\[Abstract\]ObjectiveTo examine the serum level of IL-22 in asthmatic patients and the expression of IL-22R1 in human airway epithelial cells, human airway smooth muscle cells, and lung fibroblasts, so as to explore the target cells of IL-22. MethodsThe serum levels of IL-22 and IL-17 in 36 asthmatic patients and 20 normal control subjects were measured by enzyme-linked immunosorbent assay (ELISA). And lung function of the asthmatic patients was assessed by Gaeger spirometry. According to the values of FEV1/FVC and FEV1%, the patients were divided into two groups: bronchodilation test positive group (19 patients) and bronchial provocation test positive group (17 patients). The expression of IL-22R1 mRNA in human airway epithelial cells, human airway smooth muscle cells, and lung fibroblasts was examined using real-time PCR, and IL-22R1 protein expression was detected by immunofluorescence staining and Western blotting analysis. ResultsThere was no significant difference in serum IL-22 and IL-17 levels between the asthmatic patients and normal controls. The serum IL-22 and IL-17 levels in asthmatic patients positive for bronchodilation test was significantly higher than those positive for bronchial provocation test(P<0.05). IL-22R1 mRNA and protein were detected in all the 3 types of cells. ConclusionIL-22 may be involved in the pathogenesis of asthma, and human airway epithelial cells, human airway smooth muscle cells, and lung fibroblasts may all be the target cells of IL-22.