Elevated soluble interleukin-2 receptors in young healthy cigarette smokers: lack of association with atopy or airways hyperresponsiveness.

To study the relationship of atopy and nonspecific airways hyperresponsiveness to circulating levels of soluble interleukin-2 receptors (sIL-2R), we measured serum sIL-2R concentrations in 40 young, healthy smokers and non-smokers. Levels of sIL-2R were significantly higher in current smokers than in nonsmokers (median sIL-2R levels 605 vs. 398 U/ml, respectively; p less than 0.05). Serum sIL-2R levels were not related to nonspecific airways hyperresponsiveness to methacholine, allergy skin test reactivity, doctor-diagnosed asthma or hay fever, or respiratory symptoms of wheeze. Among current smokers, a trend toward higher sIL-2R levels (not statistically significant) was observed among subjects reporting symptoms of phlegm production. The increase in sIL-2R levels associated with cigarette smoking was similar in magnitude to that reported for immune-mediated conditions such as collagen vascular diseases and eczema. These data confirm that cigarette smoking is an important determinant of sIL-2R level, even among young healthy subjects. This effect does not appear to be related to atopic status or bronchial responsiveness. Among cigarette smokers, sIL-2R level may be related to the presence of conditions associated with phlegm production.