Abstract: Objective To detect the proportion of CD₄⁺ CD₂₅⁺ regulatory T cell and the level of sIL-2R and TGF-βl in malignant and tuberculous pleural effusion to investigate the local immune mechanism. MethodsThe level of sIL-2R and TGF-βl in malignant and tuberculous pleural effusion were detected by ELISA.Mononuclear cells were separated on a ficoll density gradient.labelled with antibodies,and then analyzed by flow cytometry. Results The percentage of CD₄⁺ CD₂₅⁺ regulatory T cells in malignant pleural effusion was significantly higher than that in tuberculous pleural effusion(21.1±2.3% vs 8.7±0.6%,P<0.05).The levels of sIL-2R in malignant and tuberculous pleural effusion were 563.2±92.61ng/L,390.12±101.12ng/L(P<0.05),respectively.There were not correlation between the level of sIL-2R and TGF-βl and the proportion of D₄⁺ CD₂₅⁺ regulatory T cells in tuberculous pleural effusion.The level of TGF-βl in malignant pleural effusion was higher than that in tubereulous pleural effusion(88.4±16.7mg/L vs 40.3±3.6mg/L,P<0.05). Conclusion D₄⁺ CD₂₅⁺ regulatory T cell,sIL-2R and TGF-βl could be used to distinguish malignant and tuberculous pleural effusion.

Key words: Pleural effusion, CD₄⁺ CD₂₅⁺ regulatory T cell, TGF-βl, sIL-2R