Sputum inflammatory profile before and after specific inhalation challenge in individuals with suspected occupational asthma.
BACKGROUND
The aim of this study was to establish the sputum inflammatory profile and changes in levels of leukotriene B₄ (LTB₄) and a panel of Th1/Th2 cytokines in subjects with suspected occupational asthma (OA) following specific inhalation challenge (SIC) to high-molecular-weight (HMW) and low-molecular-weight (LMW) agents.


METHODS
Fifty-one consecutive subjects undergoing SIC for suspected OA were enrolled. Sputum induction was performed the day before and 24 h after exposure to the offending agent. Total and differential cell counts were assessed. LTB₄ and a 10 Th1/Th2 cytokines were measured in sputum supernatant.


RESULTS
Thirty-four patients tested positive to SIC and were diagnosed with OA (in 10 due to HMW agents and in 24 to LMW agents). SIC was negative in 17 subjects. As compared to baseline an increase was found in the percentage of sputum eosinophils and neutrophils, and in IL-10 concentration after SIC (p = 0.0078, p = 0.0195, and p = 0.046, respectively), and a decrease was seen in LTB₄ level (p = 0.0078) in patients with OA due to HMW agents. An increase in the percentage of sputum neutrophils after SIC (p = 0.0040) was observed in subjects without OA exposed to LMW agents. IL-8 levels after SIC were higher in patients without OA compared with patients with OA (p = 0.0146).


CONCLUSIONS
When conducting airway inflammation studies in OA, patients should be divided according to the causal agent (HMW or LMW). In OA patients exposed to HMW agents, an increase in the number of neutrophils can be found in parallel to the increase of eosinophils, although this does not contradict an IgE-mediated mechanism. Exposure to LMW agents can result in increased neutrophilic inflammation in patients with airway diseases unrelated to OA. There is variability in the responses observed in patients with OA exposed to LMW agents.
Servei de Pneumologia, Hospital Universitari Vall d'Hebron, Barcelona, Spain ; CIBER Enfermedades Respiratorias (Ciberes), Barcelona, Spain ; Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
Sara
S
Sánchez-Vidaurre
María-Jesús
MJ
Cruz
Susana
S
Gómez-Ollés
Ferran
F
Morell
Xavier
X
Muñoz
D000280:Administration, Inhalation; D000293:Adolescent; D000328:Adult; D059366:Asthma, Occupational / Q000175:diagnosis / Q000276:immunology / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism*; D004804:Eosinophils / Q000276:immunology; D005260:Female; D006801:Humans; D007958:Leukocyte Count; D007975:Leukotriene B4 / Q000378:metabolism*; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage; D008875:Middle Aged; D008970:Molecular Weight; D009504:Neutrophils / Q000276:immunology; D013183:Sputum / Q000276:immunology / Q000378:metabolism*; D018417:Th1 Cells / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology / Q000378:metabolism; D055815:Young Adult
D015415:Biomarkers; D016207:Cytokines; D016210:Methacholine Chloride; D007975:Leukotriene B4