FAS ANTIGEN APO-1 (CD95) EXPRESSION ON MYELOMA CELLS/

Many factors involved in the proliferation of myelomas have been repor ted, and the relationship between these factors and the pathogenesis o f multiple myeloma has been discussed. We found that most myeloma cell s express Fas antigen/APO-1 (CD95), a cell surface antigen that mediat es apoptosis. However only some cells are sensitive to anti-Fas antibo dy and undergo apoptosis. These data indicate that some multiple myelo mas are generated not only by cell proliferation but also by cell immo rtalization The mechanism by which myelomas are immortalized is still unclear, but Bcl-2, Bcl-x(L), adult T cell leukemia derived factor (AD F), soluble Pas are all candidate factors for this mechanism. The poss ibility als, exists that inducers of apoptosis, e.g. tumor necrosis fa ctor(TNF), interleukin-1 beta-converting enzyme(ICE), Bcl-x(S), or Bar , do not have a lethal effect. In this review, we focus on the system that immortalizes myeloma cells, and suggest the possibility that mult iple myeloma constitutes one group of cells which cannot undergo apopt osis in the bone marrow.