Dysregulation of CD47 and the ligands thrombospondin 1 and 2 in multiple myeloma.

CD47 and thrombospondin 1 and 2 (TSP1 and TSP2) expression were analysed by real-time reverse transcription polymerase chain reaction in fluorescence-activated cell sorted plasma cells (PCs) from patients at consecutive stages of multiple myeloma (MM) development. 80% of MM patients, but only 39% of patients with monoclonal gammopathy of undetermined significance (MGUS) expressed CD47; median expression level increased 10-fold with progression from MGUS to MM. Elevated TSP1/TSP2 levels occurred in bone marrow cultures from MM patients compared with healthy donors. CD47 and TSP1/TSP2 may have a potential role in the pathophysiology of MM, probably in the interaction between MM PCs and the microenvironment.