PDCD1 and lung cancer: Consistent with the observations in patients, in vitro coculture with 4 different PD-L1+ lung cancer cell lines (A549, H460, H520 and XDC137, Additional file 2: Figure S3A), all resulted in a significant increase in PD-1+ DNT cells when compared with DNT cells cultured alone (Fig. 3e and Additional file 2: Figure S3B).