CD8A and tuberculosis: By calculating the levels of CD39 expression as CD39pos and CD39neg, we observed that the percentages of CD39 + CD8 + T cells were significantly higher in MPE (15.97 ± 1.72%) compared to those in tuberculosis (3.74 ± 0.80%, P = 0.03) and exudative pleural effusion (4.47 ± 0.66%, P = 0.02) (Fig. 1B).