFN-gamma mRNA-expressing cells. These results are similar to those reported after tuberculin-induced delayed-type hypersensitivity in humans, suggesting that this model might be useful to study cutaneous inflammatory reaction.

Animals↗

PubMed1996

An in vivo model of allergic inflammation: pulmonary human cell infiltrate in allergen-challenged allergic Hu-SCID mice.

CB.17 severe combined immunodeficient (SCID) mice were used to establish a model of allergic pulmonary inflammation. SCID mice were intraperitoneally reconstituted with 10(7) peripheral blood mononuclear cells (PBMC) from patients sensitive to Dermatophagoides pteronyssinus (Dpt) and 2 weeks later were exposed to Dpt aerosols. After Dpt nebulization, SCID mice engrafted with PBMC from Dpt-sensitive patients developed a specific human IgE response as well as an intense pulmonary infiltrate of human cells. In contrast, SCID mice reconstituted with PBMC from patients allergic to grass pollen or from non-allergic donors failed to produce IgE or to exhibit a similar inflammatory response. The level of the IgE production was dependent on the IgE level of the allergic donor. In the lungs of the same allergic SCID mice, 2 months after Dpt inhalation, the cell infiltrate contained CD45+, CD45RO+, CD20+ and HLA-DR+ human cells. They were located in perivascular and peribronchial areas and disseminated in the mouse lung parenchyma. Moreover, mRNA IL-5+ cells and eosinophils were found in peribronchial infiltrates. The observations indicate that humanized allergic SCID mice may develop, after nebulization with the relevant allergen, immune reactions similar to those observed in man and suggest that SCID mice may represent a useful model to analyze the regulatory mechanisms of IgE-associated allergic diseases.

Administration, Inhalation↗

PubMed1995

Allergen-stimulated T lymphocytes from allergic patients induce vascular cell adhesion molecule-1 (VCAM-1) expression and IL-6 production by endothelial cells.

Adhesion of inflammatory cells to endothelium is a critical step for their transvascular migration to inflammatory sites. To evaluate the relationship between T lymphocytes (TL) and vascular endothelium, supernatants from allergen-stimulated TL obtained from patients sensitive to Dermatophagoides pteronyssinus (Dpt) versus healthy subjects were added to endothelial cell (EC) cultures. TL were stimulated by autologous-activated antigen-presenting cells (APC) previously fixed in paraformaldehyde to prevent monokine secretion. Two parameters were measured: the expression of adhesion molecule and the production of IL-6. Related allergen-stimulated TL supernatants from allergic patients induced an increase of VCAM-1 and intercellular adhesion molecule-1 (ICAM-1) expression when supernatants of the control groups (TL exposed to an unrelated allergen or not stimulated or TL obtained from healthy subjects) did not. E-selectin expression was not modulated whatever the supernatant added to EC culture. IL-6 production by EC was significantly enhanced after activation with related allergen-stimulated TL supernatants from allergics compared with control supernatants. Induction of VCAM-1 expression was inhibited by adding neutralizing antibodies against IL-4, whereas IL-6 production and ICAM-1 expression were inhibited by anti-interferon-gamma (IFN-gamma) antibodies. Enhanced production of IL-4 and IFN-gamma was detected in related allergen-stimulated TL supernatants from allergic subjects compared with the different supernatants. These data suggest that allergen-specific TL present in the peripheral blood of allergic patients are of Th1 and Th2 subtypes. Their stimulation in allergic patients may lead to the activation of endothelial cells and thereby participate in leucocyte recruitment towards the inflammatory site.

Adult↗

PubMed1994

Human IgE in SCID mice reconstituted with peripheral blood mononuclear cells from Dermatophagoides pteronyssinus-sensitive patients.

SCID mice were reconstituted with purified peripheral blood mononuclear cells from patients sensitive to Dermatophagoides pteronyssinus (Dpt). After immunization with a low dose of the related allergen, these human (Hu)-SCID mice may develop a specific IgE response. By using an IgE-dependent platelet assay and the related allergen Dpt, the human IgE was demonstrated to be functional. Indeed a high correlation was obtained between both parameters. No rise in human IgE level was detected within 3 wk after the immunization with an unrelated Ag. When mice were reconstituted with peripheral blood cells from nonallergic donors and immunized with the Dpt allergen, no human IgE production was evidenced in the serum of SCID mice. However, in both allergic Hu-SCID mice (reconstituted with cells from allergic patients) or in nonallergic Hu-SCID mice (reconstituted with cells from healthy donors), an IgG response was detectable. Finally by radioallergosorbent test, a specific IgE Ab response was detected after the first allergen challenge only in allergic Hu-SCID mice. Thus, without ethical constraints, SCID mice represent a useful model for analyzing the IgE response occurring in allergic patients.

Allergens↗