Increased expression of HLA-DR and CD86 in nasal epithelial cells in allergic rhinitics: antigen presentation to T cells and up-regulation by diesel exhaust particles

BACKGROUND: A proportion of nasal epithelial cells (NEC) in patients with allergic rhinitis (AR) are known to express the major histocompatibility complex Class II molecule (HLA-DR). OBJECTIVE: We hypothesized that NEC may play a role in antigen presentation to T cells. To elucidate the possible role of NEC in antigen presentation, we examined the expression of HLA-DR, CD80 and CD86 in NEC, their regulation by cytokines and the capacity of NEC to induce antigen-specific proliferation of T cells. METHODS: We examined the expression of HLA-DR, CD80 and CD86 in nasal epithelial scrapings of patients with seasonal allergic rhinitis (SAR) to Japanese cedar pollen pre-season and in-season, by immunohistochemistry. Next, we examined the effect of IL-1beta, TNF-alpha, (IFN-gamma), IL-4 alpha, IL-13 and diesel exhaust particles (DEP) on the HLA-DR, CD80 and CD86 expression in cultured nasal epithelial cells (CNEC), by flow cytometry. Further, we analysed the capacity of mite antigen (Der f II)-pulsed mitomycin-C-treated CNEC to induce proliferation of autologous T cells from patients with perennial allergic rhinitis. RESULTS: NEC constitutively expressed HLA-DR and CD86, but not CD80. The expression of HLA-DR and CD86 in NEC was significantly increased in-season, in patients with SAR as compared with that of pre-season. While IFN-gamma up-regulated the expression of HLA-DR, IL-1beta and TNF-alpha up-regulated the expression of CD86 in CNEC. Furthermore, in the presence of mite antigen, CNEC induced the proliferation of autologous peripheral blood T lymphocytes. Anti-CD86 and anti-HLA-DR monoclonal antibody but not anti-CD80 inhibited the epithelial cell-induced T cell proliferation. Stimulation with a combination of DEP and mite antigen significantly up-regulated HLA-DR and CD86 expression in CNEC. CONCLUSIONS: These studies suggest that NEC in patients with AR may play a role in antigen presentation through the enhanced expression of HLA-DR and CD86. Furthermore, these results suggest the possibility that DEP may enhance the antigen-presenting function of CNEC.     

Allergen-induced cytokine production, atopic disease, IgE, and wheeze in children

BACKGROUND: The early childhood allergen-induced immune responses associated with atopic disease and IgE production in early life are not well understood. OBJECTIVE: We assessed the relationship of allergen-induced cytokine production by PBMCs to both atopic disease and to IgE increase in a cohort of children with a parental history of allergy or asthma (n = 112) at a median of 2 years of age. We examined cockroach (Bla g 1)-induced, house dust mite (Der f 1)-induced, and cat (Fel d 1)-induced cytokine secretion, including secretion of IFN-gamma, IL-13, IL-10, and TNF-alpha. We investigated whether distinct cytokine patterns associated with atopic disease can be detected in immune responses of children. METHODS: PBMCs were isolated, and allergen-induced cytokine secretion was analyzed by means of ELISA. Atopic disease was defined as physician- or nurse-diagnosed eczema or hay fever. Increased IgE was defined as an IgE level of greater than 35 U/mL to dust mite, cockroach, cat, and egg white or a total IgE level of 60 U/mL or greater. RESULTS: Compared with children without atopic disease, children with atopic disease had lower Der f 1 (P =.005) and Bla g 2 (P =.03) allergen-induced IFN-gamma levels. Compared with children without increased IgE (n = 95), those with increased IgE (n = 16) had higher Der f 1-induced (P =.006) and Fel d 1-induced (P =.005) IL-13 levels and lower Bla g 2-induced (P =.03) IFN-gamma levels. Compared with children with neither atopic disease nor repeated wheeze, children with both atopic disease and repeated wheeze had lower levels of allergen-induced IFN-gamma (P =.01 for Der f 1 and P =.02 for Bla g 2) cytokine secretion. CONCLUSION: In young children at risk for asthma or allergy, decreased allergen-induced IFN-gamma secretion is associated with atopic disease and, in some cases, with increased IgE levels. Increased allergen-induced IL-13 secretion is most strongly associated with early life increase of IgE.     

Aluminium hydroxide down-regulates T helper 2 responses by allergen-stimulated human peripheral blood mononuclear cells

BACKGROUND: Aluminium hydroxide (alum) is a commonly used adjuvant for specific immunotherapy of allergic diseases. While alum is traditionally associated with murine Th2 sensitization, little is known about its effects on secondary allergic responses in humans. METHODS: We investigated the in vitro effects of alum on peripheral blood mononuclear cells (PBMC) from atopic donors. PBMC from 18 grass pollen-sensitive rhinitic subjects were stimulated with Phleum pratense (Phl p) in the presence or absence of alum. After 6 days culture, cytokine production was measured by ELISA and T cell proliferation by radiolabelled thymidine incorporation. The effect of alum on the expression of human leucocyte antigen and CD80/CD86 on cultured antigen-presenting cells was assessed by flow cytometry. RESULTS: PBMC cultured with Phl p and alum showed a significant decrease in both IL-5 and IL-13 production compared with allergen alone (P<0.005 and P<0.001, respectively), but no change in IFN-gamma or IL-12 production or proliferative responses. These alum-induced changes in T helper (Th)2 cytokine production were unaffected by the addition of neutralizing antibodies to IL-4 or IL-12. Culture of PBMC with alum induced increased expression of CD86 (P=0.004) and HLA (P=0.01) on monocytes while the expression of CD80 was decreased (P=0.02). SUMMARY: Alum down-regulates allergen-driven Th2 cytokine responses while Th1 cytokines are unaffected. These data confirm that alum is a useful adjuvant for inclusion in allergen immunotherapy vaccines.     

CD80 (B7-1) and CD86 (B7-2) antigens on house dust mite-specific T cells in atopic disease function through T-T cell interactions

BACKGROUND: CD80 (B7-1) and CD86 (B7-2) play an important role in antigen presentation to effector cells. Recent studies have demonstrated that these costimulatory molecules are also expressed on activated T cells. However, the functional role of CD80 and CD86 expressed on allergen-specific T cells in atopic diseases has not yet been clarified. OBJECTIVE: We sought to determine the functional role of CD80 and CD86 expressed on allergen-specific T cells in atopic diseases. METHODS: We assayed the expression of CD80 and CD86 on allergen-specific T-cell lines from patients with perennial allergic rhinitis stimulated by Dermatophagoides farinae-crude (Der f-c) antigen, 1 of the major allergens causing house dust mite allergy. T-cell proliferation induced by Der f-c-specific T-T cell interactions was measured, and the role of CD80 and CD86 in this proliferation was examined. In addition, we compared the proportion of CD45RO+CD86(+) T cells in primary culture of PBMCs stimulated by Der f-c antigen between patients with perennial allergic rhinitis and control subjects. RESULTS: On T-cell activation, CD86 antigen was upregulated earlier than CD80. Both CD80 and CD86 expressed on Der f-c-specific T cells could provide costimulatory signals to induce allergen-specific T-cell proliferation that was partially inhibitable by both anti-CD80 and anti-CD86 mAbs. The proportion of CD45RO+CD86(+) T cells in primary culture from atopic patients was significantly higher than that from control subjects. CONCLUSION: These results suggest that costimulatory molecules, such as CD80 and CD86, expressed on allergen-specific T cells may be involved in the amplification of allergen-specific immune responses through T-T cell interactions in atopic diseases.     

HLA-DR expression on neonatal monocytes is associated with allergen-specific immune responses

BACKGROUND: The specific mechanisms regulating priming of T-cell immunity to common allergens during early childhood remain to be elucidated, though increasing evidence indicates that antigen-presenting cell function is impaired in childhood. OBJECTIVE: Examine the relationship between HLA-DR expression on monocytes and B cells, allergen-specific T-cell responses at birth, and clinical outcomes at 2 years of age. METHODS: Blood mononuclear cells were obtained from 36 healthy neonates who were followed up clinically to the age of 2 years. Expression of HLA-DR by monocytes and B cells was determined at baseline and after in vitro exposure to IFN-gamma, a cytokine that is known to upregulate the expression of HLA-DR. Mononuclear cells were stimulated with endotoxin or a panel of inhalant and food allergens, and cytokine responses and lymphoproliferation were determined after 1 and 5 days, respectively. RESULTS: The magnitude of HLA-DR upregulation on IFN-gamma-stimulated cord blood CD14 + monocytes was consistently correlated with allergen-induced, but not mitogen-induced, lymphoproliferation at birth. HLA-DR upregulation on monocytes was also positively associated with endotoxin-induced IL-12 p70 synthesis (tau = 0.46; P < .001) but inversely related to mite- and ovalbumin-induced IL-13 synthesis ( P = .0006 and P < .003, respectively). HLA-DR expression on unstimulated cord blood monocytes was inversely associated with symptoms of atopic disease at the 2-year follow-up ( P = .015). In contrast, HLA-DR expression on B cells was not associated with these parameters of immune function. CONCLUSIONS: These findings suggest that the maturity of neonatal monocytes and their responsiveness to external stimuli are linked to differing patterns of immune reactivity at birth and to the risk of allergic symptoms in early childhood.     

MBL对树突状细胞体外分化成熟的影响

目的: 探讨甘露聚糖结合凝集素 (MBL)对人外周血单核细胞来源的树突状细胞 (MoDC)分化成熟的影响。方法: 以天然人MBL刺激MoDC, 在倒置显微镜下观察DC的形态; 用FACS分析DC的表型; 用 3H- TdR掺入法测定DC刺激同种异体T细胞增殖的能力; 以酵母多糖颗粒吞噬试验评估DC的抗原摄取能力; 用ELISA检测DC培养上清中IL- 12和TNF- α的含量。结果: MBL刺激的DC表面分子CD1a、CD83、CD40、CD80、CD86和MHC DR的表达均上调,摄取酵母多糖颗粒的能力降低, 激发初始T细胞增殖的能力加强, 分泌的IL- 12增多但几乎不分泌TNF- α。结论: MBL能诱导DC分化成熟, 提示其可能通过调节DC的功能而参与获得性免疫应答。     

Dexamethasone and cyclosporin A affect the maturation of monocyte-derived dendritic cells differently

In contrast to the confirmed effects of glucocorticoids (GCs) and cyclosporin A (CyA) on T cells, the effects of both agents on antigen-presenting cells (APCs), especially on dendritic cells (DCs), are still poorly understood. In this study, we cultured monocyte-derived DCs (MoDCs) under a variety of stimulations in the presence or absence of these immunosuppressants and compared their effects on the activation of MoDCs by these stimulations. The stimulations used were the following: three bacterial toxins, including lipopolysaccharide (LPS), staphylococcal enterotoxin A (SEA) and streptococcal pyrogenic exotoxin A (SPEA), the combination of IL-1beta and TNF-alpha, and an agonistic anti-CD40 antibody. All of these stimulations increased the expression of CD54, CD83, CD86, and HLA-DR antigen, and the production of TNF-alpha in MoDCs. When MoDCs were treated with dexamethasone (Dex) during the stimulation, Dex significantly suppressed the augmentation of CD86 expression and TNF-alpha production induced by all of these stimulations. In contrast, when MoDCs were treated with CyA, it inhibited only the effects induced by the superantigens, SEA and SPEA, but not that induced by LPS, the combination of cytokines, or anti-CD40 antibody. The augmentation of CD54 or HLA-DR antigen expression was not significantly suppressed by either Dex or by CyA. When we used MoDCs pretreated with each of these stimulations + Dex or + CyA as APCs, however, significant suppression of T cell proliferation was observed only in the case of the pretreatment with IL-1beta/TNF-alpha + Dex. The allogeneic T cell stimulation by MoDCs pretreated with the other combinations did not significantly differ from that treated with the stimulation alone. Our present study succeeded in demonstrating a clear difference between Dex and CyA in the activation of MoDCs. These differences may induce a significant difference in their final immunological responses.     

Effect of CD80 and CD86 on T Cell Cytokine Production

Conjugation of the T cell receptor (TCR) with antigen/MHC proteins must be accompanied by conjugation of T cell counterreceptors (CD28 or CTLA-4) with costimulatory molecules CD80 or CD86 (B7-1 or B7-2) on antigen presenting cells (APC) to avert T cell anergy, and to provide essential signals for T cell activation and cytokine production. However, T cells and APC express changing patterns of counterreceptors and costimulatory molecules during the immune response. To determine the involvement of CD80 and CD86 in costimulation of T cell cytokine production, T cells were incubated with peritoneal exudate macrophages, which express CD80 and CD86, and stimulated in vitro for 48 or 72 hrs with anti-CD3 in the presence or absence of blocking antibody to CD80 or CD86. Alternatively, enriched anti-CD3 stimulated T cells were costimulated with antibody to CD28 and CTLA-4. Production of T cell IL-2, IL-4, and IL-5 was depressed in the presence of anti-CD86 but not anti-CD80. Production of IFN-γ was significantly blocked by either anti-CD80 and anti-CD86. Anti-CD28 was a potent costimulator of IFN-γ and IL-2 production, but a less potent costimulator of IL-4 and IL-5 production. The data suggest that T cell counterreceptors and APC costimulatory molecules act with varying efficacies at stimulating production of T cell cytokines.     

Effect of CD80 and CD86 on T Cell Cytokine Production

Conjugation of the T cell receptor (TCR) with antigen/MHC proteins must be accompanied by conjugation of T cell counterreceptors (CD28 or CTLA-4) with costimulatory molecules CD80 or CD86 (B7-1 or B7-2) on antigen presenting cells (APC) to avert T cell anergy, and to provide essential signals for T cell activation and cytokine production. However, T cells and APC express changing patterns of counterreceptors and costimulatory molecules during the immune response. To determine the involvement of CD80 and CD86 in costimulation of T cell cytokine production, T cells were incubated with peritoneal exudate macrophages, which express CD80 and CD86, and stimulated in vitro for 48 or 72 hrs with anti-CD3 in the presence or absence of blocking antibody to CD80 or CD86. Alternatively, enriched anti-CD3 stimulated T cells were costimulated with antibody to CD28 and CTLA-4. Production of T cell IL-2, IL-4, and IL-5 was depressed in the presence of anti-CD86 but not anti-CD80. Production of IFN-γ was significantly blocked by either anti-CD80 and anti-CD86. Anti-CD28 was a potent costimulator of IFN-γ and IL-2 production, but a less potent costimulator of IL-4 and IL-5 production. The data suggest that T cell counterreceptors and APC costimulatory molecules act with varying efficacies at stimulating production of T cell cytokines.     

Altered phenotype and function of blood dendritic cells in multiple sclerosis are modulated by IFN-beta and IL-10.

Multiple sclerosis (MS) is assumed to result from autoaggressive T cell-mediated immune responses, in which T helper type 1 (Th1) cells producing cytokines, e.g. IFN-gamma and lymphotoxin promote damage of oligodendrocyte-myelin units. Dendritic cells (DCs) as potent antigen presenting cells initiate and orchestrate immune responses. Whether phenotype and function of DCs with respect to Th1 cell promotion are altered in MS, are not known. This study revealed that blood-derived DCs from MS patients expressed low levels of the costimulatory molecule CD86. In addition, production of IFN-gamma by blood mononuclear cells (MNCs) was strongly enhanced by DCs derived from MS patients. IFN-beta and IL-10 inhibited the costimulatory capacity of DCs in mixed lymphocyte reaction (MLR) and showed additive effects on suppression of IL-12 production by DCs. Correspondingly, DCs pretreated with IFN-beta and IL-10 significantly suppressed IFN-gamma production by MNCs. IFN-beta in vitro also upregulated CD80 and, in particular, CD86 expression on DCs. In vitro, anti-CD80 antibody remarkably increased, while anti-CD86 antibody inhibited DC-induced IL-4 production in MLR. We conclude that DC phenotype and function are altered in MS, implying Th1-biased responses with enhanced capacity to induce Th1 cytokine production. In vitro modification of MS patients' DCs by IFN-beta and IL-10 could represent a novel way of immunomodulation and of possible usefulness for future immunotherapy of MS.     

Triggering CD101 molecule on human cutaneous dendritic cells inhibits T cell proliferation via IL-10 production

Since the CD101 molecule is expressed on a major subpopulation of HLA-DR(+), CD1a(+), CD1c(+) cutaneous dendritic cells (DC), we studied the functional role of CD101 on cutaneous DC. Anti-CD101 monoclonal antibody (mAb) inhibited the proliferation of T cells induced by cutaneous DC. There was a synergistic inhibition between anti-CD101 mAb and anti-CD86/anti-CD80 mAb. Anti-CD101 mAb exerted its inhibitory effect when binding to the CD101 expressed on cutaneous DC. No positive role of CD101 putative ligand expressed by T cells in T cell proliferation was demonstrated, as T cells proliferated in response to soluble anti-CD3 mAb in the presence of CD86-transfected cells but not in the presence of CD101-transfected cells. Of major significance is the fact that IL-10 was produced by cutaneous DC after CD101 triggering with anti-CD101 mAb, while IL-10 secretion was up-regulated in mixed cutaneous DC-T cell cultures after CD101 triggering. Furthermore, IL-10-neutralizing mAb could reverse the inhibition induced by anti-CD101 mAb. Our results demonstrate that the CD101 triggering on cutaneous DC inhibits T cell proliferation via IL-10 production, suggesting an important regulatory role played by the CD101 molecule on DC during T cell activation.     

Requirement of CD28-CD86 co-stimulation in the interaction between antigen-primed T helper type 2 and B cells

The interaction between CD28 and its ligands, CD80 and CD86, is crucial for an optimal activation of antigen-specific T cells. However, the requirement of CD80 or CD86 co-stimulation in Th2 cell differentiation and activation is controversial. Freshly isolated murine CD4+ and CD8+ T cells were incubated with P815 transfectants expressing a similar level of either CD80 or CD86 in the presence of anti-CD3 mAb. Both CD80 and CD86 co-stimulated the proliferation of CD4+ and CD8+ T cells at comparable time-kinetics and magnitude, but CD86 alone was able to co- stimulate IL-4 and especially IL-10 production in CD4+ T cells. In typical Th2-dependent immune responses elicited by Nippostrongylus brasillensis infection, the anti-CD86 mAb treatment but not the anti- CD80 mAb treatment efficiently inhibited antigen-specific IgE and IgG1 production, which was accompanied with the reduced IL-4 production. Our results suggest that CD86 co-stimulation plays a dominant role not only in the primary activation of Th2 cells but also in the secondary interaction between antigen-primed Th2 cells and B cells.      

CD40-dependent and -independent activation of human tonsil B cells by CpG oligodeoxynucleotides

Immunostimulatory CpG oligodeoxynucleotide (CpG-ODN) sequences are known to directly activate B cells. We investigated the expression of the CpG receptor, Toll-like receptor 9 (TLR9), in human tonsil B cells, and determined functional responses following stimulation by a well-characterized stimulatory CpG-containing ODN sequence in the human immune system, ODN 2006. Tonsil B cells were found to express high amounts of TLR9 mRNA and protein, and exposure of B cells to CpG-ODN but not to an inactive control ODN induced a concentration- and time-dependent up-regulation of the activation markers CD23, CD25, CD40, CD54, CD80, CD86 and HLA-DR. However, significant induction of proliferation and the release of IL-6, IL-10, IgG and IgM were only noted when B cells were co-incubated with irradiated CD40L-expressing CHO cells. Endogenous IL-10 was identified as a critical mediator of Ig production, whereas all activating effects were independent of IL-6. Further, CpG-ODN counteracted IgE production induced by IL-4. Collectively, these findings suggest a synergistic role of the TLR9/CD40 system and a critical role for the immunomodulatory cytokine IL-10 in the orchestration of CpG-ODN-induced responses in B lymphocytes.     

Aberrant interleukin (IL)-4 and IL-5 production in vitro by CD4+ helper T cells from atopic subjects.

The cytokine secretion profiles of T cell lines (TCL) specific for purified protein derivative (PPD) or streptokinase (SK), contemporarily derived from nine atopic and nine nonatopic individuals, were compared. Upon stimulation with phorbol myristate acetate (PMA) plus anti-CD3 monoclonal antibody (mAb), all TCL from both atopics and nonatopics produced interleukin (IL)-2 and interferon (IFN)-gamma. The mean IL-2 production by PPD- or SK-specific TCL from both atopics and nonatopics was similar, whereas the mean IFN-gamma production by TCL derived from atopics was significantly lower. In addition, both PPD- and SK-specific TCL from atopics produced detectable amounts of IL-4 and IL-5, whereas the corresponding TCL derived from nonatopics did not. A total number of 107 and 99 PPD-specific CD4+ T cell clones (TCC) were then derived from TCL of 4 atopic and 4 nonatopic donors and assessed for their profile of cytokine production in response to stimulation with either PMA plus anti-CD3 mAb or the specific antigen. Under both these experimental conditions, virtually all PPD-specific TCC from both atopic and nonatopic individuals produced IL-2 and IFN-gamma. In contrast, the great majority of PPD-specific TCC derived from nonatopic individuals did not produce IL-4 and IL-5, whereas high proportions of PPD-specific TCC derived from atopic donors displayed the ability to produce noticeable amounts of IL-4 and IL-5 besides IL-2 and IFN-gamma. These data indicate that CD4+ T cells from atopic individuals are able to produce IL-4 and IL-5 in response to bacterial antigens, such as PPD and SK, that usually evoke responses with a restricted type-1 T helper (Th1)-like cytokine profile in nonatopic individuals. Aberrant IL-4 production by Th cells may represent one of the immune alterations responsible for enhanced IgE antibody production in atopic people.     

The antigen-presenting environment in normal and human papillomavirus (HPV)-related premalignant cervical epithelium

The activation of HPV-specific T cells within the cervical microenvironment is likely to play an important part in the natural history of cervical intraepithelial neoplasia (CIN). The extent and the type of T cell activation will depend critically on the expression of MHC, costimulatory cell surface molecules and cytokines by keratinocytes and Langerhans cells within the cervical lesion. Expression of MHC class II (HLA-A-DR and -DQ), costimulatory/adhesion molecules (CD11a/18, CD50, CD54, CD58 and CD86) and cytokines (tumour necrosis factor-alpha (TNF-alpha) and IL-10) was therefore investigated by immunohistochemistry in normal squamous epithelium (n = 12), low-grade (n = 23) and high-grade (n = 18) squamous intraepithelial lesions of the cervix. CIN progression was associated with de novo expression of HLA-DR and CD54, and increased expression of CD58 by keratinocytes. However, significantly, there was no expression of any adhesion/costimulation molecule by epithelial Langerhans cells in any cervical biopsy studied. Furthermore, TNF-alpha, a potent activator of Langerhans cells, was expressed constitutively by basal keratinocytes in normal cervix (12+/12). but expression of this cytokine was absent in a number of CIN samples (20+/23 for low-grade, 12+/18 for high-grade CIN). Conversely, the suppressive cytokine IL-10 was absent in normal epithelium (0+/12), but was up-regulated in a number of CIN lesions (12+/23 for low-grade; 8+/18 for high-grade CIN). The restricted expression of costimulation/adhesion molecules and the nature of the cytokine microenvironment within the epithelium may act to limit effective immune responses in some CIN lesions.     

CD28 interactions with either CD80 or CD86 are sufficient to induce allergic airway inflammation in mice.

Previous studies have shown that the pan CD28/cytotoxic T lymphocyte antigen (CTL)A-4 antagonist CTLA4 immunoglobulin (Ig) inhibits eosinophilic airway inflammation in Schistosoma mansoni-sensitized and airway-challenged mice. In the present study, the importance of CD28 as well as the individual roles of CD80 and CD86 were examined in this system using wild-type and CD28 knockout (KO) mice. Unlike wild-type controls, CD28KO mice did not produce systemic IgE or eosinophilic airway inflammation after antigen challenge. However, a lymphocytic infiltrate and continued production of interferon-gamma was observed in these animals. Thus, CD28 is not essential for the initial recruitment of lymphocytes into antigen-challenged airways but critically regulates the allergic T-helper 2 phenotype. We next determined by polymerase chain reaction and flow cytometry that CD80 and CD86 molecules are constitutively expressed in the naive murine lung and on eosinophils in the allergic lung, suggesting a potential important role for both ligands in the development of asthma. Combined anti-CD80/anti-CD86 treatment throughout the antigen challenge period fully blocked the development of allergic airways, whereas a partial reduction was observed in mice treated with either anti-CD80 or anti-CD86 antibody alone. However, only anti-CD86 blocked systemic IgE production. Therefore, signaling through either CD80 or CD86 is sufficient to generate a partial local allergic response, whereas CD86 costimulation is essential to induce systemic allergic (IgE) reactions. Finally, combined anti-B7 monoclonal antibody treatment after sensitization reduced airway eosinophilia and interleukin (IL)-4/IL-5 cytokine secretion consistent with an ongoing role for CD28/B7 interactions in the effector phase of the disease. These results emphasize the importance of differential B7 expression on different cells and in different organs on subsequent CD28/B7-mediated immune events, including the potential for CD28/B7 blockade in the treatment of atopic airway disease in people.     

The allergenic yeast Malassezia furfur induces maturation of human dendritic cells

BACKGROUND: The yeast Malassezia furfur (M. furfur), present in the normal microflora of human skin, can act as an allergen that incites specific IgE reactivity and T cell proliferation in atopic dermatitis (AD) patients. The role of antigen presenting dendritic cells (DCs) in the onset and maintenance of AD is not well established. OBJECTIVE: The objective of the present study was to assess whether the interaction of M. furfur with human DCs will result in DC maturation, cytokine production and lymphocyte proliferation. METHODS: Monocyte-derived dendritic cells (MDDCs) were generated from human peripheral blood. Immature MDDCs were cultured with or without M. furfur or plastic beads, and with or without CD40L stimulation. Interaction of yeast cells by MDDCs was studied by time-lapse photography and cytokines were detected in culture supernatants with ELISA. The ability of MDDCs pre-incubated with M. furfur to induce proliferation in autologous lymphocytes was measured by [(3)H]-thymidine incorporation. RESULTS: Time-lapse photography showed that the majority of immature MDDCs internalized whole M. furfur yeast cells within 1 h. The presence of M. furfur induced maturation (CD83 expression) of MDDCs, and up-regulation of the costimulatory molecules CD80 and CD86. Production of TNF-alpha, IL-1 beta and IL-18 by MDDCs increased significantly (P < 0.05 for TNF-alpha and IL-1 beta, and P < 0.01 for IL-18) after the addition of M. furfur, while IL-10 and IL-12p70 levels remained unaltered. The CD40L-stimulated IL12p70 production by MDDCs was decreased in the presence of M. furfur (P < 0.05). Finally, immature MDDCs pre-incubated with M. furfur induced a proliferative response in autologous CD14-depleted peripheral blood mononuclear cells, in a dose-dependent manner. CONCLUSION: The data indicate that immature MDDCs can internalize the opportunistic yeast M. furfur. This process was associated with MDDC maturation, production of pro-inflammatory and immunoregulatory cytokines, which might favour induction of a Th2-type immune response, and a capacity to stimulate lymphocyte proliferation. This chain of events most likely contributes to the inflammatory reaction in AD.     

Ebastine inhibits T cell migration, production of Th2-type cytokines and proinflammatory cytokines

BACKGROUND: Cytokine imbalance and cellular migration to inflammatory sites are critical components of allergic diseases. Redirecting cytokine imbalance and inhibiting cell migration therefore represent important therapeutic strategies for the treatment of these disorders. OBJECTIVES: To study the in vitro effect of ebastine, a novel non-sedating H1 receptor antagonist, on cytokine secretion and migration of activated T cells, as well as production of pro-inflammatory cytokines by macrophages. METHODS: Peripheral T cells obtained from healthy volunteers were cultured in wells coated with the combination of anti-CD3 monoclonal antibody (mAb) and anti-CD26 mAb, anti-CD3 mAb and anti-CD28 mAb, or anti-CD3 mAb with PMA, in the presence or absence of ebastine. T cell proliferation and the production of cytokines were measured by [3H]thymidine incorporation assay and ELISA, respectively. In addition, transendothelial migration of T cells and production of pro-inflammatory cytokines by macrophages were examined. RESULTS: Ebastine inhibited T cell proliferation and the production of IL-4, IL-5, IL-6, and TNF-alpha by T cells under each co-stimulatory condition tested, whereas it exhibited no effect on the production of IL-2 or IFN-gamma. In addition, T cell migration and the production of such pro-inflammatory cytokines as TNF-alpha and IL-6 by macrophages were inhibited by ebastine. CONCLUSIONS: These results indicate that ebastine has a specific inhibitory effect on Th2-type cytokine production. Moreover, ebastine inhibited T cell migration and pro-inflammatory cytokine production by T cells and macrophages, suggesting that ebastine might be useful for the treatment of T cell-mediated allergic inflammatory disorders, including asthma, atopic dermatitis, and Th2-type autoimmune diseases.     

The Malassezia sympodialis allergen Mala s 11 induces human dendritic cell maturation, in contrast to its human homologue manganese superoxide dismutase

BACKGROUND: Recently, we identified a major Malassezia sympodialis allergen, Mala s 11, which displays a high degree of DNA sequence homology to human manganese superoxide dismutase (hMnSOD). In atopic eczema patients sensitized to M. sympodialis, hMnSOD can elicit eczematous reactions and positive skin prick tests, suggesting cross- reactivity to Mala s 11 based on molecular mimicry. The objective of the current study was to compare the influence of Mala s 11 and hMnSOD on human dendritic antigen-presenting cells. METHODS: Monocyte-derived dendritic cells (MDDCs) from healthy blood donors were co-cultured with recombinant Mala s 11 (rMala s 11), recombinant hMnSOD (rhMnSOD), lipopolysaccharide or cultured in medium alone. Phenotypic changes were analysed using flow cytometry and allogeneic lymphocyte proliferation assays. Cytokine release into culture supernatants was investigated using cytometric bead array. RESULTS: Whereas rhMnSOD did not affect the MDDC phenotype, rMala s 11 up-regulated the maturation marker CD83, the co-stimulatory molecules CD40, CD80, CD86 and HLA-DR to a similar extent as lipopolysaccharide. Furthermore, rMala s 11, but not rhMnSOD, induced significantly higher levels of TNF-alpha, IL-6, IL-8, IL-10 and IL-12p70 in the culture supernatants at 24 h in comparison with MDDCs cultured in medium alone. Finally, MDDCs pre-incubated with rMala s 11 induced a significantly higher proliferation of allogeneic CD14-depleted peripheral blood monocytes than MDDCs pre-incubated with rhMnSOD. CONCLUSION: Our results suggest that Mala s 11, but not hMnSOD, affects the immune response of healthy individuals through dendritic cell maturation and cytokine release. This indicates that dendritic cells possess the ability to distinguish between Mala s 11 and its human homologue MnSOD.