Occupational asthma due to exposure to iroko wood dust.
BACKGROUND
Occupational asthma (OA) from iroko wood has been reported primarily in case reports.


OBJECTIVE
To improve understanding of the pathogenesis of OA induced by iroko wood dust.


METHODS
Three groups of woodworkers were included in this study: 9 workers who had clinically proven OA from iroko; 10 asymptomatic woodworkers; and 10 woodworkers with asthma. All patients underwent the following tests: a skin test with an iroko aqueous extract, specific IgE determination, and an iroko bronchial provocation test (IBPT). An eosinophil count was determined before and after the IBPT, and a methacholine inhalation test was performed after avoidance of exposure to iroko. Patients were asked to monitor their peak expiratory flow rates during a week at work followed by a week's vacation.


RESULTS
In all patients with a personal history predictive of OA from iroko, a reduction of the peak expiratory flow rate and positivity to the IBPT while working with iroko were present. The latter test result showed a dual response, with a decrease in forced expiratory volume in 1 second from 25% to 32% at 10 minutes and a further decrease from 35% to 43% at 8 hours; at 24 hours, the eosinophil count was higher (P = .046). In 4 patients, the intradermal test results with iroko extract were positive, whereas the skin prick test result and the specific IgE determination were negative in all patients. The methacholine test result was also positive. In the control groups, all the test results with iroko extract were negative.


CONCLUSIONS
Our data suggest that OA due to iroko wood may be induced by immunologic mechanisms other than IgE-mediated immediate hypersensitivity reactions.
School and Division of Allergy and Clinical Immunology, University of Messina, Policlinico G Martino Padiglione H, Messina, Italy. luisric@tin.it
Luisa
L
Ricciardi
Roberta
R
Fedele
Salvatore
S
Saitta
Valeria
V
Tigano
Letteria
L
Mazzeo
Olga
O
Fogliani
Domingo
D
Barber
Stefania
S
Isola
D000328:Adult; D000368:Aged; D000395:Air Pollutants, Occupational / Q000009:adverse effects / Q000276:immunology; D000485:Allergens / Q000009:adverse effects / Q000276:immunology; D001249:Asthma / Q000209:etiology*; D001985:Bronchial Provocation Tests; D004391:Dust / Q000276:immunology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000209:etiology; D007073:Immunoglobulin E / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000209:etiology*; D016273:Occupational Exposure; D012882:Skin Tests; D014197:Trees / Q000276:immunology*; D014934:Wood
D000395:Air Pollutants, Occupational; D000485:Allergens; D004391:Dust; D007073:Immunoglobulin E