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Positive atopy patch test reactions to Pityrosporum orbiculare in atopic dermatitis patients
M Tengvall Linder1, C Johansson, A Scheynius
1Department of Laboratory Medicine, Karolinska Institute and Hospital, Stockholm, Sweden.
Background:
Pityrosporum orbiculare, although a part of our normal cutaneous microflora, can cause skin infections and induce specific immunoglobulin (Ig) E antibodies in atopic dermatitis patients. P. orbiculare is therefore considered to be one of the trigger factors for atopic dermatitis.
Objective:
To investigate if P. orbiculare can induce an eczematous reaction in atopic dermatitis patients, seborrhoeic dermatitis patients and healthy controls.
Methods:
Fifteen atopic dermatitis patients, eight seborrhoeic dermatitis patients and eight healthy controls were patch tested with extract of P. orbiculare on non-lesional, tape-stripped skin of the back. NaCl was used as a negative control. The patch tests were evaluated after 24, 48 and 72 h. Skin biopsies were taken from P. orbiculare patch test sites at 24 h and 72 h, from NaCl patch test sites at 72 h, from non-lesional skin and, in the atopic dermatitis patients, also from lesional skin. The skin biopsies were investigated with immunohistochemical techniques. P. orbiculare-specific IgE in serum was analysed with RAST.
Results:
Specific IgE to P. orbiculare was found in serum from 13/15 atopic dermatitis patients and in eight of them a positive patch test reaction to P. orbiculare was observed, with a maximal reaction at 48 h. Significantly higher serum levels of P. orbiculare-specific IgE were detected in patch test-positive compared with patch test-negative atopic dermatitis patients (P < 0. 01). The seborrhoeic dermatitis patients and healthy controls were RAST and patch test-negative for P. orbiculare. In the patch test-positive atopic dermatitis patients an infiltration of CD4+ T cells and eosinophils was observed at the P. orbiculare patch test sites together with an upregulation of ICAM-1 and HLA-DR expression.
Conclusions:
P. orbiculare can induce an eczematous reaction in sensitized atopic dermatitis patients and may be an important trigger factor in these patients. The P. orbiculare patch test can be of diagnostic value in this subgroup of atopic dermatitis patients.
Insights
Pityrosporum orbiculare can trigger eczematous reactions in atopic dermatitis patients sensitized to the yeast. Patch testing for P. orbiculare may aid in diagnosing this specific subgroup of patients.
Area of Science:
- Dermatology
- Immunology
- Microbiology
Background:
- Pityrosporum orbiculare is a common skin microbe that can cause infections.
- It is implicated as a trigger for atopic dermatitis (AD) by inducing specific IgE antibodies in AD patients.
Purpose of the Study:
- To determine if P. orbiculare can elicit an eczematous reaction in patients with atopic dermatitis, seborrhoeic dermatitis, and in healthy controls.
- To evaluate the diagnostic utility of P. orbiculare patch testing in AD.
Main Methods:
- Patch testing with P. orbiculare extract on 15 AD patients, 8 seborrhoeic dermatitis patients, and 8 controls.
- Skin biopsies and immunohistochemical analysis of test sites.
- Serum analysis for P. orbiculare-specific IgE using RAST.
Main Results:
- 13/15 AD patients had detectable P. orbiculare-specific IgE.
- 8 AD patients showed positive patch test reactions, with peak at 48 hours.
- Patch test-positive AD patients exhibited CD4+ T cell and eosinophil infiltration, with increased ICAM-1 and HLA-DR expression.
Conclusions:
- P. orbiculare can induce eczematous reactions in sensitized AD patients.
- This yeast is a potential trigger factor in specific AD patient subgroups.
- P. orbiculare patch testing may be diagnostically valuable for these patients.
