NK cells isolated from pleural effusion show high expression of the immune checkpoint molecules T cell immunoglobulin and mucin-domain containing-3 (TIM-3) and lymphocyte activation gene-3 (LAG-3), whereas both molecules are expressed to the highest levels on NK cells and to a lesser extent on CD4 and CD8 T cells (22). This evidence concerns the gene HAVCR2 and Pleural effusion.