Expression of granzyme B and perforin in multiple myeloma

Multiple myeloma (MM) remains an incurable disease by conventional therapy. MM tumor cells evade the immune system and can induce immunosuppression by producing immunomodifying agents such as TGF-beta, FasL, vascular endothel ial growth factor and Muc-1. In the present study, we show that bone marrow cells from a patient suffering from MM IgG/k type, stage IIIA, when cultur ed, expressed granzyme B and perforin, normally expressed exclusively by cy totoxic T cells (CTLs) and natural killer (NK) cells. In addition, phenotyp ic analysis revealed that the cultured cells were activated antigen-present ing cells with NK targeting capacity. We propose that expression of these c ytolytic enzymes may constitute an additional adoptive mechanism by the tum or cells to actively destroy the host immune effector cells. Copyright (C) 2001 S. Karger AG, Basel.