CD40 and CD95 induce programmed cell death in the human myeloma cell line XG2

We have previously demonstrated that CD40 stimulation induced a cellular growth arrest of the highly CD40-positive myeloma cell line XG2. To further characterize this inhibition of proliferation, we looked for a possible induction of apoptosis. Since no DNA fragmentation could be detected, we used newly described techniques that enable detection of apoptosis independently of DNA degradation, i.e. supravital exposure to propidium iodide (PI) and Annexin V labelling. We demonstrated that CD40 effectively induced programmed cell death. Furthermore, we have shown that CD95 (Fas) stimulation significantly enhanced the CD40-induced apoptosis.