CD8A and neoplasm: Moreover, while several ligand–receptor pairs were shared between CD8+ T cell–tumour cell and T cell–APC conjugates (including HLA-CD8), the latter clusters showed more co-modulatory interactions, such as between CD80/CD86 and CTLA-4/CD28 and between PD-L1/2 and PD-1 (Fig. 3f,g).