CD4 and Miyoshi myopathy: MM antibody production and resulting immunoglobulin levels produce significant defects in reduced BM B cell progenitor cells,[106] whereas general destruction of the T‐cell immune spectrum leads to an abnormal CD4+/CD8+ ratio.[107, 108] Meanwhile, MM highly expresses PD‐L1 (an immune checkpoint inhibitory ligand), which contributes to tumor cell immune escape.[109] In addition, BM stromal cells (MDSCs), intercell–cell exosome‐mediated secretion of cytokines, and impaired function and phenotypic changes in DCs play important roles in the pathogenesis of MM.