Objective To investigate the changes of interleukin-18 (IL-18), interleukin 18 binding protein (IL-18BP) and interleukin 18 receptor (IL-18R) expressions in eosinophil-enriched cells from asthmatic patients, and study the correlations among them. Methods Peripheral venous blood from asthmatic patients and normal subjects were collected and stimulated with the extracts of Artemisia pollen, dust mite, and Platanus pollen. The expressions of IL-18, IL-18BP and IL-18R in eosinophil-enriched blood cells were detected by flow cytometry, and the correlations among them were analyzed. Results The proportion of IL-18+ cells in eosinophil-enriched cells from asthmatic patients increased 15-fold compared with normal subjects. The proportion of IL-18+ cells increased about 1.3-fold and 1.5-fold in eosinophil-enriched cells from asthmatic patients whose blood was stimulated with dust mite and Platanus pollen extracts, respectively. The average fluorescence intensity (MFI) of IL-18BP+ cells increased about 1.5-fold and the proportion of IL-18R+ cells increased about 2-fold in eosinophil-enriched cells from asthmatic patients' blood stimulated with Platanus pollen extracts. In addition, the expressions of IL-18BP+ cells and IL-18R+ cells showed a positive correlation (r=0.639) in eosinophil-enriched cells from asthmatic patients stimulated with allergens. However, the expressions of IL-18, IL-18BP and IL-18R in eosinophil-enriched cells did not obviously change in normal subjects. Conclusion IL-18, IL-18R and IL-18BP expressed in eosinophils may be involved in the inflammatory reaction of asthma.