Identification of an obeche (Triplochiton scleroxylon) wood allergen as a class I chitinase.
BACKGROUND
Wood dust is known to cause allergic occupational asthma and obeche (Triplochiton scleroxylon) is a prominent exponent in this field. However, the knowledge about wood allergens is still limited. The aim of this study was to identify and characterize obeche wood allergens.


METHODS
Obeche extracts were prepared from freshly ground in comparison to 7 years stored wood dust and investigated by Sodium dodecyl sulfate-polyacrylamid gel electrophoresis, enzyme-linked allergosorbent test and immunoglobulin (Ig)E-immunoblot. Allergens were detected by specific IgE of seven obeche allergic patients' sera and protein analysis was performed by mass spectrometry. Cross-reactivity was demonstrated by ImmunoCAP-inhibition with sera of seven obeche and four latex-allergic patients.


RESULTS
Obeche extracts showed different protein pattern and IgE-binding capacities depend on the age of the wood dust. A 38 kDa protein was identified as major obeche wood allergen, detected by six of seven (85%) obeche allergic patients' sera and was entitled as Trip s 1. Trip s 1 is homologous to plant class I chitinases and exhibited enzyme activity demonstrated by chitinolysis. Co-recognition or cross-reactivity of Trip s 1 according to structural similarity was seen in sera of latex allergic patients. IgE inhibition studies with obeche as solid phase and Trip s 1 and latex hevein as inhibitor demonstrated that Trip s 1 was a more effective inhibitor in obeche as well as in latex allergic patients' sera.


CONCLUSIONS
Trip s 1 is a new obeche wood allergen of the plant class I chitinase family. This finding may explain the dominant role of obeche in sensitization against wood dust.
Kespohl
S
S
Research Institute for Occupational Medicine of the Berufsgenossenschaften (BGFA), Institute of the Ruhr-University Bochum, Germany.
Sander
I
I
Merget
R
R
Petersen
A
A
Meyer
H E
HE
Sickmann
A
A
Bruening
T
T
Raulf-Heimsoth
M
M
D000328:Adult; D000485:Allergens / Q000009:adverse effects / Q000737:chemistry / Q000276:immunology*; D001249:Asthma / Q000097:blood / Q000209:etiology; D002686:Chitin / Q000378:metabolism; D002688:Chitinases / Q000737:chemistry / Q000276:immunology*; D003429:Cross Reactions; D004391:Dust / Q000032:analysis; D006801:Humans; D007106:Immune Sera; D007073:Immunoglobulin E / Q000097:blood; D020315:Latex Hypersensitivity / Q000276:immunology; D019660:Malvaceae; D008875:Middle Aged; D008970:Molecular Weight; D009784:Occupational Diseases / Q000097:blood / Q000209:etiology; D035261:Plant Components, Aerial / Q000276:immunology; D010936:Plant Extracts / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D014934:Wood
D000485:Allergens; D004391:Dust; D007106:Immune Sera; D010936:Plant Extracts; D010940:Plant Proteins; D002686:Chitin; D007073:Immunoglobulin E; D002688:Chitinases; C119825:chitinase C