Interleukin-10 is a natural suppressor of cytokine production and inflammation in a murine model of allergic bronchopulmonary aspergillosis

We have used interleukin-10 (IL-10) gene knockout mice (IL-10(-/-)) to examine the role of endogenous IL-10 in allergic lung responses to Aspergillus fumigatus Ag. In vitro restimulated lung cells from sensitized IL-10(-/-) mice produced exaggerated amounts of IL-4, IL-5, and interferon-gamma (IFN-gamma) compared with wild-type (WT) lung cells. In vivo, the significance of IL-10 in regulating responses to repeated A. fumigatus inhalation was strikingly revealed in IL-10(-/-) outbreed mice that had a 50-60% mortality rate, while mortality was rare in similarly treated WT mice. Furthermore, IL-10(-/-) outbred mice exhibited exaggerated airway inflammation and heightened levels of IL-5 and IFN-gamma in bronchoalveolar lavage (BAL) fluids. In contrast, the magnitude of the allergic lung response was similar in intranasally (i.n.) sensitized IL-10(-/-) and wild-type mice from a different strain (C57BL/6). Using a different route of priming (intraperitoneal) followed by one i.n. challenge we found that IL-10(-/-) C57BL/6 mice had heightened eosinophilic airway inflammation, BAL-IL-5 levels, and numbers of alpha beta T cells in the lung tissues compared with WT mice. We conclude that IL-10 can suppress inflammatory Th2-like lung responses as well as Th1-like responses given the constraints of genetic background and route of priming.