Soluble CD163 Levels and CD163+CD14+ Monocyte/Macrophage Counts in Patients with Asthma

Background: CD163-expressing macrophages are involved in the inflammatory response in asthma. Objective: To assess sputum and serum soluble CD163 (sCD163) and cytokine levels in patients with asthma. Further discussed was the difference between sCD163 and other classic inflammatory mediators. Methods: Sputum was successfully induced in asthma patients (n=85) and healthy controls (n=21). Interleukin (IL)-4, IL-5, IL-1β, IL-8, IL-9, IL-6, and sCD163 levels in sputum were measured. CD163+ monocytes in blood were evaluated using flow cytometry. Results: Sputum sCD163 level significantly increased in asthma (median: 22.4 pg/ml; IQR, 11.52-42.91), unlike healthy controls (10.54 pg/ml;9.85-23.5; P<0.001). Sputum sCD163 (P=0.020) and serum sCD163 (P=0.032) levels were significantly higher in patients with severe asthma compared to those with mild/moderate asthma. Percentage of CD163+ monocytes in patients with asthma was significantly lower than the controls (P<0.001). Conclusion: Increased sCD163 levels in sputum are associated with the impairment of lung function.