CD8A and neoplasm: In this instance, although a strong CD8 signal was detected (Supplementary Fig. 17), a negligible QD–RBD–tetramer signal was observed in the OVA expressing tumour (Fig. 4e left dashed purple line, Fig. 5d and Supplementary Fig. 17), confirming the specificity of QD–OVA–tetramer for labelling OVA-specific CTLs in the tumour induced by the pErNP–OVA–CpG vaccination.