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  • 1
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The chronic inflammatory skin disease atopic eczema (AE) affects almost 15% of the population in many countries today. The pathogenesis of AE is not fully understood. A combination of genetic predisposition and environmental factors like microorganisms seems to contribute to the symptoms. The yeast Malassezia sympodialis is part of our normal skin micro flora but can act as an allergen and elicit specific IgE and T-cell reactivity in patients with AE. Recently, we identified a novel major M. sympodialis allergen, designated Mala s 11 (22.4 kDa), with sequence similarity to the mitochondrial enzyme manganese superoxide dismutase (MnSOD). Interestingly, Mala s 11 has a high degree of homology to human MnSOD. The aim of this study was to examine the effects of recombinant Mala s 11 on antigen-presenting dendritic cells. Monocyte-derived dendritic cells (MDDCs) from healthy blood donors were cultured with or without Mala s 11 for different time periods. It was found that the maturation marker CD83 and the costimulatory molecules CD80 and CD86 were upregulated on the MDDCs exposed to Mala s 11 for 24 h, as demonstrated by flow cytometry. Furthermore, coculture of MDDCs with Mala s 11 for 9 h induced an increased production of the inflammatory cytokines IL-6 (200-fold), TNF-α (100-fold) and IL-8 (sixfold), as detected by the cytometric bead array (CBA) analysis. Our results suggest that Mala s 11 affects the immune response through DC maturation and production of inflammatory cytokines. The potential cross-reactivity with human MnSOD needs to be explored and the exact role of Mala s 11 in the pathogenesis of AE assessed in clinical studies involving skin prick and atopy patch tests.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Atopic dermatitis (AD) is associated with increased levels of serum igE. and T-helper (Th) cells are thought to a play role in the pathogenesis. Individuals with AD often develop IgE antibodies against the yeast Pityrosporum orhiculare. a member of the normal cutaneous flora.Objective The role of P. orbiculare in atopic dermatitis was investigated by examining the T-cell reactivity for P. orbiculare.Methods Freshly isolated peripheral blood monoruclear cells (PBMC) were isolated from 10 AD patients with serum IgE antibodies against P. orbiculare, and from six healthy controls. The proliferative response after P. orbiculare stimulation, measured by [3H]thymidine incorporation, was examined in the PBMC and in T-cell clones (TCC) obtained from skin and blood of one patient. The cytokine profile of the TCC was determined by enzyme-linked immunosorhent assay (ELISA). radioimmunoassay (RIA) and reverse transcriptase-polymerase chain reaction (RT-PCR) following challenge with either P. orbiculare extract or anti-CD3 antibodies and phytohaemag-glutinin.Results The PBMC response to P. orbiculare was significantly higher in the AD patients than in the control group (P 〈 0.05). Twenty-nine out of 36 tested TCC derived from one responding patient were reactive for P. orhiculare. The clones were CD2+ and CD4+, except for one CD8+ blood clone. A majority of the TCC derived from lesional skin showed a Th2- or Th2/Th0-like cytokine profile. A co-expression of interIeukin-5 (IL-5) mRNA and II-13 mRNA was detected in five out of six P. orhicularc-reative clones analysed for their cytokinc gene expression with RT-PCR.Conclusion Our data suggest that P. orhiculare can induce a T-cell response in AD patients. The Th2-like profile of P. orbiculare-reactive TCC derived from lesional skin indicates that P. orhiculare may play a role in maintaining IgE-mediated skin inflammation in AD.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 27 (1997), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background We have previously identified two major allergens of Pityrosporum orbiculare and characterized these as 37 kDa and 67 kDa proteins.Objective In the present study we have investigated the presence and subcellular location of the 37 kDa and 67 kDa allergen components in various members of the genus Pityrosporum as well as in Candida albicans. Candida parapsilosis and Saccharomyces cerevisiae. Methods To detect both cell surface and intracellular expression of the allergens, flow cytometry and confocal laser scanning microscopy (CLSM) were used. The cells were stained with indirect immunofluorescent (IIP) or alkaline phosphatase antialkaline phosphatase (APAAP) methods using mouse monoclonal antibodies (MoAbs)Results Ninety-five per cent of the P. orbiculare (P. ovale) cells cultured for 4 days showed cell surface-binding of the anti-37 kDa MoAb and 88% of the cells bound the anti- 67 kDa MoAb when analysed with IIF and flow cytometry. It was found that the members of the genus Pityrosporum (Malassezia). P. pachydermatis and M. sympodialis, expressed the 37 kDa and 67 kDa allergens to a similar extent as did P. orbiculare. Less than 5% of the cells of the genus Candida and S. cerevisiae showed positive staining with the MoAbs, The CLSM revealed that the 37 kDa and the 67 kDa components were located to the cell wall and could not be detected inside the acetone fixed and APAAP stained yeast cells of the genus Pityrosporum. When the yeast cells were cultured for more than 4 days the expression of both allergens decreased significantly.Conclusion All three members of the genus Pityrosporum express the 37 kDa and 67 kDa major allergens on the cell surface, whereas these proteins could virtually not be detected in the Candida genus and S. cerevisiae.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 25 (1995), S. 0 
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background Previous characterization studies of Pityrosporum orbiculare allergens have led to contradictory results. In immunoblotting studies a range of IgE-bitiding proteins of 10–100kDa have been identified. In another study, however, the IgE-binding structures were claimed to be associated with high-molecular-weight polysaccharides or glycoproteins, presumably mannans or mannoproleins. Objective In the present study the reasons for these discrepancies were investigated. Methods P. orbiculare preparations were compared in IgE ELISA and IgE-inhibilion ELISA, as well as in immunoblotting with sera from atopic dermatitis patients. Results It was inferred that variations in the period of in vitro culture of P. orbiculare constituted the most important factor determining the different compositions of the resulting yeast cell extracts. After 2 days of culture a wide range of allergen if proteins was present but upon more prolonged culture (〉4 days) most proteins of 10- 100kDa were lost. Accordingly, the protein concentration of the extracts gradually declined from 40% to 25% between days 4 and 15 of culture. On the other hand, the carbohydrate content remained fairly constant (approximately 30%). Using inhibition ELISA it was demonstrated that the high-molecular-weight glycoproleins or poly-saccharides presumably involved in most of the IgE-binding capacity in extracts from old cultures, were also present in comparable concentrations in all extracts tested, even after culture for only 2 or 4 days. Conclusion Preparations obtained from the exponential phase of yeast cultures (2–4 days old), should preferably be used in studies of the IgE response to P. orbicularc.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Atopic dermatitis (AD) is a chronic inflammatory skin disease with increasing prevalence, though still little is known of the pathomechanisms and the causes of the disease. Patients with AD often have specific IgE reactivity to the yeast Malassezia furfur (M. furfur), present in the normal microflora on human skin.To investigate the possible interaction of immature and mature antigen-presenting dendritic cells with the yeast M. furfur and its allergenic components.Monocyte-derived dendritic cells (MDDCs) generated from human peripheral blood were allowed to interact with FITC-labelled whole M. furfur yeast cells, M. furfur extract, a recombinant allergen from M. furfur designated rMal f 5 and M. furfur mannan, in the absence of IgE antibodies. Interaction and uptake were detected using flow cytometry and confocal laser scanning microscopy.Internalization of M. furfur yeast cells and yeast components by immature MDDCs was found using confocal laser scanning microscopy. Results from flow cytometric studies showed that a median of 94% (range, 65–98%) of the immature CD1a+ MDDCs were M. furfur extract positive, 81% (75–97%) rMal f 5 positive and 93% (62–98%) mannan positive. Mature CD1a+ MDDCs were significantly less efficient in this respect, with the corresponding figures only 26% (6–37%, P 〈 0.01), 6% (2–15%, P 〈 0.05) and 32% (9–50%, P 〈 0.01), respectively. Uptake of the non-glycosylated rMal f 5 by immature CD1a+ MDDCs was decreased to 27% (15–38%) by inhibition of pinocytosis. The binding of M. furfur extract and mannan was inhibited in a dose-dependent manner by methyl-α-d-mannopyranoside, suggesting uptake via the mannose receptor.Human immature CD1a+ MDDCs can efficiently take up M. furfur and allergenic components from the yeast in the absence of IgE antibodies, implying that sensitization of AD patients to M. furfur can be mediated by immature dendritic cells in the skin.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The yeast Pityrosporum orbiculare (P. orbiculare) is a member of the normal human cutaneous flora, but it is also associated with several clinical manifestations of the skin. We have previously observed IgE-binding components in P. orbiculare extracts, using sera from patients with atopic dermatitis. In the present study, we raised several monoclonal antibodies (MoAbs) against P. orbiculare to characterize some of its antigens, and used Candida albicans (C. albicans) as a control. We obtained several IgGI MoAbs which specifically recognized P. orbiculare in ELISA. Two of these were selected for immunoblotting studies on P. orbiculare and two patterns of reactivity emerged. Firstly, one MoAb showed a distinct band at a molecular mass of 67 kDa. In the second pattern, a sharp band at about 37 kDa appeared. In contrast, the IgM antibodies raised reacted with a 14-kDa component; but they reacted with C. albicans in addition to P. orbiculare The IgGI antibodies seemed to react with proteins, as their ability to react in ELISA with extract pretreated with protease was greatly reduced. In contrast, IgM MoAbs were much less affected, suggesting that they recognized nonprotein components. To determine whether these MoAbs-binding components were also recognized by human IgE, we adopted a radioimmunoassay (RIA) using the MoAbs as catcher antibodies. Both the 67-kDa and the 37-kDa components were IgE-binding proteins. P. orbicular RAST positive sera were scored as positive in the RIA, whereas the control serum was not.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Allergy 58 (2003), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: Malassezia yeasts play a role in the pathogenesis of atopic eczema/dermatitis syndrome (AEDS). The revised genus Malassezia includes several species which all are natural habitants of the human skin. In this study, we evaluated the presence of immunoglobulin E (IgE) antibodies to different Malassezia spp. in AEDS patients to allow optimization of the characterization of the IgE antibody profile of IgE-associated AEDS.Methods: Ninety-six adult patients, with a clinical diagnosis of AEDS, were included in the study. Seventeen of the patients had IgE antibodies to M. sympodialis, ATCC 42132 (m70 ImmunoCAP, Pharmacia, Diagnostic AB, Uppsala, Sweden). The IgE antibodies to seven Malassezia spp. were measured and inhibition immunoblotting was performed to investigate whether M. sympodialis contains all the allergen components present in the other Malassezia spp.Results: Twenty per cent of 79 AEDS patients with a negative m70 ImmunoCAP test had IgE antibodies to at least one of the other six Malassezia spp. tested. Our inhibition studies indicated that Malassezia spp. to a great extent, share allergenic determinants. However, Malassezia species also contained species-specific allergens.Conclusion: The use of only one species of Malassezia is not sufficient to detect all patients IgE sensitized to Malassezia. To obtain an optimal allergen preparation both common allergenic components as well as species-specific allergens have to be considered.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary Background The yeast Malassezia is considered to be one of the factors that can contribute to atopic dermatitis (AD). Objectives To investigate the reactivity to Malassezia allergens, measured as specific serum IgE, positive skin prick test and positive atopy patch test (APT), in adult patients with AD. Methods In total, 132 adult patients with AD, 14 with seborrhoeic dermatitis (SD) and 33 healthy controls were investigated for their reactions to M. sympodialis extract and three recombinant Malassezia allergens (rMal s 1, rMal s 5 and rMal s 6). Results Sixty-seven per cent of the AD patients, but only one of the SD patients and none of the healthy controls, showed a positive reaction to at least one of the Malassezia allergens (extract and/or recombinant allergens) in at least one of the tests. The levels of M. sympodialis-specific IgE in serum correlated with the total serum IgE levels. Elevated serum levels of M. sympodialis-specific IgE were found in 55% and positive APT reactions in 41% of the AD patients with head and neck dermatitis. A relatively high proportion of patients without head and neck dermatitis and patients with low total serum IgE levels had a positive APT for M. sympodialis, despite lower proportions of individuals with M. sympodialis-specific IgE among these groups of patients. Conclusions These results support that Malassezia can play a role in eliciting and maintaining eczema in patients with AD. The addition of an APT to the test battery used in this study reveals a previously overlooked impact of Malassezia hypersensitivity in certain subgroups of AD patients.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 50 (1995), S. 0 
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Pityrosporum orbiculare and Candida albicans extracts were separated bySDS-PAGE, and IgE binding was detected by immunoblotting with 21 patient sera that were RAST positive to both yeasts. Cross-wise inhibition was performed of IgE binding of a serum pool containing IgE antibodies to both yeasts. The pool was mixed with serial dilutions of P. orbiculare or C. albicans extracts, and incubated with strips containing separated allergen. IgE binding was quantified by densitometric scanning and percent inhibition was calculated as well as the respective ratios between required extract concentration for 50% inhibition in heterologous compared to homologous inhibition for each component ‘inhibition ratio). Ten componentsof P. orbiculare were detected by more than 60% of the sera. IgE binding toC. albicans was weak, and only to four bands was IgE binding detected by more than 30% of the sera. The most important C. albicans allergen was a 48-kDa band, to which IgE of half of the patient sera bound. There was little inhibition of IgE binding to P. orbiculare with C. albicans. Thus, all but three components exhibited an inhibition ratio higher than 100.The inhibition ratio of the 48-kDa C. albicans compound was 50, thus indicating some degree of cross-reactivity. Significant cross-reactivity was shown by C. albicans compounds of 18, 24, 26, 34, and 38 kDa, the inhibition ratios of which were less than 10. There was some degree of cross-reactivity between apparent protein allergens of the two yeasts, but IgE antibodies to C. albicans donot merely reflect sensitization to P. orbiculare.
    Type of Medium: Electronic Resource
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