ABSTRACT
The respiratory tract is regularly exposed to inhaled micro-organisms. In normal individuals, this rarely results in prolonged lower respiratory illness, but in those with asthma, exacerbations of airway obstruction may result. Epidemiological studies strongly suggest that viral infection is a common cause of significant exacerbations in both children and adults with asthma, as discussed fully elsewhere in this book. Inflammatory and immune responses, which are now believed to be in large part governed by the lung’s complex cytokine system, play key roles in producing the clinical features of both asthma and acute viral infection. This chapter will provide an overview of the cytokine network in the lung, how it is altered in asthma, and how viral respiratory infection may further affect cytokine balance to produce exacerbations of airways obstruction.
