Thus, partial permutation test32 evinced that, in contrast to peripheral blood cells, CD8+ PD-1+ T cells from pleural effusion exhibited a distinct effector/memory population distribution (Fig. 1C, pies) with a predominant central memory phenotype (p = 0.05 comparing TCM between PD-1+ PBMC and PD-1+ PEMC, Fig. 1C, Bars), therefore suggesting an exhausted phenotype in the pleural compartment8,33. This evidence concerns the gene CD8A and Pleural effusion.