PDCD1 and neoplasm: This was further confirmed through immunohistochemistry of sections taken from the samples in Fig. 4D. Staining showed CD8 + and PD-1 + cells to be scattered throughout the tumour region (Fig. 5B); however, significantly decreased numbers of PD-1 + cells were seen in all treatments (Fig. 5C), although there was no significant change in the number of CD8 + cells.