The phenotyping of pleural effusion CD8+ T-cells from lung cancer patients shows an elevated population of memory (CD45RA−CD45RO+CD27+CD28+) CD8+ T-cells and a low proportion of terminally differentiated (CD45RA+CD45RO−CD27−CD28−) CD8+ T-cells, which is similar to data from TILs. This evidence concerns the gene CD27 and lung cancer.