Influence of culture period on the allergenic composition of Pityrosporum orbiculare extracts

The role of Malassezia in atopic dermatitis affecting the head and neck of adults

Atopic dermatitis is a common chronic skin condition. A subset of patients with head and neck dermatitis may have a reaction to Malassezia flora fueling their disease. Although there are no documented differences in Malassezia species colonization, patients with head and neck atopic dermatitis are more likely to have positive skin prick test results and Malassezia-specific IgE compared with healthy control subjects and patients with atopy without head and neck dermatitis. There is no clear relationship with atopy patch testing. The reaction to Malassezia is likely related to both humoral- and cell-mediated immunity. Clinically, Malassezia allergy may be suspected in patients with atopic dermatitis and: (1) head and neck lesions; (2) exacerbations during adolescence or young adulthood; (3) severe lesions recalcitrant to conventional therapy; and (4) other atopic diseases. There is literature to suggest that these patients will benefit from a 1- to 2-month course of daily itraconazole or ketoconazole followed by long-term weekly treatment.

Mala s 12 is a major allergen in patients with atopic eczema and has sequence similarities to the GMC oxidoreductase family

BACKGROUND

Atopic eczema (AE) is a chronic inflammatory skin disorder, characterized by impaired skin barrier and itch. The yeast Malassezia belongs to the normal human skin microflora and can induce IgE- and T-cell-mediated allergic reactions in AE patients. Previously, we have identified several IgE-binding components in Malassezia sympodialis extract.

METHODS

Here, we report cloning, production and characterization of a M. sympodialis 67-kDa allergen.

RESULTS

The sequence of the 67-kDa protein, termed Mala s 12, showed sequence similarity to the glucose-methanol-choline (GMC) oxidoreductase enzyme superfamily and was expressed as a recombinant protein in Escherichia coli. The purified protein bound flavin adenine dinucleotide with 1:1 stoichiometry per monomer of protein. The protein-bound flavin showed an extinction coefficient at 451 nm of 11.3 mM(-1)cm(-1). The recombinant 67-kDa protein did not show any enzymatic activity when tested as oxidase or dehydrogenase using choline, glucose, myo-inositol, methanol, ethanol, 1-pentanol, benzyl alcohol, 2-phenylethanol, cholesterol or lauryl alcohol as possible substrates. Recombinant Mala s 12 was recognized by serum IgE from 13 of 21 (62%) M. sympodialis-sensitized AE patients indicating that the 67-kDa component is a major allergen.

CONCLUSIONS

The data show that Mala s 12 has sequence similarity to the GMC oxidoreductase family and is a major allergen in AE patients.

Sensitization to the Yeast Malassezia Sympodialis Is Specific for Extrinsic and Intrinsic Atopic Eczema

The opportunistic yeast Malassezia sympodialis belongs to the normal cutaneous flora but can also cause IgE-mediated sensitization in patients suffering from atopic eczema (AE). We investigated 706 individuals by ImmunoCAPm70 and skin-prick tests with a crude M. sympodialis extract. In AE patients, we further performed skin prick tests, atopy patch tests, ELISA, and peripheral blood mononuclear cells proliferation assays with recombinant M. sympodialis allergens (rMala s 1 and 5-9). In 52/97 patients with AE-specific IgE against M. sympodialis was detectable. Almost no reactivity to M. sympodialis was seen in patients suffering from other allergic diseases (4/571) and no reactivity at all was seen in healthy controls (0/38). Skin tests showed variable recognition patterns against the different molecular structures with a predominant sensitization to rMala s 1, 5, 6, and 9, confirmed also by specific serum IgE to these allergens. Interestingly, IgE- and T-cell-mediated reactivity against M. sympodialis was also found in patients with the intrinsic form of AE. Thus, sensitization to M. sympodialis is specific for AE patients and occurs in both the extrinsic and intrinsic variant of eczema. Recombinant yeast allergens represent a useful tool to study molecular structures and differential sensitization patterns in the pathogenesis of AE.

Malassezia sympodialis differently affects the expression of LL-37 in dendritic cells from atopic eczema patients and healthy individuals

BACKGROUND

Atopic eczema (AE) is a multifactorial disease, which has increased in prevalence. The skin-colonizing yeast Malasezzia sympodialis can induce IgE- and T-cell reactivity in patients with AE. LL-37 is an endogenous peptide antibiotic belonging to the cathelicidin family. The aim of this study was to examine whether exposure to M. sympodialis would affect the expression of LL-37 in dendritic cells.

METHODS

The presence of LL-37 was analyzed in monocyte-derived dendritic cells (MDDCs) generated from healthy individuals and patients with AE by Western blotting and the corresponding cDNA by real-time quantitative RT-PCR. Antibacterial activity was measured with an inhibition zone assay in fractions after reverse phase chromatography.

RESULTS

For the first time we here present data, showing that LL-37 is produced by MDDCs. Notably, the secretion of LL-37 was substantially enhanced in M. sympodialis-exposed MDDCs generated from patients with a high degree of eczema, as measured by SCORAD, compared to healthy controls and patients with a low SCORAD. The relative expression of LL-37 transcript in MDDCs generated from patients was up-regulated after 1 h of exposure to M. sympodialis and declined gradually at the time points analyzed, whereas the transcription was unaffected in the MDDCs of healthy controls.

CONCLUSIONS

Our results suggest that M. sympodialis can trigger the innate immune response differently in patients with AE and healthy individuals. The enhanced LL-37 secretion from the MDDCs in the patients with AE may reflect the severity of their inflammatory response to M. sympodialis.

Canine serum immunoreactivity to M. pachydermatis in vitro is influenced by the phase of yeast growth

In western immunoblotting studies of canine sera using Malassezia pachydermatis extracts, the reported patterns of immunoreactivity vary between different laboratories. Because the duration of culture influences the antigenic composition of lipid-dependent Malassezia spp. when probed with human sera, we investigated whether the in vitro growth phase of M. pachydermatis influences immunoreactivity using canine sera. Extracts of M. pachydermatis CBS 1879 grown in Sabouraud's liquid medium at 37 degrees C for 2, 4, 6, 8 and 10 days were prepared by mechanical disruption, centrifugation, dialysis and lyophilization. Yeast growth phase was assessed by sequential colony counts and optical density measurements. Patterns of IgG immunoreactivity in high (n = 3) and low (n = 3) titre sera were compared using extracts prepared at each time point by sodium dodecyl sulphate polyacrylamide gel electrophoresis and western immunoblotting. Protein bands of 62 and 49 kDa were recognized by all sera, and 98 and 68 kDa bands were recognized by five sera. Proteins of 188, 66, 58, 57, 38, 28 and 17 kDa were only recognized by high titre sera. All high titre sera used recognized more bands in exponential phase (d2) extracts when compared with decline phase (d8-d10) extracts, and two of these sera showed most bands in stationary phase (d4-d6) extracts. Bands of 62 and 57 kDa were primarily detected in exponential and early stationary phase extracts. There is variation in antigenic expression in different growth phases of M. pachydermatis, which might explain discrepancies between previous laboratory studies of canine immunity to this yeast.

Cloning, expression and characterization of two new IgE-binding proteins from the yeast Malassezia sympodialis with sequence similarities to heat shock proteins and manganese superoxide dismutase

Malassezia sympodialis is an opportunistic yeast that colonizes human skin and may induce IgE and T cell reactivity in patients with atopic eczema/dermatitis syndrome (AEDS). Previously, we have cloned and expressed six recombinant allergens (rMala s 1 and rMala s 5 to rMala s 9) from this yeast. By combining high throughput screening and phage surface display techniques, 27 complete and partial IgE-binding clones of M. sympodialis have been identified. Here we enlarged the panel of recombinant M. sympodialis allergens by RACE-PCR, cloning and nucleotide sequencing to obtain the coding sequences of two new IgE-binding clones. The coding sequences of one of the clones showed similarity to the heat shock protein (HSP) family and the other to manganese superoxide dismutase (MnSOD), and both had a high degree of homology to human counterparts. The coding sequences were expressed in Escherichia coli as six-histidine tagged recombinant proteins and generated products with molecular masses of 86.1 kDa for HSP and 22.4 kDa for MnSOD. Their IgE-binding frequencies were shown to be 69% and 75%, respectively, to 28 sera from AEDS patients with serum IgE to M. sympodialis extract, indicating that HSP and MnSOD are major M. sympodialis allergens. In inhibition immunoblotting, M. sympodialis extract could inhibit the binding of serum IgE from AEDS patients to rHSP and rMnSOD in a concentration-dependent manner. The high frequency of sera from AEDS patients, showing IgE binding to both HSP and MnSOD, indicates that these allergens, designated Mala s 10 and Mala s 11, could play a role in AEDS.

Detection of Mala f and Mala s allergen sequences within the genus Malassezia

Malassezia species are opportunistic yeasts that are involved in the pathogenesis of a number of skin diseases including atopic eczema/dermatitis syndrome. Previously, we cloned six allergens from Malassezia sympodialis isolate ATCC 42132; these allergens are designated Mala s 1, and Mala s 5-Mala s 9. Three additional allergens, Mala f 2-Mala f 4, have been isolated from M. furfur by other investigators. The objective of the present study was to investigate the presence of these Mala sequences in seven Malassezia species. Genomic DNA amplification by PCR and sequencing showed that M. globosa, M. obtusa and M. sympodialis contain DNA sequences corresponding to all the allergens except Mala f 2 and Mala f 3. M. pachydermatis contains Mala s 1, Mala f 4, and Mala s 5-Mala s 8. M. restricta and M. slooffiae possessed Mala f 4 and Mala s 6. M. furfur was seen to possess Mala f 2-Mala f 4 as well as Mala s 5-Mala s 7. Our data from reverse-transcriptase PCR showed a more species-specific pattern of amplification. M. furfur evidenced expression of Mala f 2-Mala f 4. M. globosa and M. obtusa appeared to express only Mala s 6. M. pachydermatis expressed Mala f 4, Mala s 6, and Mala s 8, while M. restricta and M. slooffiae expressed Mala f 4 and Mala s 6. M. sympodialis expressed all the allergens except Mala f 2 and Mala f 3. Different Malassezia species appear to contain both common and species-specific allergen sequences.

Atopy patch test reactions to Malassezia allergens differentiate subgroups of atopic dermatitis patients

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.

Atopic dermatitis and fungi

Atopic dermatitis (AD) is a chronic, itching, inflammatory skin disease which is associated with asthma and/or hay fever and a familial occurrence of these conditions. Genetic factors are important in the development of AD, but the exact hereditary pathway is still unknown. Dry skin and the weakened barrier function in patients with AD is very important for the patient's reactions to irritants and other external trigger factors including microorganisms. The standard treatments are topical corticosteroids, topical immunomodulating agents, and emollients. If AD cannot be controlled by this type of treatment, systemic immunomodulating agents may be used. UVB, UVA, or psoralen-UVA may also be used for widespread severe lesions. However, some patients do not respond to these standard treatment, and then it is important to consider the role of microorganisms, house dust mites or food. The role of the Malassezia yeasts in AD, especially AD located to the head and neck region, is now documented in several papers. There are also several papers indicating the role of Candida as an aggravating factor in AD. Patients with AD also develop chronic dermatophyte infections more easily, and patients with AD and chronic dermatophyte infections may show improvement in their AD when treated with antifungal drugs.

Immunology of diseases associated with Malassezia species

Malassezia species are members of the human cutaneous commensal flora, in addition to causing a wide range of cutaneous and systemic diseases in suitably predisposed individuals. Studies examining cellular and humoral immune responses specific to Malassezia species in patients with Malassezia-associated diseases and healthy controls have generally been unable to define significant differences in their immune response. The use of varied antigenic preparations and strains from different Malassezia classifications may partly be responsible for this, although these problems can now be overcome by using techniques based on recent work defining some important antigens and also a new taxonomy for the genus. The finding that the genus Malassezia is immunomodulatory is important in understanding its ability to cause disease. Stimulation of the reticuloendothelial system and activation of the complement cascade contrasts with its ability to suppress cytokine release and downregulate phagocytic uptake and killing. The lipid-rich layer around the yeast appears to be pivotal in this alteration of phenotype. Defining the nonspecific immune response to Malassezia species and the way in which the organisms modulate it may well be the key to understanding how Malassezia species can exist as both commensals and pathogens.

Serum IgE reactivity to Malassezia furfur extract and recombinant M. furfur allergens in patients with atopic dermatitis

IgE reactivity to the opportunistic yeast Malassezia furfur can be found in patients with atopic dermatitis (AD). We have previously cloned and expressed 6 recombinant allergens (rMal f 1, rMal f 5-9) from M. furfur. In the present study, we used ImmunoCAP to investigate whether these rMal f allergens can be useful in the diagnosis of M. furfur-associated AD compared with the M. furfur extract. A total of 156 adult patients with a clinical diagnosis of AD participated in the study. Sixty-four percent had increased total serum IgE levels, 79% had specific IgE antibodies to common inhalant allergens and 47% had IgE antibodies to M. furfur extract. IgE antibodies to any of the rMal f allergens were detected among 86 (55%) of the patients, 14 (16%) of whom did not react to the M. furfur extract. Any individual rMal f allergen detected between 32% and 89% of the patients ImmunoCAP-positive to the M. furfur extract, with the highest sensitivity for rMal f 9. Therefore, a couple of individual rMal f allergens can improve the diagnosis of M. furfur-associated IgE allergies in patients with AD.

Antigenic components of Malassezia species for immunoglobulin E antibodies in sera of patients with atopic dermatitis

Antigenic components of Malassezia furfur, M. globosa, M. restricta, M. slooffiae, and M. sympodialis were studied for immunoglobulin E antibodies in sera of patients with atopic dermatitis (AD). Antigenic components were extracted from Malassezia cells by treatment with beta-mercaptoethanol, referred to as 2-ME extract. CBB staining and lectin blots using Con A, LCA, PHA-E4, PNA or RCA120 showed that the 2-ME extracts contained several species-dependent components that differed quantitatively and qualitatively among the Malassezia species at the protein level. In the Western blot with the 2-ME extracts, of 54 sera of the patients with AD (54 patients), the patients' IgE antibodies most frequently recognized components showing molecular weights of 43-46 kDa for M. slooffiae, 12-22 kDa for M. sympodialis, 35-40 kDa for M. restricta, 45-50 kDa for M. globosa, and of 67-72 kDa for M. furfur, respectively. In the correlative study, in which the total band intensities generated for each extract in Western blot were compared among the Malassezia species, the intensity for M. globosa was well correlated with that for M. sympodialis (r=0.756). In the Western blot inhibition test, the 2-ME extract of M. globosa partially inhibited the reaction of the antigenic components of other Malassezia species with the patient's IgE antibodies. These results indicated that Malassezia species contained both species-specific and common antigenic components at the IgE antibody level.

The relevance of skin prick tests for Pityrosporum ovale in patients with head and neck dermatitis

BACKGROUND

Patients with atopic dermatitis often develop immunoglobulin E antibodies against the yeast Pityrosporum ovale. This organism may produce positive skin prick reactions in a higher rate in patients with atopic dermatitis of the head, scalp, and neck region.

METHODS

We investigated whether positive prick tests to P. ovale were associated with a specific localization in the head and neck region. A total of 589 consecutive patients were prick tested with a P. ovale extract from ALK Abelló.

RESULTS

Thirty-seven patients (6.3%) showed a positive reaction to the P. ovale extract. We could not find significant differences in the localizations of the dermatitis and the pattern of reaction to the tested intracutaneous allergens between the 37 patients positive to P. ovale and the control group of 55 subjects with negative reactions. In a subgroup, we found an elevated level of P. ovale-specific IgE in 100.0% of the patients with head and neck dermatitis, compared with 13.6% in the atopic dermatitis patients with lesions in any other localization.

CONCLUSIONS

Our results clearly show that P. ovale-specific IgE is strongly related to the head and neck localization of atopic dermatitis, but RAST seems more sensitive than a prick test with the extract we used.

Cloning, characterization and expression of complete coding sequences of three IgE binding Malassezia furfur allergens, Mal f 7, Mal f 8 and Mal f 9

Malassezia furfur, formerly known as Pityrosporum orbiculare or P. ovale, is a yeast that colonizes human skin. Normally, this yeast is nonpathogenic but under the influence of predisposing factors it may induce IgE reactivity in patients with atopic dermatitis. Approximately 40-65% of atopic dermatitis patients have IgE antibodies and/or skin reactivity against M. furfur and a higher T-cell response against this yeast is found in atopic dermatitis patients than in healthy individuals. By making a cDNA library displayed on a phage surface, we previously cloned five different IgE-binding proteins, Mal f 5, Mal f 6, MF 7, MF 8 and MF 9, from this yeast. The cDNAs encoding these allergens were sequenced and expressed in Escherichia coli. The sequences of MF 7, MF 8 and MF 9 were not full length (missing their 5'-ends) giving only partial gene products. To obtain complete cDNA sequences, we performed RACE-PCR to amplify the 5'-ends of each cDNA. These PCR products were sequenced and analyzed. The coding sequences of Mal f 7, Mal f 8 and Mal f 9 encode proteins with ORFs of 141 (16.2 kDa), 179 (19.2 kDa) and 126 (14.0 kDa) amino-acid residues, respectively. None of the putative proteins showed significant sequence homology with other known proteins in the searched database. The proteins encoded by the complete cDNA sequences were expressed in E. coli as recombinant proteins. Immunoblotting and radioallergosorbant test data showed that all of the expressed recombinant proteins have the ability to bind serum IgE from atopic dermatitis patients and furthermore, the M. furfur extract could specifically inhibit this IgE binding.

Selective cloning of allergens from the skin colonizing yeast Malassezia furfur by phage surface display technology

The yeast Malassezia furfur, also known as Pityrosporum orbiculare (ovale), is part of the normal microflora of the human skin but has also been associated with different skin diseases including atopic dermatitis. More than 50% of atopic dermatitis patients have positive skin test and specific IgE to M. furfur extracts; however, the pathophysiologic role of these IgE-mediated reactions in the development of the disease remains unknown. The yeast is able to produce a wide panel of IgE-binding proteins, variably recognized by sera of individual patients. In order to assess the contribution of individual components to the disease, highly pure allergen preparations are required. We have cloned M. furfur allergens from a cDNA library displayed on the phage surface, sequenced the inserts and produced recombinant proteins in Escherichia coli. Phage displaying IgE-binding proteins were selectively enriched from the library using IgE from a M. furfur-sensitized atopic dermatitis patient as a ligand. We were able to identify five different inserts coding for IgE-binding polypeptides. Three of the sequenced cDNA encode incomplete gene products with molecular masses of 21.3 kDa (MF 7), 14.4 kDa (MF 8), and 9.7 kDa (MF 9), respectively, having no sequence similarity to known proteins. The other two cDNA encode allergens of 18.2 kDa (Mal f 5) and 17.2 kDa (Mal f 6). Mal f 5 shows significant homology to M. furfur allergens Mal f 2, Mal f 3 and an Aspergillus fumigatus allergen Asp f 3. Mal f 6 has significant homology with cyclophilin. All of the recombinant polypeptides were capable of binding serum IgE from atopic dermatitis patients in immunoblotting experiments. The availability of pure recombinant M. furfur allergens will allow the careful investigation of the role of IgE-binding proteins in atopic dermatitis.

Immunologic characterization of natural and recombinant Mal f 1 yeast allergen

BACKGROUND

Individuals with atopic dermatitis (AD) often have IgE antibodies against protein components of Malassezia furfur. The cDNA encoding one of these proteins (Mal f 1) has recently been cloned and sequenced.

OBJECTIVE

We sought to express recombinant Mal f 1 (rMal f 1) allergen in large quantities by using different expression systems. The primary aim was to characterize the IgE-binding properties of rMal f 1 in comparison with its natural counterpart in M furfur extract.

METHODS

We have expressed and purified Mal f 1 from prokaryotic (Escherichia coli) and eukaryotic cells (baculovirus-infected insect cells). The rMal f 1 produced in both systems has been tested for the ability to be recognized by IgE from patients with specific serum IgE to M furfur by using immunoblotting and the Pharmacia CAP System RAST FEIA.

RESULTS

Sixty-one percent of sera from 95 patients showed positive RAST responses to the rMal f 1 produced in the baculovirus expression system and 43% to the E coli -produced rMal f 1. Both the E coli - and baculovirus-produced proteins can specifically inhibit IgE binding to a 36-kd protein band (Mal f 1) in immunoblotting, indicating that the recombinant proteins contain the majority, if not all, the IgE-binding epitopes of Mal f 1. Recombinant Mal f 1 is able to release histamine from basophils of an atopic individual.

CONCLUSION

We have expressed and purified rMal f 1, which can bind IgE in a way resembling natural Mal f 1. The ability to produce recombinant allergens with similar properties to their native counterparts has many potential uses, such as accurately diagnosing causes of IgE-mediated allergy.

Two-dimensional electrophoresis of Malassezia allergens for atopic dermatitis and isolation of Mal f 4 homologs with mitochondrial malate dehydrogenase

The yeast Malassezia furfur is a natural inhabitant of the human skin microflora that induces an allergic reaction in atopic dermatitis. To identify allergens of M. furfur, we separated a crude preparation of M. furfur antigens as discrete spots by 2-D PAGE and detected IgE-binding proteins using sera of atopic dermatitis patients. We identified the known allergens, Mal f 2 and Mal f 3, and determined N-terminal amino acid sequences of six new IgE-binding proteins including Mal f 4. The cDNA and genomic DNA encoding Mal f 4 were cloned and sequenced. The gene was mitochondrial malate dehydrogenase and encoded Mal f 4 composed of 315 amino acids and a signal sequence of 27 amino acids. We purified Mal f 4, which had a molecular mass of 35 kDa from a membrane fraction of a lysate of cultured cells. Thirty of 36 M. furfur-allergic atopic dermatitis patients (83.3%) had elevated serum levels of IgE to purified Mal f 4, indicating that Mal f 4 is a major allergen. There was a significant correlation of the Phadebas RAST unit values of Mal f 4 and the crude antigen, but not between Mal f 4 and the known allergen Mal f 2.

Seborrhoeic dermatitis is not caused by an altered immune response to Malassezia yeast

The immune response of patients with seborrhoeic dermatitis and healthy age- and sex-matched controls was examined to test the hypothesis that an inadequate or inappropriate immune response to Malassezia yeast leads to seborrhoeic dermatitis. Antibody responses were examined using enzyme-linked immunosorbent assays (ELISAs) and Western blots and lymphocyte responses using lymphocyte proliferation assays. The level of IgG and IgM specific for whole yeast cells or extracted proteins of two isolates of M. furfur was tested in ELISA. A wide range of antibody levels was found but the patient and control groups were indistinguishable (n = 19), and the groups could not be distinguished by the pattern of Malassezia proteins recognized by their sera in Western blots. The average affinity of the subjects' antibodies specific for Malassezia cells or proteins was measured using ammonium thiocyanate dissociation. Most of the sera had moderate affinities corresponding to 50% dissociation at thiocyanate concentrations of 0.5-1.0 mol/L. There was no difference between patients and matched controls. The proliferation of the patients' lymphocytes in response to a number of M. furfur cell preparations was measured: whole cells, cytoplasmic proteins, cell walls, soluble molecules extracted from the cell walls using sonication, and a commercial preparation. There was a wide range of responses between individuals, but there was no difference between the three groups: patients with seborrhoeic dermatitis (n = 16), healthy controls (n = 16) and a group suffering from other inflammatory skin conditions (n = 15). The results do not support the hypothesis that an inadequate immune response to Malassezia yeast could lead to seborrhoeic dermatitis. Other possible pathological mechanisms include toxin production or lipase activity.

The complete cDNA sequence and expression of the first major allergenic protein of Malassezia furfur, Mal f 1

For the first time the complete cDNA encoding a major allergen and novel protein of the yeast Malassezia furfur, Mal f 1, has been sequenced and expressed. The amino acid sequences of nine tryptic peptides of the protein were determined. Oligonucleotides were designed from these amino acid sequences. The cDNA sequence was obtained by hybridizing these primers to mRNA and enhancement by reverse-transcriptase PCR techniques. The cDNA is 1176 bp in length. It shows an open reading frame of 1050 bp coding for a protein of 38178 Da and a deduced amino acid sequence containing 350 residues. The hydropathy plot and the tryptic digest indicate that the first 22 amino acids represent a leader sequence determining a mature protein of 35 988 Da. The complete encoding cDNA was expressed as a maltose-binding protein fusion protein in Escherichia coli. The recombinant fusion protein reacted with our specific monoclonal antibody and with IgE from patients with atopic dermatitis.