CD4 and Miyoshi myopathy: Treg frequency is also positively correlated with PD-1 expression status in CD8+ and CD4+ effector T cells in the BM, with the same subset of CD4+ PD-1+ T cells co-expressing LAG-3/CTLA-4, indicating a more immune-suppressed microenvironment, with the up-regulation of multiple different immune checkpoints within MM patients that have PD-1 expressing effector T cells [24].