METHODS: The CRTH2 expression on T cells in whole blood were analyzed using flow cytometry. %predicted PEFR, asthma control test(ACT), asthma quality of life questionnaire and absolute eosinophil counts were investigated to find the correlation with CRTH2 expression level.
RESULTS: 46 asthma patients(11 eosinophilic asthma patients, 30 non-eosinophilic allergic asthma patients, and 5 non-eosinophilic non-allergic asthma patients) and 11 healthy subjects were enrolled. Asthma patients had higher level of CRTH2+ Treg cells of total CD3+ cells(0.12%±0.09 and 0.04%±0.03, p=0.001) and higher frequency of CRTH2 expression on Tc than healthy(1.04%±0.51 and 0.60%±0.50, p=0.006). No significant difference of CRTH2 expression on Th cells was observed. In subgroup analysis, we found the frequency of CRTH2 expression on Treg cells in eosinophilic asthma patients (0.19%±0.14) was significantly higher than non-eosinophilic allergic asthma patients(0.10%±0.06) and non-eosinophilic non-allergic asthma patients(0.06%±0.03). The frequency of CRTH2 expression on Treg cells among asthma patients had negative correlation with ACT scores(r=-0.29, p=0.04) whereas positive correlation with absolute eosinophil counts(r=0.39, p=0.007).
CONCLUSIONS: Elevated levels of peripheral CRTH2 expression on Treg and Tc cells are key features in asthma. The different correlation of CRTH2+ Treg cells with asthma control and eosinophil counts elucidated as potential targeted therapy for future asthmatic treatment.