Phenotype of IL-16-producing cells in bronchial mucosa: evidence for the human eosinophil and mast cell as cellular sources of IL-16 in asthma.
BACKGROUND
We have previously shown increased expression of the CD4+ cell chemoattractant interleukin (IL)-16 in bronchial biopsies of atopic asthmatic subjects compared to normal controls. IL-16 immunoreactive cells were identified as both epithelial cells and non-epithelial inflammatory cells. The aim of this study was to characterize and compare the phenotype of non-epithelial inflammatory cells that express IL-16 immunoreactivity in bronchial biopsies from non-atopic normal controls and atopic asthmatic subjects.


METHODS
Sections from endobronchial biopsies obtained from non-atopic normal controls and atopic asthmatics were processed for double immunocytochemistry. IL-16 immunoreactivity was assessed using a polyclonal anti-IL-16 antibody and the avidin-biotin complex-diaminobenzidine method. The phenotype of IL-16 immunoreactive cells was assessed using anti-CD3, anti-MBP, anti-tryptase and anti-CD68 mAbs and the alkaline phosphatase complex-Fast Red method.


RESULTS
In normal subjects, the majority of IL-16 immunoreactive cells were CD3+ T cells (71.1+/-10.3%) and CD68+ macrophages (22.4+/-8.1%). IL-16 immunoreactivity coexpressed with tryptase+ mast cells in 4 of 7 normal subjects whereas IL-16 immunoreactivity coexpressed with MBP+ eosinophils in only 1 normal subject. In atopic asthmatic subjects, IL-16 immunoreactive cells were mainly CD3+ T cells (60.8+/-8.7%) and MPB+ eosinophils (16.8+/-8.2%). IL-16 immunoreactivity also coexpressed with tryptase+ mast cells (10.6+/-4.0%) in all asthmatic subjects. The number of IL-16 immunoreactive cells that coexpressed MBP was higher in asthmatic subjects compared to normal controls (p = 0.003).


CONCLUSIONS
Our data show that T cells are the major non-epithelial cellular source of IL-16 in normal and asthmatic airways. Eosinophils and mast cells comprised other potential cellular sources of IL-16 in asthmatic airways.
Ste-Justine Hospital, University of Montreal, Montreal, Canada. labergso@magellan.umontreal.ca
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S
Laberge
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Pinsonneault
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Ernst
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Olivenstein
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Ghaffar
D M
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Center
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Hamid
D000328:Adult; D001249:Asthma / Q000235:genetics / Q000473:pathology*; D001706:Biopsy; D001980:Bronchi / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000473:pathology; D019410:Interleukin-16 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008297:Male; D009092:Mucous Membrane / Q000378:metabolism; D010641:Phenotype
D019410:Interleukin-16