Functional expression of IL-9 receptor by human neutrophils from asthmatic donors: Role in IL-8 release

Human polymorphonuclear neutrophils (PMN's) express surface receptors for various inflammatory mediators, including IgE and IL-4, Recently, the IL-9R locus has been genetically linked to asthma and bronchial hyperresponsiveness in humans. In this study, we evaluated expression of the IL-9R and the effect of IL-9 on human PMNs. RT-PCR analysis showed the presence of IL-9R alpha -chain mRNA in PMN RNA preparations from asthmatic patients. Wing FAGS analysis, surface expression of IL-9R alpha was detected on PMN's freshly isolated from asthmatics, and to a lesser extent on normal controls, In addition, protein expression of IL-9R alpha was also detected in peripheral blood and bronchoalveolar lavage PMNs. Furthermore, functional studies showed that IL-9 stimulation of PMNs results in the release of IL-8 in a concentration-dependent manner. The anti-IL-9 neutralizing Ab suppressed this effect, hut had no effect on GM-CSF-induced IL-X release from PMNs, Taken together, these findings suggest a novel role for PMNs in allergic disease through the expression and activation of the IL-9R.