Abstract
Multiple myeloma (MM) is characterized by uncontrolled proliferation of malignant plasma cells in the bone marrow and peripheral blood. Here, we found that CD40 and CD40L co-expressed on XG1 MM cells and the coordinated expression of CD40-CD40L was critical for production and autocrine IL-6 in XG1 cells. Furthermore, TNF-α enhanced the expression of both CD40 and CD40L expression on XG1 cells. We also found that persistent CD40L/CD40 signaling was required for the constitutive activation of NF-κB in the cells.