Expression of the CD117 (c-kit) on myelomatous plasma cells

The surface expression of CD117 on bone marrow plasma cells from 86 multiple myeloma (MM), 5 plasma cell leukaemia (PCL), 1 MGUS patients and 10 healthy subjects has been analysed by flow cytometry using triple staining with the monoclonal antibodies CD138, CD117 and CD38. CD117 antigen was present in 26/86 MM, 2/5 PCL and 1/1 MGUS patients. Normal plasma cells did not show reactivity for the CD 117 antigen. Thus, in one third of MM patients CD117 antigen could be considered as a "tumour associated marker" and may be of value for the identification of the malignant clone in minimal residual disease. No differences were seen between occurrence of CD117 expression depending on stage of disease and monoclonal protein class.