title: Atopy patch test reactions to Malassezia allergens differentiate subgroups of atopic dermatitis patients.
abstract: BACKGROUND
  The yeast Malassezia is considered to be one of the factors that can contribute to atopic dermatitis (AD).
  
  
  OBJECTIVE
  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.
authors.affiliation: Department of Medicine, Unit of Clinical Allergy Research and Dermatology and Venereology, Karolinska Institutet and Hospital, SE-171 76 Stockholm, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Johansson
authors.forename: M H
authors.initials: MH
authors.lastname: Sandström
authors.forename: J
authors.initials: J
authors.lastname: Bartosik
authors.forename: T
authors.initials: T
authors.lastname: Särnhult
authors.forename: J
authors.initials: J
authors.lastname: Christiansen
authors.forename: A
authors.initials: A
authors.lastname: Zargari
authors.forename: O
authors.initials: O
authors.lastname: Bäck
authors.forename: C F
authors.initials: CF
authors.lastname: Wahlgren
authors.forename: J
authors.initials: J
authors.lastname: Faergemann
authors.forename: A
authors.initials: A
authors.lastname: Scheynius
authors.forename: M
authors.initials: M
authors.lastname: Tengvall Linder
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D016022:Case-Control Studies; D003876:Dermatitis, Atopic / Q000175:diagnosis / Q000276:immunology*; D012628:Dermatitis, Seborrheic / Q000175:diagnosis / Q000276:immunology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D008290:Malassezia / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010328:Patch Tests / Q000379:methods*; D011994:Recombinant Proteins / Q000276:immunology; D012720:Severity of Illness Index
chemical_list: D000485:Allergens; D011994:Recombinant Proteins; D007073:Immunoglobulin E