• Dominique M A Bullens, Els Truyen, Liesbeth Coteur, Ellen Dilissen, Peter W Hellings, Lieven J Dupont, and Jan L Ceuppens.
• Department of Experimental Medicine, Clinical Immunology, Katholieke Universiteit Leuven, (KULeuven), Leuven, Belgium. Dominique.Bullens@med.kuleuven.be
• Resp Res. 2006 Jan 1;7:135.

BackgroundThe role of Th2 cells (producing interleukin (IL-)4, IL-5 and IL-13) in allergic asthma is well-defined. A distinct proinflammatory T cell lineage has recently been identified, called Th17 cells, producing IL-17A, a cytokine that induces CXCL8 (IL-8) and recruits neutrophils. Neutrophilic infiltration in the airways is prominent in severe asthma exacerbations and may contribute to airway gland hypersecretion, bronchial hyper-reactivity and airway wall remodelling in asthma.Aimto study the production of IL-17 in asthmatic airways at the mRNA level, and to correlate this with IL-8 mRNA, neutrophilic inflammation and asthma severity.MethodsWe obtained airway cells by sputum induction from healthy individuals (n = 15) and from asthmatic patients (n = 39). Neutrophils were counted on cytospins and IL-17A and IL-8 mRNA expression was quantified by real-time RT-PCR (n = 11 controls and 33 asthmatics).ResultsSputum IL-17A and IL-8 mRNA levels are significantly elevated in asthma patients compared to healthy controls. IL-17 mRNA levels are significantly correlated with CD3gamma mRNA levels in asthmatic patients and mRNA levels of IL-17A and IL-8 correlated with each other and with sputum neutrophil counts. High sputum IL-8 and IL-17A mRNA levels were also found in moderate-to-severe (persistent) asthmatics on inhaled steroid treatment.ConclusionThe data suggest that Th17 cell infiltration in asthmatic airways links T cell activity with neutrophilic inflammation in asthma.

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