Publications

Although chlorine gas is a common irritant exposure, little is known about airway responses to chlorine inhalation among persons with baseline airway hyperreactivity. We wished to determine whether such persons manifest an exaggerated response to chlorine compared with normal subjects. We studied 10 subjects, five with and five without airway hyperresponsiveness (HR) after exposure to 1.0 ppm chlorine and five persons, all with HR, to 0.4 ppm chlorine. After 1.0 ppm inhalation, there was a significant (p < 0.05) fall (mean +/- SE) in FEV1 immediately following exposure among normal (-180 +/- 37 mL) and HR subjects (-520 +/- 171 mL). The fall was greater among the HR compared with the normal subjects (p = 0.04). Specific airway resistance (Sraw) increased to a greater degree among the HR group compared with normal subjects (p = 0.04). Among all subjects (n = 10), the proportional change in FEV1 after 1.0 ppm chlorine correlated with baseline reactivity (Spearman rank correlation r = 0.64, p < 0.05). At 24-h follow-up, there were no significant chlorine-related pulmonary function deficits. After 0.4 ppm chlorine inhalation, there was no significant pulmonary function effect. These data indicated that persons with hyperreactive airways manifest an exaggerated airway response to chlorine at 1.0 ppm. This suggests that when large numbers of persons are exposed to chlorine, a susceptible subpopulation may acutely respond with a greater decrement in pulmonary function.

The specific signal transduction function of the gamma c subunit in the interleukin (IL) 2, IL-4, IL-7, IL-9, and IL-15 receptor complexes remains undefined. The present structure-function analyses demonstrated that the entire cytoplasmic tail of gamma c could be functionally replaced in the IL-2 receptor (IL-2R) signaling complex by a severely truncated erythropoietin receptor cytoplasmic domain lacking tyrosine residues. Heterodimerization of IL-2R beta with either gamma c or the truncated erythropoietin receptor chain led to an array of specific signals normally derived from the native IL-2R despite the substitution of Janus kinase JAK2 for JAK3 in the receptor complex. These findings thus suggest a model in which the gamma c subunit serves as a common and generic "trigger" chain by providing a nonspecific Janus kinase for signaling program initiation, while signal specificity is determined by the unique "driver" subunit in each of the gamma c- containing receptor complexes. Furthermore, these results may have important functional implications for the asymmetric design of many cytokine receptor complexes and the evolutionary design of receptor subfamilies that share common trigger or driver subunits.