Abstract: Objective  To evaluate the expression of CXC chemokine ligand 8(CXCL8), CXC chemokine receptor 1(CXCR1), CXC chemokine receptor 2(CXCR2) mRNA in peripheral blood of patients with pulmonary tuberculosis, and to investigate their clinical significance in the diagnosis of pulmonary tuberculosis. 
Methods  Case-control study was performed，and expression levels of CXCL8, its receptor CXCR1 and CXCR2 mRNA were detected by reverse transcription polymerase chain reaction(RT-PCR) in peripheral blood of 125 pulmonary tuberculosis patients, 109 latent infectious patients and 112 healthy controls in this experiment. Pulmonary tuberculosis patients were divided subgroups according to cavity formation：patients with lung cavity vs those without lung cavity. The expression of CXCL8, CXCR1 and CXCR2 mRNA was compared between two groups. All tuberculosis patients were treated with standardized anti-tuberculosis therapy for 6 months, and the dynamic changes of CXCL8, CXCR1 and CXCR2 mRNA were monitored. The value of CXCL8, CXCR1 and CXCR2 in the laboratory diagnosis of pulmonary tuberculosis were analyzed by receiver operator characteristic curve(ROC curve).
Results  The mRNA expression levels of CXCL8, CXCR1 and CXCR2 were significantly higher in peripheral blood in pulmonary tuberculosis group than those in latent tuberculosis group and control group and the differences were statistically significant（P＜0.05）. The mRNA expressions of CXCL8, CXCR1 and CXCR2 in tuberculosis patients with lung cavity group were significantly higher than that in tuberculosis patients without lung cavity group and the differences were statistically significant（P＜0.05）. The mRNA expression levels of CXCL8, CXCR1 and CXCR2 after 3 months treatment were significantly decreased than those before treatment, and the mRNA expression levels of CXCL8, CXCR1 and CXCR2 after 6 months treatment were significantly decreased than those before treatment or after 3 months treatment, and the differences were statistically significant(P＜0.05). The area under ROC curve of CXCL8 in the diagnosis of pulmonary tuberculosis was 0.888, sensitivity was 76.8% and specificity was 90.5%. The area under ROC curve of CXCR1 in the diagnosis of pulmonary tuberculosis was 0.819, sensitivity was 72.8% and specificity was 79.2%. The area under ROC curve of CXCR2 in the diagnosis of pulmonary tuberculosis was 0.756, sensitivity was 59.2% and specificity was 78.8%. 
Conclusion  Chemokine CXCL8 and chemokine receptor CXCR1 and CXCR2 are involved in the anti-tuberculosis immunity of the body. They may be one of the biomarkers for the diagnosis and illness condition assessment of pulmonary tuberculosis.

Key words: tuberculosis, pulmonary, chemokine CXCL8, diagnosis