Factors influencing serum concentrations of soluble interleukin-2 receptor: a general adult population study

Introduction: Measuring soluble interleukin-2 receptor (sIL-2R) might be useful for diagnosis and monitoring of immune-mediated diseases. The study investigated factors associated with serum sIL-2R concentrations in adults. Methods: Serum sIL-2R concentrations were measured in 1499 randomly selected individuals (44.6% male, median age 52 years, range 18-91 years). Lifestyle factors (alcohol consumption, smoking, and physical activity) were assessed by questionnaire. Body mass index and data defining metabolic syndrome were measured in all participants. Atopy was defined by skin tests to aeroallergens. Results: Serum sIL-2R concentrations displayed wide variation (2.5-97.5 percentile range, 209-950 U/mL). A total of 230 (15.3%) individuals showed values higher than the standard reference range (158-623 U/mL). After adjusting for covariates, sIL-2R concentrations increased with age, particularly after 65 years. Serum sIL-2R concentrations were higher in males than in females, were higher in smokers than in never smokers, and were higher in atopic than in non-atopic individuals. Serum sIL-2R concentrations were positively associated with metabolic syndrome, particularly with abdominal obesity, and with a history of ischemic heart disease. Light alcohol drinkers showed lower sIL-2R concentrations than abstainers. Conclusion: Aging, sex, lifestyle factors, atopy, metabolic abnormalities, and ischemic heart disease might influence serum sIL-2R concentrations in adults.