They secrete accessory growth factors/ligands such as IL-6, IGF-1, SDF-1α, B cell activation factor (BAFF), and a proliferation-inducing ligand (APRIL) and interact directly with MM cells, which mediate escape from immune surveillance leading to functional impairment of the host immune system as well as development of drug resistance. This evidence concerns the gene TNFSF13 and Miyoshi myopathy.