PDCD1 and plasma cell myeloma: Furthermore, our data highlight that TIGIT expression was specifically upregulated on activated CD8+ T cells in patient PBSCs, which coexpressed DNAM-1 and/or granzyme B. Notably, myeloma cells from patients, and the Vk*MYC myeloma cells used in our preclinical models, express the ligands for PD-1 and TIGIT, PD-L1, and CD155, respectively (1, 3, 27–29).