PDCD1 and neoplasm: Although represented at low frequency, higher CD103 expression was found within the PD1+CD28+ T-cell subset as compared with either PD1+CD28− T cells and the two PD1-negative subsets (Fig. 6D, left panel), differently from the scenario identified in the lung tissue, where PD1+CD28− T cells showed a gradual increase in CD103 expression, with highest levels at the tumor site (Fig. 6D, middle and right panels).