CD274 and plasma cell myeloma: Cancer cells and infectious agents may evade early immune responses with other PD-1/PD-L1 mediated mechanisms: i) promotion of PD-L1 expression on dendritic cells and enhanced induction of Treg cells [29, 30], ii) overexpression of PD-1 on NK cells, as detected in patients with multiple myeloma [31] or infected with MTB [32] or HIV [33].